california geology magazine april 1990

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DCAUIORNIA

"""'KlM<NTOFCQNS(RVATlON

DivisIon of Ml rr , ; .mel Geology

Understanding California's Geology

Our Resources - Our Hazards

llFORNIA

OlOGY

APRIL

1990

EarthquakePreparednessMonth

GEORGE OEUkMEJIAN.

STAlE OF c.u-OtNIA

GOROON ( . V VLECK. Sftn,'ory

THE RESOURCES AGENCY

RANDAll M. WARC. DQc;too

DEPAIlIMENI Of CONSUVAllQN



The Deparlment of Conservalion. DiviSlon of Mines and Geology joins withDES and other Slale, fedel'1ll, and local

groups 10 provide informalion 011 earlh

quake preparedness to California citittns.See page 90. Ihis issue, for proceduresand actions recommended by the SialeOmce of Emergency Services (DES) 10

plan. pr3Ctice:. and proteci yourself. yourfamily. your home and workplace fromIhe effecls of earthquake hazards.

April 1990 is California Earthquake

Preparedness Month. The devastatingmagnitude 7.1 eanhquake that occurred

011 October 17. 1989 in the Santa Cruz

Mountains made Californians acutely

aware of the need to be: prepared for anearthquake event. Approximately 80percent of the people in California livein seismic hazard zones where damaging

earthquakes may occur.

California Earthquake Preparedness :\!nnth

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BEAT THE QUAKE 74COASTAL LANDSLIDES CAUSED BY THE OCTOBER 17, 1989 EARTHQUAKE 75

ANNOUNCEMENTS 64REGISTRATION AND CERTIFICATION EXAMINATIONSMINING AND METALLURGICAL CONGRESS - 1990GSA/SSA MEETING

NAGT SPRING CONFERENCEGEOTECHNICAL EARTHOUAKE ENGINEERINGAND SOIL DYNAMICS CONFERENCE

CACTUS GOlD MINE . . • . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . .. . . 85

EARTHQUAKE PREPAREDNESS EDUCATION 89BEAT THE OUAKE 90BOOK REVIEWS 92MAIL ORDER FORM 95DMG RELEASE - OMG OFR 89-14, A BIBLIOGRAPHY OFVOLCANIC TREMORAND RELATED PHENOMENA.... . 96

CALIFORNIA GEOLOGY SUBSCRIPTION FORM.. . . . . . . . . 96

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"CALIFORNI .... ceOlOCY ....p"ll990



Coastal Landslides Caused By

The October 17, 1989 EarthquakeSanta Cruz County, California

8y

NATHANIEL PLANT and GARY 8. GRIGGSDepartmenl of Earth Sciences

Uni ... e ~ i t y of California, Sonto Cruz

...

N

LOC4T10N " '41'

"Salinas

Landing

'*-L!vermore

. . Monterey

Monterey Bay

Sanla

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The Oc:tobcr 11. 198geunhquakc(magnitude 7.1) ruptured a 24-milc

(40 km) long segment of the San Andreas

fault zooe in the Sanla Cruz Moumains,about 54 miles (90 k111) south of SanFrancisco (Figure I). The hypocenter w a at a depth of 11.5 miles (18 km), andpeak recorded horiwlIlal ground accclcr3

lions varied from 0.64 g11lvity (g) in Corralitos. 0.54 g in Capilola. and 0.47 g in

Santa Cruz (Shukal and others. 1989).This was Ihe largest earthquake in California since the 7.7 magnitude event on

the White Wolf fault ncar Bakersfield in1952. and the Jargc.sl evcnl on the San

Andreas fault since: Ihe: 1906 earlhquakc(McNally and others. 1989). Theearthquake caused damage and local

emergencies in Alameda. Conlra Costa.

Marin. Monlerey, San Benito. San Francisco. San Mateo. Sama Clal"'oI, SantaCruz, and Solano counlies. At least $6billion in damage resulted from the earth

quake: 62 people died and 3.757 wereinjured (Plafker and Galloway. 1989).

INTRODUCTION

EJ:tensivc ground frolcturing and crack·

ing in the Santa Cruz Mountains resultedfrom a combination of the severe shaking

and the reactivation of a number of verylarge "anciem" landslide masses. lique-faction led to subsidence and formalion ofsand volcanoes (also called sand boils)along the San Lorenzo, Salinas, and Pa

jaTO rivers a . ....-ell as in the Moss Landingarea. Widespread failure of the sea cliffs

also took place between San Fr:mciscoand Monterey.

HISTORY OF SEA CLIFF EROSION

Landsliding in marine teTmc,;: terroiinhas been rccogni7.cd as a geologic hazardalong much of the California coastline(Cleveland, 1975). The Sleep. oftenunvegetated sea cliffs bordering northernMonlerey Bay clearly reflecllhe effects ofactive erosional processes. Erosion rates

here. due 10 both marine :md nonmarineP'"ocesses. vary from severoil inches toseveral feel per year and arc controlled

pnmarily by lilhology. structure. ~ l r a t i g raphy. and eJ:posuTC to wa\'c energy

(Griggs and Johnson. 1979: Griggs andSavoy, 1985). These p r o c e s ~ s includebolh hydraulic imlKlct and scour fromwinter Slorms. as well as ma ..s movementsassociated with imense rainfall. and, Icssfrequently. IIm..5 mo\,cments associated

wilh e a r l h q u a k e ~ . Although construction

...figo.or. 1. Son fronci1CO Boy oreo. $howin.g the

epicenrer of the October 17. 1989Lomo p".toeorthquoke in rhe Sonto Cruz Mounroin$, of,-<.

.hock zone. mo,n trOCI of rhe Son AndreO$ Foull,

ond other nearby foults..

CALIFORNI4 GEOLOGY Ap,i11'l'9O

"



I • =\,

.. . F,gllre 2. Pion view and

longil\ldinal1ecllon

,howlng the locolion and

d,menslons 01 sea e1,H

faIlures os well a, the ge

ology between Seabright

B e o ~ h and N _ e"9htonState &eoch.

. . . . -. I . . . . .Sol•• _

of coo),lal proccclioo l>lruclurcsh a . ~

~ I o w c d cm.ion of the coastline by marinep r O C C 1 > ~ in some a r c a . ~ , mass failureconlinuc." 10 take place along both pro

tected and unprorcclcd bluffs. Thus. sci

c n l i . ~ I S . planners. and developers find thaIrecent events continue 10 push the l imits

of c o a ~ l a l crO!>iOll landward.

lIyt1rJ.ulic impact and scour arc respon

sible for cTO!>ion al lhe base of the sea

diffs wherever cO:I...I..1protection 1>1 rue

lures or wide protective beaches ar c

absent. Typically, the cliffs arc undercutover lime Wilh subsequent failure of lhe

overlying material. As this material falls

into the surf ~ . o n c . it is broken down bycontinued wave aclion lind carried away

(Griggs and Johnson. 1979).

Sea cliffs over-steepened by WdVC

induced erosion al their base arc also

SUM:cpliblc 10 mass failure during hc:lVy

minfatl as a resul t of eleV3led groundwa

ler condilions. Such failures ar e common

in bedrock along joints* or othcr wcak

plano. and within lhc overlying. less

consolid<ltcd marine lerracc deposilS. al

luvium. or ...oils. Sea cliffs protcctcd from

marinc crosional processes commonly de

velop a lalus ...Iope at their base whereas

the upper portions remain steep. Ilcavyf"Jinfall may induce failure in both lhe

talu......lopes and :llong the Cltposcd up!'Cr

portion of the dirr. Foreltample. inlen."C

r:lin...lOrms in Janu:lry 1982 cau."Cd wide

~ p r c a d failure along lhe cliffs of nonheroMonlerey Bay between New Brighlon

Stale Beach and Rio Del Mar. These

...lOnns cndllngered cliff top s l r u e t u r e ~:lIld danmged or de ...troycd beach h ( l u . ' > C ~( G r i g g . ~ . 1982).

Large e:lrthquakcs. such a, lhc October17, 19119 evenl, arc liiso c:I[);lblc uf pro

ducing ~ c dirf failurc. !'ilrex:ullplc. In

lhe Ocluber II. 1865 ( : l p p r o ~ ' I 1 l : l t c 6 5

m:lgnilude) Sanl:l C r u ~ Mount:lms carlll

quake, lhe .'itllllfl C"'= SI'",i",,1 I 1l:\6S)reported that ovcrh:lnging cliff, rctlmlO

grnded H J a d ~ . "below Soquclthe highd i f f ~ crumbled into the "C:I," and "a l'onlinuou... cloud of du ...t rO.'oC along the cliff...

hctwecn CaSlro's Larnlmg (no....•called

Rio Del Mar):loo Sanla Crul." Durm!'

lhe gre:lt 1906. 8.3 nl:lgnitude carthquakc"much c;jrth fcll from bluffs ne:lr lhe

town" (Capilola)(Uwson. 19(8). It I'"

3warenttllat I:lrge earthquakes can cause

inst:ulIaneous clifT relrc:lt :md also

WC<lkcn .;e:l cliffs through seismic shak

mg. forming cracks :lnd ris ...ures, thcre!)y

1000re:J.'ing lhe suS(;eplibility of the cliffs

to sub.'>Cqucnt fail urc.

EFFECTS OF THE OCTOBER 17. 1989EARTHQUAKE ON COASTAL BLUFFS

Three key ~ t m n g - r n O l i o n ...tmion ... tI!'Cr

aled by lhe Division of Mine ... :lnd Geol

ogy provided lhe f i r ~ l quantilalive r e c o r d ~for an e:lrlhquake which affcctcd cO:l ...lal

b J u f f ~ (Slwkal :111(1 olhc...... 1989). Prior to

October 1989, enginecring geologiMs

who...ludicd C(>a...tlll bluffMability wer\'

limitcd ttl dc.'>Criptivc interpretlilions of

...lrong molioll in the ncar-ricld. or h:ld 10

eltlr.lpol:lle in'lrument:ll dala ten, of

miles from:m cpicenler to lhe chff sIte.

By fortuilou... circum'lluICc.... the cpi

CClllcr, thc c t l a ~ t : l l c1irf.... :lnd lhe ~ I r n n gmotion inSlrUmenl ... were all cIO\C 10 exh

other for the Loma l>riela carthquale.

Thi"'l'rovides a new:loo unique dlll:l M't

which will he helpfUl for quanl Itam'e

: I n : l l ~ i s of eoa-'ital bluff... c1"Cwhcre.

Thc.'>C new strong-motion dala forcoo ...t:ll Santa Cruz CounlY ar c ...urnma

r i ~ c d on Table l. It b signific: ll ll for

coastal bluff ~ t a b i l i t y thai ""rI;mf gnH.lI1d

mOllon of :lbout 0.40g 10 O.60g occurred

along the coaStline in the ncar-field. It is

infcrred thalllQrbmwl ground motion

was 1m the order of0.47g 10 O.64g for

nC:lr-ficld c o a . ~ t a l cliff.... Th e illlen ... ity of

,haling W:IS VllI on lhe Modified Mer

c:llIl scale. Th e durntion of ~ t r o n g mOl ion.... hieh :lrrcclcd cliff silibility was on lhe

ordcrof 10 1015 second....

On Novcmber l. 191:19. :I leam of gcolo

g i ~ I S videot:lped and phol<>gmllhed the

coastline belween Oolinas and Monterey.

C:llirornia from :m airplane and nOled

many land... lide ...ca r.... p:lrlicularly be-

twecn Capilol:l and MO.'>s Landing (Figure

I). The videotupc facilit:l tcd subM.-quentmapping of individual ...!ides onto a ttlJlO-

gmphic ba.'>C map (I inch = 100 fcCl).

TABLE 1. NEAR.FIElD STRONG MOTtON

lorna Prieto Eor1hquok. of Qclober 17, 1989

location of Epic.ntrol

Station Distance AcclerQllon

Co<rol;t01 SMIP 4.4 mi 90" O.S09

U, 0. 479

360" 0. 649Copitolo SMIP S.6mi 90- 0.479

U, 0.60g

360- 0.54g

SonIa Cruz SMIP 9.9mi 90- 0.44g

U, 0.40g

360· 0. 479

Dolo from Shokoland others. (1989).

76 CALIfORNIA GtOLOGY Ap"lt9<xl



More detailed !round observalions com

pan:d lithologies. ltlruclllntl and slroligraJlhk weaknesses. and potenllal foradditional failure (such as bluff lOp crack!.landward of the failure area). A review of

hisloric aerial slereo photogmphs and re

lated Iiterniure. used 10 compare the Oc

tober 17. 1989 even! 10 bolh prior hlsloricearlhquakes and recent large storms, indicated thatthe:.c observations Iypify Ihe

effttlS uf large earthquakes 011 sea cliffs;ll\d that Ihese effects are compantble to

lhose resulting from heavy rninfall.

Coaslal bluff failurel> resull ing from

the Oclober 17, 1989 earthquake occurred

bo:tween San Francisco and Monlerey ina \,:mety of lithologies and slope condi

tions. In norlhern Monterey Bay. oclw,,:cnSe:tbright Beach 10 Ihe norlh and Sunsel

Stale Beach 10 the ,Mluth. there arc excel

lent c'\:tmples of lhe lithologic and morphologic control over earthquake.inducedsc:t cliff failure. Three main differencesin lilhology along lhe coastline of north

ern Monterey Bay result in three dl.slinet

types of earlhqu:tke induced failures.

Photo 1. Jai,,1 conlrolled wedge foiture i" tho P1ionne PU"limo Formot'on.Mor''' ' e.o,io" procoss.,

undercut the!O cliff•• which lOlled olong Inler.o<:l,n9 jo,,,t plo"e..

Scbmic shaking inilialed numerous

rock faits and blod. falb :tlong this \Ce·tion of coast. Undercut :tnd weakenedbedrock and frneturcd promontories col

lapsed along with btufflOp lermce depus

lb. Failure alongjointl>urfaces allowedlarge blocls 10 l>Cpardtc from more Inl:tCI

rock. The si/.t ofthesc failures w a dependenl on Jomt spacmg and ortentation.

It is eXlcnsively JOinted ;lIId l>ul>Ceplible to

wedge failure along joint \urfaces (l'holOI) . The unconl>Olidaled lermce deposlt\

typically COlll>ist of marine cobble\ overlain by l>hallow marine to eolian l>ands.

aoo a fluvial conglom(Tdte that is cappedby a thin soil horizon. The nearly \erlical

SC;I cliffs in this arca are :tcllvcly crodmgwhere they are not pr01ceted by revel

mellls. SCllwalls. or a wide l>andy beach.

In generdl. where unprotecled. lheeoarse.grnined ;Ind ",,'CII-jointed Purisima

Formation erodcl> at a relatively rapid rate(about 12 to 24 inches per year: 30-60 emlyr) (Grii!gs and John'\On. 1(79).

Between Seabright Heaeh and NewBrighlon St:lle Beach (Figure 2). scacliffs are cui into a marine terrnee that is

up to 75 feel (25 m) high. This lerrace

consists of an uplifted w:tvc<ut bedrock

platform Ihat is overlain by several feCI of

terrace deposits (Figure 3). The wa\'C cutplatform il> in a Ihiekly bedded to massive

siltstone wilh prominent she1l1ags* (Pliocene Purisima Formation). Even lhough

the Purisima Formation IS well indurated.

- - '/

.. . Figur.3 810ck diogrom UlOw,

ing 'eo cMI"N"'ure ond IypIColfoitu.e .lyle ,n '0 0 cliffs unde.·

10,,, by well·to,nled P1iocone

Pu.is,mo fQlmohon .a"tono.

Nole tho 10....0 " crock. in the

P1ei.tocene Ie.roco dopo"" ondu..dereul .eo cliff

cliff heigh!. and t(l('* support. High eliffl>

"ith w i d c t ~ \paced. l>ub-\'enieal Joinhand in:ldequ:tte toe \upportl>uq:tined the

largc\t m l > t " l l l a n e o u ~ and incipient failures in Iloeakened or undercut sedimentary

rock. Toe support in the form of a shore

platform. revetment. !>Cawal!. or widebeach i!enerdlly inhibited failure. AI·though the densily of failures diminished

away fronllhe cpicl.'ntral region. sc\'cral

large slides and rockfalls occurred as farnorth as D:tly City (photo 2).

Dall1:tge to private property ;lnd public

struclurel> was minlm;ll ;llong the cllffl> of

th b area with the cxception of the diffs

1Il111ledi;ltc1)' eal>t of Capitola. In this areabedrock :tnd lerraee dcposits loppled to

the beach below:too extenl>ive bluff lOp

fmt'lurmg abo occurred. This eauscd fur

ther damage to walb and foundationl> of

an ;lpartmcnt eomple\( (already o\'erhang

mg the \ca diff. PhotO 3) and additional

failure to an :tbandoned diff top publicrood in the Capitola area.

I'rom New Brighton State Beach 10

Aptos Creel (Figurc 4) , an interbedded.pebbly. eross-bo:dded. moderdtely indurated. and weall) Jointed s a n d ~ l o n e member replaces theJOinted sihl>lOne memberin the Purisima Formallon and underlies

9O-114-foot (30-38 m) high cliffs. TerrJee

deposits. conMsting of poorly conMJli·daled s:tnds and inlerbedded pebbles.poorly sorted fluvial conglomerate. and athin ~ o i l horizon. lire aboul 15 feet (5 rn)

CAlifOIlNIA GEOLOGY Apfllt990 n



Photo 2. Lorge coo.tolland.lide near Daly City. Nore th.e pro.umlty of cliff

top hou1."" 10 Ihe head scarp.

Pharo ... hrenl<ye leo cl,ff failure ab e. .. . La. 0101 Doye. Failure occurred in the upper 36 f_ (12 m)

of Ihe c ~ f f and loose molenal cascaded down Ihe .I""p slope. Note the many hous"" both obeye and

below rloe land.llde thor are leopard,zed by >lope faIlure.

F'tlolo 3. 81uHs eOSl 01 Capirolo. Collapoe of lerroce depo.il1 and ..mderlY"'9.

exlenSlyely JOInted ,il"Ione further uncHIrmlftfld the preYlau.ly eKpa.ed

foundallan of Ihil aparlmenl building

Seismic \haking initialcd t.....o types of

failurc here. Trnnslation· (uniform movement) along a joint or wcathcring \urfllce

produced many large slides up 101110 feel

wide (60 m .... ide) Ihal originated in Ihc

upper 36 fcct (12 01) of Ihc sca cliff(photo 4). Thc scarps of Ihc'iC slides lcnd

to cut vcrticall) through thc Quatcrnary

tcrr.ICc d e p o s i t ~ and thcn nauen as thcyapproach Ihc Purisim:l FOrm:lllOn (Figure

5). Decp t e n ~ i o n cnlcks cut through thcterrace u e p o s i t ~ (Photo 5) :IOU w lh 3-18feCI (1-6 m) lanuward of maoy of the

scarps: ucpth of cracks Icnds to increa!>C

wilh Ihe si/.c of the scarp (Figure 6).Some intacl blocks and much l00:.c o;()ll

cascaded down lhe face of the cliff. formlOt; 60 foot (20 m) high coalescing talus

cones lhat partially buried somc autornoblles and blockcd access to homcs(Photo 6).

Ihid: and thin to the cast. Seawalls :lnd

rc\·clmcnts. which protcctlhc beach fronldcvelopment. isolatc the base of Ihe eliff

from marinc crosion: the upper portionsofthc cliffs continuc to fail periodically.

78 CALIFORNI .... GfOLOGY ....p"ll'1'90



"""Crec:t I

Tp

In the lo\\.cr 30 fecI (10 ml of the cliff.

the sandstone was undercut by fr.telUring

along intersecting conjugate joint scts.Blocks 3 feel (I m) thick and scvcr.l1 (eel

high broke up easily and formed smalllalus cones. Though fraclured and par

tially detached from the cliff. many

blocks did not fall and !'Cmaln as unstable

areas.

Three t y p e ~ of earthquake-illdueed fail

ures prevailed along this streich of coast.The firsllype was a shallow dry SlIndflow t e ~ s than 3 feel (I m) deep. 15·30

feet (5-10 m) wide. and 30·60 feel 110-20

m) long. which origlllalcd well below the

bluff top (Figurc 8. Pholo 8). A vertical

scarp eUlthroogh a thin. cohesive soil

la)er 10 a failure surfaec lhat paralleled

lhe bluff face. LOOM: ~ a n d or small blocks

of more eoheSI\"C malerial. often held to

gelher by rOOlS. slid along lhis surface

arlCllhen ramped over the less Sleep lalus

d c p o s i l ~ allhe base of the slope.

f,gure 4. Plan view and long,tvd'nolse<;lion

showing lhe location onod dimenllons of sea cliff

failures as well os the geology be_n New

Srighton Sklte Beach ond Apto. Creek. A 5Onod·

.to". member rlplous the siltstone rnember of

the Pliocene Pumimo Formation fTp)inthi.oreo.

<l1li Figure 5. Siock diagram ,how.

ing structure and !ypt<:olioilurl

.tyle ,n .e o c1,ff. unodenain by5Ondstone rnember of th .. Pli.

ocen" Pu,",,,na F o r m o ~ o n . NOI"thot th" f<Silure occurr..d ,n th"

uPfl'Or portion of the cliff ondmot"riol cascaded down the

sleep slope

Photo 5. Deep tension crock in terrace depows. These crocks oflen cut through house foundations

and ,ndicote the polenllOl extent of future fo,lure

damage (PhOIO 7). The loose surficial

sand liquificd and flo\loed downslope over

a wealhered. I c ~ s permeable surface andinto h o m ~ :lIthe base of lhe sea cliff

(Griggs. 1982).

~ 0Q

,,

"'., '..',

""'.,.......

~ ' ' ' ' . ' ' , " . "

Between Aptos Creek lind Rio del Mar.

semi-eonsolidalcd coli:1n and fluvial

sands (lfthe Plcbtoccnc Aromas Formation form 75-120 fOOl (25-40 Ill) high,

~ I C C P cliffs (Figure 1). The upper 6-15fect (2-5 rn) arc more cohesive than the

underl)ing p;lrtly consolid:llCd and

weakly cemented sands. Sea walb andre\'Clm<:ntS thaI prOll:cIlhc back-beach

de\clopmcnl abo protccllhc cliff toefrom W:I\'C lIlducc<l erosion. However. lhe

bluffs continue to fail periodically. asthey did in the IOQ-year Slorm in January

1982 lhat caused e o n ~ l d e r J b l e properly

"---,.O U . ' U H ' ~ '

'Ul•..,. . . . . . . . .

CAliFORNIAOfOlOGY "p"ll990

"



Photo 6. Vi_ facing east along lo . Olos Drive. ..Moteriallrom a foil,,'e in rhe "pper port of the

bluff cascaded down lhe slope and blocked

til. ,ood. Nole the relephone pole b'okenbytil. Iondolode

The !>Ccond I)pe of earthquale failure.

larger I r a n ~ l : l l i o n a l slides. scveml feCideep and up to 90 fecI wide_ occurred inthe upper 30-45 fcct (10-15 111) oflhe diff

face where ncar-\'Crtical cliff tops e,\;isled

before the earthquake. These f3ilureswere similar to the failures in Ihe sand

slone member of lhe Purisima Formalion(Figure 5). A 3-9 fOOl (1-3 m) \erlkal

scarp cullhrough Ihc morc eohcsi\c soils

Ihal were underCUI by dov. nslope failureof underlying. less cohesivc soils. LargeinlaCl blocks, }·6 feet (1-2 Ill) lhick. and

loose sand from lhe upper portion of Ihe

cliff cascaded down the slope and lensioncracks up 10 30 fecI (10 01) rormed 13nd-

ll.':Ird of the ~ c a r p ~ .

o 100 ft.

• •' ' : ' ~

.. : ....

.

ll'.GENO__ lension crath

A'1":JCs caTp~ l h i l u r e surface

" ' I ' i . ~ d c b r i s palh

U-- la lus

iI

staleCOnlour interval = 5 feel

Fig"re 6. Deloil. of 'eo d,H fo.I,,'es and len"on crack. Not. the prevolenceof rens.on crocks near the lorge la,I",e.

Photo 7 Slope foilure In 1982t1lot de,troyed a house on ~ Drove. Thi.rype of ~ diH fail",e i. very "m.la. ro rhat cOU$ed by the October 17, 1989eorthquoke

CALIFORNIA GEOLOGY Ap"ll ,90



""'00..

60 q OA '. :40 :. : . "

:", '.",;'-''''-----'''-'lll-l'---'-Jell-__-"'LJCCLL1-'L-l'---U.-'''--'''-__--''-__-l!o.l.L!L-.J1lJ-ll_--'' -----'

..

The lhmll)pc of c:trlhquakc f•• ilurc i:-

a Iran,I:oliul1al ~ l i u c . South of M ; l I 1 r c ~ ~ 1Slale B.::ach (Figure 9). ".nds c O l l 1 p o ~ i n gthe dirf, arc Ie" consolid,l[cd and the

elirf, arc therefore Ie" l>lllbic. Thi,

mc[ch of elm, b fronted b)' a wille prnlcctlve "each. During the canhquakc. "w.:ry large [mn,laltonal slide. 300 feet

(rOO m) wide and 6-9 feel (1-3 01) deer.undermined 15·)0 fecI (S·IO m) of lhe

dirf'tJp above lh c PI:tcc de \ 1c r dcwlop

menl (hgurc II. l>holo H), Large mt,lt ' l

block, toppled frollllhc upper 15 feci (S

QI) ,If ,jope while inlact p,lh:hcl> of \nil

held IOgclhcr by rOOIS. and 100M- loOlIlU slid

down the slope 10: . ru."I"',l)'. One hllu'c

and iI ' retaining wall S)'\IClll were Ur1ckr

CUI by the slope "ollap!>C in this area: llle

hou\c had to he d l ' m o l i ~ h e u .

FlInhcr 10 Ihe 'OOlh. Ihe waslal b l u f f ~mlhe SUl1scl Slale Beach arta (Figurc 9)

c o n ~ i ' l of weaUy e o n ~ o l i u a l e d PICI'lol'Cne dunes (WI'iConsin age; Dupre. 1975)which havc hccn \Iahili7cd by \ ' < ' ~ W l : l l i < m .HOlllcl> ha\'e lx.'Cn buill 00 lhe eroding

edge of lhis :!ncienl dunc complex. Slope

failure III Ihl' :Irea IXcurred "hen ,h:ll

10"- 'I:tb, ull lt l. l fCCllhtd., "cre dCI:let>ed

and lr:uhlalcll ,horl Ji'1l!nce\ UOWlhl\lf!C

II'hOlo 9). Til l ' form of hluff relreat h:!,

threalened -e\cr,tl horn.:, :Hld alka'l O'IC

will bcr;;:ll)('.':lted.

figure 7. Plan view and long'ludnal'IlCI,,,n

show,ng the locol,on "nd dimen""", 01 leo cliH

foilurel and lhe geology between Aplol Creek

ond R,o Del Mar.

1...· · '- _

Thc lilhology of Ihe M:3 clifT maleri:lls

c()fIlrottcd lhe mode of failure al mOSI

loealionl>.P r o m o n t o r i e ~ .

headlands. andnarrow peninsulas Of ridges along lhe

l·OO.,1 were c o n s i ~ l c l l l l y the siles of lhe

m O ~ 1 extensivc failure (Pholo 10). On alarger -.c:lle. SC1<:miSIS also noted Ihi\

e((crl in lhc 5ama Cruz MOUnlainl>. as

a !"el>ul1 of lhis earthquakc (pla",er and

Galloway. 191:19). and in Olher areas

where large earthquakcs havc occurred in

lhe p a ~ 1 (ilarpallu olll<:n.. 1981). In lhese

non-coal>tal : l r C 3 _ ~ , lhe ground surfaceIopo£r:lphy e:lused refleclion of s.::ismic

Photo 8. Very lorge dry >and flaw above Place de Mer d.....elopmenl. HaUl. . at the top and bolt of this

10,lure _ r e 01 r;11t.

"-

". "

.'-:..-0;:"'- - - ,.."'.....

. -. .

Figure 8. alock diagrom 01 dry IOn<! flow in weakl, conlOlidaled dunel.

Notelhe lenlion crocks in lhe coOO;"e I","oce 10,.•.

CIIllrORl'llll. GEOLOGY Apo,II990 81



SunK' S l) 'e Dc..:"Manrcua S li le Sneh

Q. * 00"",,,, A,,,,,,,, F., ...,...

Qo 0-"""'" ._4,L I _ ~ l c · ' _ - , y · = ' __ql:''---='Lj4__ '':J' ~ h k : o,...'00.,"'.,20

o' - - ' ' - - - - - ' L L L - - - - ' ' - - " - - - ' - - - - - ' ' - 1 U . ' ' - - - - " ~ - - - - - = - " - - ...., - - J ~ - - - - ' - - - - - . . . J",:1\0; cOIl-trul'Ii\c Interferem:.:-· Ihl.'ll

amplified the iocoming i>Cismic energy,

m c r . ; ~ ' I . ' C d Ihe <I) natuic ~ t r c ~ i > C S . alldcUll,cd rock or ~ o i l failure. 1I0\\le\'er. the,i t.... of the ground \urfacc structure th"1

can refiecI incoming ~ c i s r n i c wa\"cs m U ~ 1be on the '3mc order a the seismic wave

length (Harp and mhen- . 1981). Thus.

variations of lhe topography with dimen

\Ions of lens of miles will inlcrolct with

long seismic waves. On the OIhcr hand

\ca di f f... ""hi{'h arc lens of feel high will

nOl respond to long w:l\'c1cnglh.... Ther,'

fore. the fcpc;llcd failure along lhe

coast:ll promonlOrics and narrow ridllc\ i,

proffilbl) due 10 lhe bek of tiltcral support

durmg lhe imen"C shakin1: r..llher lhan to

t o p o ~ r . l p h i c amplification.

place III lhe pa.!>l :md aid In rel:uing lhe'C

failures 10 enher ltChnnc or ramfall Cllcnh.

For cX;l!l1ple. lhe aenal p h o t o ~ n l p h , oflhe norlhern MOlllerey Hay eoa,tltne e ~ lend back 10 1928 a n d , ~ the changes

1),·er;1 pcriod uf 60 )·ears. These phOlo

graphs e1eilrly s periodic shallow

failure or sloughing of lhe bluf" and

wide,pread bluff failures lhal occur after

heavy precipitation. MO!>I often. lhe fall·

ure, He miliated III lhe blufftop terrace

deposit, and may eXlend atllhe way 10

lhe baM: of the bluff. Where lhe lhiekness

nf lhe failed m:lterial l great enough. lhe

1>tt.o.ep slope, produce f J o w ~ lhat dallmge

ilnd deslroy the h o m c ~ below. The inci·

figure 9. Plan ",ew and longitudinal secl,on

show'ng me locallon and d,menlion. 0 1 _ cliff

foil"" . . and geology b<!tween R,o Del Mar and

SunSe! Slate Beach.

d e l l 1 ~ of bluff failure ofthi, I) pc are

retallvcly common. occurrmg every

lO-t5 years on Ihc3VerJge.

If [ar1:t.' scale. de"p-,e,lted bluff failure

o,:curred dunng lhe t906 ear thquake. or

in the t\\'o llmgnilUde 6.0 e ' · e n t ~ lh31 occurred on the o f f ~ h o r e San Gregorio f;lUlt

m 1926, it might be expecled lhat .'>Ome

e\idcnce WQuld be prc.\Cnt in the 1929

:Icri;ll pholognlphs. The p o o w ~ . hO\levcr.

IMPACT ON FUTURE LAND USE

DECISIONS

Seismically indu(·cd coastal bluff fail

ure w a common up to 47 miles (75 km)

from the epicenter of the 7.1 magnitude

Oclober 17 carlhquilkc. The e1iff failure

1ll del/eloped arCilS of the coa.\l prn.cd

rhl.., to ~ l r U ' · l u r e ~ on the bluff lOp a \lell a, the pril/ate and public structure,

on lhe beach below. One death oc,·urred

on a beach IlOrth of Santa Crul when

~ l '>Cction of weak bedrock in a cliff

coJlajhCd onto a sunbathcr.

The lWO geologic hazanh eonsi'lenl I)

identified ill CO:ISlill ~ I t e : . in c o n ~ u l t i n ~ ~ port.!> arc l t C i ~ m i c a l l y induced slope failu and slope failure induced by excesswaler. Soil properties and ,tope configu

mtion arc commonly used in sile- 'peeifie

,lope ,tilbility analy,b. S\IIdy Orhl'lOri·

cal ~ t e r e o aerial p h O l ~ r a p h ~ can indi'"ale

"here and \lhcn slope failure has tilken

Pholo 9. large dry KInd flows ooo,..e Sun.et Stole Beoch, One of lh . bluff lap hOllles will b<! moved

foo1her bock Irom the edge 01 the c1,ff

" o . L 1 f O ~ N I ' " GEOLOGY "'p,,1 19'10



Photo 10. hlens,ve slope failur. and ctocking on a narrow ridgil Th,s house w.11 be tom down or>d the

slope will be groded to 0 sofer angle. H.,.,... . below 'h'l foilur. wete evocuoted

Glossary

co • • ,. . . . . . . . . . . . . . . EI ..... two___ r t l O d t o ~ _

.........ioiIlt - 0 --. 01 ftadur. ow portillo '"'.-. . . losinahel. . - .... ~

. . . . . . . 01 lISUOI, hon:I rod

h..yh ...... "-- '11 Oft a aurfoce

oftar fin., IIICIIarioI t- bNn blown

by wind ow wo.n.d OWO)' by_.. . . - ....__ -vin ol

IlkJurbed ......... 01 0 IoftdaW" ow

IDw. - - t ' " 01a _ cYf

• ' ,0 ••1.... '-abldllide: I _ C ~ ~ d o = ' hp.lI.pl • • 00toiJ.fod .........

Oft 0 poraIel to ....--- .....

show a bluIT configuration .... Uhoul e\i-dence of any major or deep seated failure.

There are extensive areas along Ihe upper

bluff\ in lhe Rio Del Mar area lhal appear

dCVULd of \'egetalion in lhe 1928 phOlo:..

suggesting n:ccnt failure. [n general. the

aerial phot:o record Indicates that the lype

of coastal bluff failure expected In lhis

area during a map earthquake is similar

to that c'!.pected dunng intcnsc rainfall

C\"Cllh. namely <,hallO\\ surficial failures.up to sc\Cral fCCllhld: al most. The (kto-

ber 17. 1989 earthquake provided an op

portunily to check these interpret:nions

and hazard assessments.

The area" "here lhe e.xtensl\"e damage

occurred during the October 1989 earth-

quale. and \I here homes rcccncd the

Illlr.>t dama!!c..... cre those that failed most

frequently dunng past epl"'Odc<, of lnlen\C

ralllf:111 a\ ~ h O \ \ n II I aerial pholographs.

1\long northern Monlerey Bay. the a r e a ~of mOSl frequent f:lilure arc the ~ l c e pbluff\ CU I into the Pliocene l>unsim3 For

mallon from the L3 .. Olas Drl\"elSeachITStOlte Beach area to Aptos Creel. 3nd IncbluIT\ composed of the .....eaUy eon'Oli

daled PleIstocene Arumas Fonu:nion.

\I hleh e'!.tend from AptosCreel doY. n

coast 10 La S e I \ ~ J Beach.

The lOp. slope. and ba.>e of coa\lal

bluff, an:: potentially endangered by

eartt!qu3ke-induccd \Iope failure. lIecc!>

Sltatm!: costly mll1gatlon r n e a ~ u r e , . At

the top of bluffs. sc\"CrJI <,trueturcs \lerc

immedialely damaged \lhell c1iITf3ilurelIndermllled the foundallons (PhOlO 3). In

nearly all e a ~ e s of f:lilure. tension cracks

up 10 JO feel (10111) formed behind the

head of ! > C a r p ~ . and in .;ome cases cuI

through h o u ~ f o u n d a t i o n ~ (Phot<K 5 and10). Crncking 3nd slope failure "ere <;()

eXlenSI\1:: at thn."'e bluIT top sites that the

homes had to be d e m o h ~ h e d . Two ofIhcse hOnles were bUIlt 011 vcry narrOl"peninsulas (Pholo 10); the third w a at

the c r e ~ t of a \ 'cry high. steep. narrow

seclion of bluff lOp (PhOIO !I). T h e ~ e blufftop c r a e l ~ probably represenl incipienlslidc.-. thaI may fail under winter con(h

tions of increased plI1'l: pre!>SUre. The

depth and \I ldth of such cmcks can be

u.scd as a reas.onablc mdicator of polenllalbluff top failure dunng \Ci,mic sh:dlllg.

Most of Ihe sea c h f f ~ Included II I thl\

~ t l l d y were 100 ' leer lU support ~ I o p c conSlruclion. and lhc h:Il.ard of building on

such tocallons IS verified by OO\Crvations.

In S C \ · c r a l l o c a t i o n ~ . nlld-slopc s l t e ~ rec e i ~ ' e d debris from upslope failuro:!>

(Photo 8) ,

l 1 a : u r d ~ 10 h o u ~ al beach !c\'c1 re

!>ulted from failure of lhe cliffs behmd

lhem. Such failures led to the damage

and e'laCUallon of a number of h o u ~ ~ inlhe Las O l a ~ Drive and Beach Drh'eareas. The h o u \ C ~ bUill c1o"\l::Slto Ihe ba'C

of the bluff!> wcre mo:.t !>u'Ceplible to t h l ~t}peofdamage.

MItigation and risl reducllon measures

began wilhm one week of the earthqu;U,.c

and included fellC"ing oIT d3ngerous Sites.

culting back o\whangs. and removing

lrees from the top and stope of the sea

cliff . At Silcs where bluff lOp houses had

10 be demolished due to lhe lhreallhey

IJOSCd 10 hou"Cs at beach le\1::1. eXlensive

grading was n.-qulred to rcmo\'c and

stabilize the cr.acked bluff top areas.

CONCLUSIONS

The October 11. 1989 earthquakepro\'ided an opportunity 10 obsene lhe

e f f e c t ~ of a large earthquake on ~ I o p e "IabilllY. Sea cliff f:lilures :llong the e:tto:n

~ i \ " C l y dc\"Clopcd oorthern MOnIeri:'} Ba}

coastline demonstrated bolh lhe hazard

II1duced by carthquales and the gcneral

l I l ~ t a b l l i t } of coastal bluITs. FaIlures pr0-duced b} the recent earthquake Otturred

In bluffs lhal were acth'CIy erodll1g (Photo

3) :lnd in bluff, thaI were protected from

marinc ero:.ion (PhOlO 4 j. Furthermore.

narrow r i d g c ~ ur p r o 1 1 l o n t o r i e ~ were 00·!>Crved 10 be 1lllJ!lllilely 10 ! > u ~ t a i n SC\'erc

damage (PholO 10). Allhough the earthquake caused masshe inSlantaneous fail·

ure. r ~ i d u a l . .....ealencd bcdrocl and soils

ma} expenence IIlcreased erosIon and

failure rales as the typical cyt'1e of winler

\tonns ballet'> the coastline. Current and

fUlure dc\l:Ioprnenl proposals along the

c o a ~ l !>hould consider lhe evidence and

experience gaillcd from l h i ~ earlhquake10 evaluale bolh building c o n ~ l r n i m s andlhe feasibilily of hazard mitigation

measures.

CALIfORNIA GEOlOGY A""lt990 "



Announcements

REFERENCES

Clevelond, G.B., 1975.londsM,ng ,n morine ter·

rOte terro,n ColifornlO D ' ~ ' l ! o n of M'nes ond

Geology Spe<:101 Report 119, 24 p

Dupr., WR. 1975, Mop lhowing ge-ologyond

liquefo",on potenhol 01 Quaternory depol,t.

in Sonto Cruz Counl)', Col,forn,o; U.S.Geo·

IogJ,oISu....ey Mis<;e.loneous Field Stud,es

Mop MF·648.

Grog9', G.B., 1973. Eormquoke o,hy,ty between

Monlerey ond Holl Moon Boy, Col,forn.o:

CALIFORNIA GEOLOGY, 26, no. 5,

p.l03·ll0.

Gr,ggs, G B. 1982, Flood'r>g ond "ope fo,lure

du"n9 the Jonuary, 19B2 ,torm, Sonto Cruz

County. Col,lorn,o: CALIFORNIA GEOLOGY.

y. 35, no. 7, p.158-163,

Grig9S. G,8. ond Johnson, R.E., 1979, Erosionol

proce..es ond ,1,1f retreOl olong lhe northern

Sonto Cruz County coostline CALIFORNIA

GEOLOGY, y. 32 , no 4. p, 67.76,

Gr'9gs. G 8. ond S o ~ o y , l . E . , 1 9 8 5 , l , ~ , n 9 with

the CoMornlO 'oost: Duke Un.ye....'Y Press,

Durhom, NC . 39 3 p.

Horp, E.l. Wilson, R.C., ond Wieczorek, G.F.,

1981,londslode, from the February 4. 1976.

Guatemolo eorthquoke, U.S. Geo109,,01

Su","ey PrOfesSlOnol Poper 1294.A,

lowson, A . C ~ ond others, 1908. The CoMorrno

eormquake 01 Ap,,118, 1906. report of the

Col,lornlO S'ole Eorthquake lr....e'I'901Ion

Comm'SSlon, Cornegle 'n.Mute, Publi,ohon

87, Y. I, Woshington, D.C., 451 p.

McNolly. K.C., loy, T P,otl,·Que,odo.M., Volen•

..e, G., Oronge, D. ond Anderson, R.5., 1989,

Sonto Cruz Mounto,nslloma Pne'o) eorth·

quake, EOS. TranSOC!lOns, ArnerKOn Geo·

ph)'Sl'ol U n , o n , ~ . 70, no, 45. p, 1463·1467.

Plol1<er. G., ond Go/lowoy, J . P ~ 1989,leuon.learned Irom the loma Prieto, ColilornlO,

e<lrthquoke of Oc:tober 17, 19B9 U.S.

Geologi,ol Survey Circulor 1045. 48 p.

Shokol, A.. ReKhle. M.• Venluro, C. Coo, 1., She,'

burne, R., S o ~ o g e , M., Darrogh, R. ond Peter.

sen, C., 1989, CSMJP strong·mol'On ,eco.ds

from Ihe Sonto Cruz Mounto,ns (lomo Pnetol.

Col,lornio earthquake of 17 Oc:tober 1989,

Coliiornoo Strong Motion Inll'umentOllon Pro·

grom Report No. OSMS 89·06· D;Yl,"on of

M,ne. ond Geology. 195 p.

Registration andCertification Examinations

E u m m ~ h u n \ by lhe S'a'e Iwart! of R q ~ i ~ ·l r ~ l I u n for G e u l u ~ ' ~ h and Geuphy"e"IS for19'Xl re \l'heelulcd a, r"'l"",,

G e " l . l ~ ' " ~ n Gcoph)"ei'l

Seplember 14, 1990

l,nj:'lneerlnj:' G e u l , , ~ . ~ 'Seplember l:'l. 11)9()

hlMI filmj:' elale f"r lhe Seplemlll:r 1990, 'X:lllunallon, May I, 1'J90 iP'U"rn:.rL .'/'IIe).

h.r appll,'allt'" fnrm\ c"nl ....'l ,hc Boam

"fftel'al 1021 0 Str",,!. Rlll'l1l A·IOO. Sacrn·","nl", C,\ l j ~ " 14 Phone (lJ Ill) 4 4 ~ . I'1211

14th Congress - 1990Mining and Metallurgical

Institutions

The Fourleemb COllj:'re,s of Ihe C.luneil

of M,nInl.! and .\1clallurglcal [ n ~ l l l U l l ( \ n ~ .orl.!an"ed hy lhe In"nul'on of Milung andMelallurl.!), "",I be b"ld In I : d l l l b u r ~ h .Scotland. July 2-6. 19\K1

For full d"':lil," f

lheC o n ~ r e " ,

a"ocialedplenu) and lecbnlcal ""s"on\, and leehnlcalwu", ,'()nlaC'

The Conference Off'''e[n\lllUllOll of r.-llnllll; and Me'allurgy

44 l'or'land I'la"cLondon WIN 4BR E n ~ l a n dTelcphlJll" 01·580 3802hx : 01··06·5.188

GSA/SSA Meeting

A JOInt llIeellnj:' of lhc CUrUlllcrJn S«'lonof lhe GeoICJg"al Sueiely of AmerIca (GSA)

and lbe Sc"molu!:t,cal SOCJel) of AmCrlca(SSAj ""II be held March 25-27. 19'JI InSan l-rJnel'co. CalofornJa

Fur Ill"re IIlformallon eunlaCI GSACIl·ehair RJ) Sullo\'an, Departmenl or Geo·

, , ' u : n C l . · ~ . SJn hal""""o Sla'e U I l l . - . : r ~ l l y ,San Franc.\Co, CA.(415) 3311·2061. "r SSAC,,·chalr. r . ~ " Wung, Wood"'·ard·ClydeCtln\UllJ1l1\. OaUand, CA.

H I ~ ) 1174·.1014

NAGT Spring Conference

The spring conference uf Nallonal A-'loOCi·al",n uf GeulCJgy T e a c h " r ~ . Far Weslern

Seellon .... 111 be held May 4-6. 1990 al C , ' r u ~C " l I e ~ e In A f . U ~ a . CalifornIa. A lwo·d:.yfield I" p will cowr lhe geologic ,nlerprela·lion uflhe Precambnan and P..lleOI.OlC

mela",d.,nenlary r u d . ~ , Cello7"ic lecronlcfeal urc" anel ml n.er.lI re,ourcc, of lbe SanlJernardlllo Mounlam,.

For addlllonal mfOrmalion cuntaCI:

0 0 . Trent. Geology Dcparlmen'C,lru, Collcj:'e. H o RRR

A l . u , ~ . CA 91702.

Second InternationalConference - GeotechnicalEarthquake Engineering and

Soil Dynamics

Tbe Second Inlernalional C"nference onc.:Olechnical Earlhquake Engllleenng and

S",I l)ynanucs, organi/.ed by 'h e Uni ......"nyof M"",uri·Rolla II I e<>operallOn wllh nllle

profes"onar cnglneermg and getJIeehlllcalsoc,elles, WIll be held m Sl. Lou'S, M"soull

on March 11·15. 1991

ro r n>Ol"C mf..,rmallon COlnaCI

Sbamsher I 'rl lhsh

Conference ChaIrmanOcpartmcnlofC,\,lll:.nglllecnng

U n l v e r ~ l l y of Ml"ouri·Rolia

Rulla, MO 65401·0249 USA

'lclcphoOle J I4·3414411\1Tt'lcfa.. 314·341-4729

SSA Meeting

The ScNOlulogical Soe.e'y uf America ....,11

bold ,he annu:t1mcrling Ma) 2·4. 1990 III

Sama Cru/, C"hfornla

I·"r mrormau"n eunl:"':

heel l'ollowdl. 1.·205Lawrence Li\'ermore NallOnal Laborah.ryBox IlOll

Llvcrmore. CA 94550

.. CALIFORNIA GEOLOGY All'" 11"10



-.

---••

•

Photo 1. Aenol v,ew of Moddt. Bultes, (OCM ""no oreo, K.," County. Photo courtesyof CoCo Mines. Inc.

Cactus Gold MineKern County, California

8y

JOHN l. BURNETT, Geologist

Division of Mines and Geology

cod

JAMES BRADY, Chief Mine Geologist

Cactus Mine

Sonc. the discovery ond wc:ce"ful mln,ng of

bulk Iow.grade hydrothermal gold ar , depolitl

,n Ne'fOdo during the 1960., 0 number of.imila.depoSIt> ho.... been Identified or>d m,ned In rhe

MOlove Delerl, BOl,n on<! Range, and COO,I

Range. prov,nce.of CalifornIa. thoulonds 01

ounce. of gold o,e produced e<Kh year from

well Colifornla depol,ls. Th, fine_grained gold In

these dlUomlnaled dopas'" con rarely be ......

""en under 0 mKroKop" ood must be assoyed

10 determ,"e rhe gold conrent. .. . edItor

INTRODUQION

The aC[I\C C ; ] C I U ~ gold nunc h IOCMCd

in the 1Oo'C,tcrn Moj:l\'c Dc'\Crt. about60 mile, lIorth orlhe ('ily of LO!> Angclc,.

and :lh,lull) miles norlhcil,t of the llWon

of Mopvc (Figure I) , The gold I l l l l l l l lg

opcrJlIon, arc;H Middle BUllc\. nn 1'0,

latcd peak of Miocene mle:mk rods and

Crewce()u, 1I1IrlN\1: I'QCl\ \urrounded byQuatcrn:lr) ,llluvlal dCp<blt, (Pho!l) I:

hgure 2)

Gold W,l',lirM nuned nlMlddlc B U l l e ~in 1 8 1 ) ~ (Tro\el :md Morton. 1962) ;md aj;rtlUp of ~ l 1 1 a l l I11lne\ continued IJpcmtlng

lhere until 1910. 1\'11111111; activity :It Mid·die Butte re!>umed during the Dcpre'\ion

:lI1d wa\ I:OntIl1UOIl\ from 19]1 to 1942

\\hen. during World War II. gold mining

\\":1-\ b:lnned by the fedeml government.\V:lr Production Board Limitation Ordcr

L·208 h:llted Of)Cr:ttIOIl':lt Middle Bunesand all olher gold mine, 111 the UnitedSlate\ !J.ccau\C gold nuning \ \ ;1 \ deemednon·e,:-cntlalw lhe w:lr eflim.

In 1979thc C:lelu\ mine prOJk'rty was

:Icquired by CoCa Mine!> Incoqx)f";ucd of

Denver. Colomdo. Commcrcinl production !>larted in August 1986. Gold production reached 26.400 o u n c c ~ in 1987. andthe current annual outpul h aboul 60JXXI

ounce!> of gold. Total projected produclion will be about 400.000 ounce!>.

GEOLOGIC SETTING

The we\tern Mojave [)e\Cn is a sHUc

tuml blocl bounded on the southwest b)'the San Andrea\ fault :tone and boundedon the northwest by the Garlock f:lultIUne (Figure I). Both fault lones arc

vertic:ll bre:lb in the earth'!> erustth:llhave undergooe Mgnificant I:lteml offsct

CALIFORNIA OfOlOGY Ap,,119'90

"



",-",CACTUS GOLD MINEG!!'O(,-"

\ "MOJAVE 000

• 0

oc : : : : : l ~ : : ' - T r o p l r ; ; o HIli

"Wil lows Sl Idn ll ' H I li '

*' LANCASTER

. . LOS ANGElES

•N"J

Mil"

.. . Figure 1. Generol I o < o ~ o n ond regiorwl tedonlC

.enlng of the Codus gold mine. F>gIJnl' odapred

from CoCo M"'e", Inc,

cant anlOllnt, of ore arc found in fault

breccia along these norlhy.e,t-Irending

l O n e ~ .

Mineralogy

A r e a ~ of IlItcnse hydrolhermal alter..

lion occur aoove and peripher..ally adJa.

cem to Mlme ore z o n e ~ . Hydrothermal

alteration occur, .... hell heated aqueous

Mllutions rise up through joinl.\. fbsures.

or f a u 1 l 1 0 n e ~ and change I11lllerah ,'00roch in the process. These altered l o n e ~,lithe Caclus mine aid in identifying ore

be,lring Mruclurcs. Alunitc (a hydrous

aluminul11 and p o l a ~ s i l l m ~ u l f a t c ) is the

m<ht common mincral within this alte.....

lion lone. Kaolinitc clay. illite clay. andhematite (iron oxide) ab o occur v.ithin

zoncs of hydrothermal alteration.

Figure 1. Geologv of Coctus gold mine. Middle Suite•• ond nearby I.olure•

Cre/.,,,ou.

O fl MonlOnif.1IJ/o

Free gold and sll\,eroccur:lS subnu

croscopic grains and are a s ~ o c i a l e d with

quartz (silicon dioxide). pyrile (iron ox

ide). ar.'>Cnopyrite (iron arsenic ~ u l f i d e ) .and iron olt ides. Some ore l o n e ~ are quite

Jeep and cltlend below the d e c p e ~ 1 explo

.....tion holcs. All of the gold orc at the

mine site occurs in or ncar a coop..c

grarned rhyolite that forms 'oC\'cr-11 intru

,i\'c domes. In ~ o m e arcas of thc minc.

O. I ounce of gold ore per ton can be

found 20 feet bcnealh the ,urface. al·

Ihough no deleclable gold lIIay occur al

Ihc ,urface.

--.

•Willow. Spring. ~

N , 'J' 11ofl1..!

(1''1''1::.::::1' Mloc.n. Pvroclut1c.

IMloc.". VoIc.nlC\DonN••

F I_••nd Plug. \

\ Willow,Spring., \Hlla

IMiddl ' IkJtl••

Thc richest ore at Middle BUlles i locailled along norlheasl-trending fault

lOnes. One such ll11neratiled fault lOne

contains Ihe (aClO'i \t:1ll that was the fo

cus of mmlllg aClivity m the 1 9 3 0 ~ This

p:lrticlliar fault lOne al.'iO hosls the Shu·

make pit dCpo!litthat is currelltly bemg

mmed (Figures) and 4) . Other ore zones

at the I11l1le occur on parallel northeast

trclldmg f a u l t ~ . The.... mlne.....llled fault

lones II I lUrn arc inter!oCcled by north·

....esHrending cross-cuHmg faulls: ,ignifi-

CA.LlfOIl:NIA GEOLOGY

CDlbblcc. 1967). The G:lrJock f:lUh. the

c!o-.c,' of Ihc\C IWO region:!1 fault zone!>

to lhe mine. b '\Cvcr.. lmilcs north of the

Cacw, nUllc. Major geologic structures

.... i lhin Ihe mine area. ,ueh;t) nOnhC:lSI

trending ore ,"crnl>. run parallel 10 the

Garlock fault lone and suggc'l a regional

r d a l i o n ~ h i p .

Although Cretaceous granitic rocks

and Miocene volcanic roch arc [he only

c . ~ p o s c d u n l t ~ \\ithilllhc mine area.nearby outcrops Hlcludc S(:\"crnl tyJ>C' of

metamorphic rock,. Teniary ~ c d i m c n l a r )rocb. and Quaternary basal! flows and

sediments. These diverse rock I) pes indi

cate thallhis region h l l ~ been tectonically

:Jctivc in the geologic past.

Structure ond lithology

Quam'. mon.wnne f o r m ~ the b:tSCmerll

rock beneath the mine si te and is overlain

by l a \ ' a ~ and p y r o c l 3 ~ l I e flows. The

quartz mon/onile formed between 85

IlIIlIian y c a r ~ ago and J 12 million yearsago and b a 8runite-l ike roc" containlllg

equal a m o u m ~ of o r t h o c l a ~ and plagio

clase feldsp:ns. Imrusive i g n e o u ~ domes

form a M:lI1i-circular feature e:dending

from Middle BUlles and Soledad Mountain

on the nor th 10 Tropico lIill and Willow

S p r l n g ~ Hilh on the !>OUth (Figure 2).

T h l ~ M:rt1i-circular fealOrc may represem

a ealde ..... that formed when a s c n e ~ of

concentric f r a c t u r e ~ resulted from a

collap,ing \'olcano (Figure 2).

..



, ,• Figure J. POl'f1on of tl>e W,llow S p r l " 9 ~ (7.5-

/, ..

-,'m,nute) q\lOdrongle thowing MIddle Bulle. and

, J 'Ioc:olioo. and nome, of hilla,ie m,ne_, Line A·A',nc!,cole,lcxollon of geologK cron-slKhonV .. .how. on Figure 4.

/,

..

\, MINING AND GOLD RECOVERY

.- c

...,"I-"lmti ... i..hmlnrc bodie_ .....ere idemified

,.I"

and mapped u ~ i n g Information derived_.• \ 10

fmm a drill ing program. Currem mine

development is b) open pil m C l h o d ~ and

M!oohj B U T T ~ S IIlcludcs ~ u c c c s s i \ ' c benches thai arc

pl:lccd at 20-fool ..eTlical inlcnals up the

• "pll wall. The 3VCr:LgC ore gr.wc allhe

-/r !JlInc b O.Q.l5 ounce of gold per Ion:

, -1' f'=' -..,..- - varying amount." of ~ i l v c r ore abo occur., - "o r example. of the 6.168.000 tons of ore,j,

<f' ...- milled from the Shurnale pit. the average, gr,llk of gold was 0.038 ounce per Ion, , .;;::. and Ih.: ;I\'cr:lge gr.ulc of silver w a 0.4

ounee pcr IOn .

y " ./""\",. t ",- ._- - Gold and si!\'er rreo"er) h aOOUI 71

Ipercent of the tOlal amount of p r c e i o u ~

II l lcwb I!lCM;nt in Ihc ure. Mined ore i cru\hed, rni.\ed "ilh lime and ccment.

I

'"then mo\"Cd 10 th(" cyalllde heap•.... or, ...(J'- . .) . -

1 ---' - r -- - leach pile via a con,eyor bclllhat i , , ~ p r . l ) " e d "'ith water. The 1 I l 0 i ~ t C l l C d cc--"".ii.. i / ---H ~ : -....:-, ... mem b i n d ~ the fine ore parIides and aids-, I 3000 tt ; percolation of the lC;lching \olution.

I,-

II .

1-- •" ftgu,e 4 Generalized geologIC cross-sedlon 01

lhe (OCIvI gold m,ne a' e deposl"- Middle 8ulln.

Kern Counly See f,gu'e 310' l o e a ~ o n 01 ero..•ecllon A-A'.

Alaoklng Norll\eut A'

3200· ...

2600· ...

C...lIFOI1N .... GEOLOGY ...""lt99ll

Trent

Tlbr

87



A Page for Teachers

Earthquake Preparedness Education

I ~ ~ f ! , ( ~ ..... ~ .

IPlans toMake

SCHOOL PLANNERS r " ' ~ " ' , 11>. r ~ , , , C1<n'or,.nd coll<"" .....d h' ",er.,e'<If. ""',.,. I!am;,o"nl "'J1hq""u la >UCh 0" "",n,."'_

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et>n<lU<1 ··dl<1" .0'''' .noll>oW·' d"l[,II,,,,,,.,,., ou, """'",Id"hl."n .n<l ,1><" '.m,I"" ......, -ne ."f."",,,,,,,,, on<! ed ...."o" ' ' ' ' ".f1hq.. .k loOl'<ty_

",<!,'''ed''''" ,"".,n,,,,

, ; " ' , " ." '.... <>on l > ~ . 1"'' ' '" , ~ """I"< .nol,m!",",",I ' " ~ h < .d ...."o" . .mp.o'l" 'n Ap"l anol ' ~ ' o " s " ' ' ' ' ' lhe"'"' ~ • < , · , J I ' I d u < : ' m ~ • "' ....... d"lI.o k> l .""",<11<) rla ....n<! • 1>W""'Io"t • 'f'U".1 _ '" " , h < : > < ~ """,mhly Iv llot",oa:<lurr. M.. ~ ..... ...... """'"'u......""",y,,...... ell""", of •• nhq...k> an<! the ,ml""lOnce of ,..."'_I.... ""'"•. ",af<h .nd ''''''''''' ."" ' ' ' ' ' .nd II.>! 1"<'J'N""'"

a,d l<clln..,...... (h>I pl."",n,_ ._

.......,ar1 l·'ou, • IMpb"", ",<po.<d""", ,,,''''....._.' h,p t.. lll< OJ<'"<OIl ,... """".. O f of 1''''''8''11<) Set,,,,,,, I,n ) tN. " , , 1 o < > ס I

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• I"""""",.., , . l l "'Ik.......offan<! ........"" I" P'''I'''''' 0""".'Y ,n',>tm.,_.n<l fin-t 1M! ",pp1,.,.

.a"lIq....u " .....,.<"q pI>" I", ''''''' bm,I"" • ""'"....... ~ l I < k 1 "'p-I" . . . . ."hqUIl« I " " P O ~• Son<l'''1 ."k"_,,,,,, "",,'" ,'" po.<"1> 011 ''''' " , , , ,.. II'>

".hohl ..... )'tou. " ' h < > < ~<"""""'1' pol"""""n<! I""",,du,n • C,,,,,,,,,,,'.. ,.._.., "''''''''' ,<> ...... -.. . ", 1""

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• (. "" ".....,,,g ,n·",,,,,,,, I.. ."" " ...... ~ , " ' ' I ' ' "" II"" IM!. GlI,I"",," l.",... ....... "'.poredness Monlh ...........""'I.. . II\;O".I\<m.,,', dom.,. ......"mc:n' .."d "''''" . . Of'P'"'"""Y 101 In<he,,,. I""""'poh. ".ff...""""...,,,bl<d lopon I", "" ..... " ..If 1"'"''''', .n<l rommun,'y ,. .d.", 10 "BEATlll1 OlJAKE.-

Eanhquake p r e p a r c d n e ~ s education isimportant fo r gmde school ,Iudcllts

in earthquake-prone areas bccau'>C a ma

JOr carthqu;lke ca n be a trJunmtic experi

ence fo r C\'cryonc and especially fo r

children, The tmuma and . of cour!;C. the

loss of life and property ca n be signifi

cantly rcduced by prep;lring fo r an earthquale disaster, SewrJI tools thllt are

aY.litablc to aid teachers in Ihi!. p r o c e ~ sare described here,

£ { l r r h q u ( l 4 t ' ~ : A r..ucht'r" /'/It'4I1gt' for K-6

Grallt'$. a CUrriculum gu,(1c (1c\'Clope(1 by Ih..

Nal100al SClencc T c a c h c r ~ A , ~ o c i a l l o n(NSTAI for Ih .. Federal EmerJ!enc) Manage·

ment Agcnt') (FEMA). Thi) pactalle ,n('\u(1..•

malerials aboul both lhe ph) 'slcal phenomena

of ear1hquah-§ an(1 s:afel) m e a , u r c ~ a chil(1

can lake bi:fore. dUTlng. and afrer a quale

The gu,de reeognru. Ihal yOilng . l l l ( 1 c n l ~learn bcM when Ihe)' arc acm...I}. ph) ' lul l)

,n\'oh'cd and therefore ,ncludes §uggt.l'Olb

for many hand§-on c 1 a ~ . r o o m acll\l!leS, The

280-page paclaj!" conta,ns ~ , un11'. di , ided

inlO lhree !lra(1e l e " c 1 ~ (K-2. 3-4. S-M. All

unll. ' lIIc1ude background maIer,aI for Ihe

leacher: a >-cope amI ~ e l j u e n c c chart; maMer,

for producing lran)parCnclc,. hanlloub. a"d

" , o r h h c c I ~ : . t n d h M or m a l c T l a l ~ andrc-.ourcc,.

FEMA d l ~ I T l b u ! l o n I . l ,m,l..d 10 onc frel"

COP) per ~ h " " , l "h,le Ihe 'uppl)' lasts,

R e q u ~ ' b from Icacher,. wrlllen on ~ h o u Jlellcrhcad. should be d,recled 10 MaTlI)n

Mceab<'. Earlhqualt b!ucallon l 'lannmg

"'oJec!. FEMA. 500 C SUCCI. 5 W. Wa,h

,nglon. OC 20472 Smgle and mulhple ."Opy

r e q u e ~ t s from uther ~ r , ! u p ~ :lt1d lIId"'lduah)hould be ,enll" N S T A . I ' u h l t c a l l o n ~ Ocparl.ment. J742 ConneCllcut A\"Cnue. N W .

W J ~ h l l l ~ l o n . DC 20009 Cop,c, from NSTA

coo;t SI5.00 eal'h

f;"rtltq","':r Pft'p<u<"h,t'ss Aon'l/Ir, fur

ChIld Curt' 1'r<JlId<,n. publl ,hcd b) Ihe BayArea RCII-Ional I : . a r l h q u ~ l e I'rcparedne"

ProJecll8AREPP) and d"lrlbuled b} Ihc A ~ W C , ~ t , o n of Bay Area Go\,crnmcms IA BAG).

" a plannmg guide 10 a,d eh,ld e ~ f C pro

v,ders ,n (1eH'loplllg an eanhquale pl:ln Ihal

meet' an lnd"'ldual cemer\ unique needs

The gUIde l·on,')l. of ~ i l u : I 1 , o n card, Ihal de

,eflb<" whal nllt:hl occur ~ a chIld care ccmer

durIng and arter an l"arlhquale. aell' 11)

,heet, Ihal conlain InformalIon nccc"ar)' 10

conducl V : l T 1 O U ~ at'll"llles. " " o r ~ ,heel, 1<1 b<'

photocop'cd for lhe :Kl"llic, . and a re""urce

h ~ <If ":lnhquulc plann,nj! lnf"nnal'<ln

""ure.. ' The pl"t1tllng a c l i \ l l J e ~ ll1cJudc ldcn

l,fyll1l! thc nced 10 plan. IdellllfYll1! :lctual

carthquale h..urd , . de\'clup,n!! roln and

procedure,. and documenllng lhe plan Th,'

p!ann,n!! pnlCc" rehc, on aCIl,'c ~ t a f f parl,cIpallOn Ilowcver. thc proce" remaIn, "mplc

and erreCl'''' all(1 any l l 1 ~ I , l u ..on "rovid,"g,heller and C ~ f e for chIldren "'III b<"nerll

fWIll u""g Ihe .... malcrial,

A copy "f 1:./lrthqullkt Prrf><jrt'd"'·H. cata

10j! llem no 1'1l9002IlAR. I' S700 plu, SI50

for p,,'lagl' and han(1It"g Send or<kr lU

AIl,\G.I'.O Bo, 2050. Oalland. CA

9 - l 6 O . \ - ~ 0 5 0 . (4151.\64-7900.

NCEEH fllbfiogrj,pl,,' of /:-"rthq,wkr £11,,

cIII"mMIJ/l'rl<lh. b} Kalherlne E.K Ross.

publ1'hed by the Nalional Cenlcr for Earth

quake E ; : n ~ l n e c r l n g Re'iearch (NCI:;I:.Rl, Itsl'

re,ource malenal, fur leacher, and adm,n,,

tr..lor. to starl an earthquake educallon

proJ!rnm or leach a Illore detailed Ic',on on

eaTlhqualc'. ,,,Ic ..noc,. hunanll'. a"d plalc

l e l · l O n i c ~ . Curncula. softwarc. and supple

memal informauonal malcriall"ls arc pro

Vided for lcuchers and parenls for usc III

klll<krgartcn Ihmugh nmlh gradc clas'ie'.

Many hlbhogrnphlC Cllallon, HlClu-dc read,ng

Ie"el, and length of boob. T e l l C h e r ~ may

obla'n a free copy by wrlllllg to Ihe NallOnal

Ccnler for Earlhquale Enginccrlng Re:.earch.

Slale UnIVCf'lly of New York al Buffalo. Red

Jadet Quadrangle. Buffalo. NY 14261 f(e·

q u c ~ l T ~ c h n l e a l Repor1 NCEER-89-Rolo; u\c

school leHerhead.

L"m<t Pr'ew. C<tIt/QrllW. Ear/hqlwAr: A

Col/retwll 01 Vitlro Imagrs. produced by lhe

US <kologlcal Survey. I' a 53-mlnUle

vidcOlape rdea.cd:L'o U.S. GeologICal S u r ~Open-Fde RCpofl90-12-H. CopIes may be

obtalncd by ...rlling 10 Vidcotransform Inc: ..

245(1 F.mbarcadero Way. 1'.1.10 AllO. CA

94303, For further ,nformal'oo contxll)Qug

l'm-e. U.S. Geolog,cal Suney. 345 Mlddlc

f ,eld Road. Mail SlOp 225. Menlo I ': Ir l. CA

9.\025.(415) 329-4164

CALIFORNIA CEOlOCY Ap"i 1990



If . ,uJOf cal1hqu.ke .. .ue l 'n)'OU• • ,oa .oda}. f"U ' ' ' 'Ih, be ",·"hou, d"«l a""st.nc:c: for ap 10 12 hou",. A'e

y.... prcpa,ed to be ",If-suffo<>on" I. ) ...., f .m,ly? v...., ""'Ihbuf!w.<od·'

STORE EMERGENCY SUPPLIES

INDIVIDUAL, FAMILY, HOMEAND COMMUNITY PLANNER J

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lIome I',tparrdnessAfle• • major earthqua"". ekct''''''y, ......'c ,. • "oJ p. ma} be ou, of "',,"'ICC. Eme,gell<)"Oll ma} """ readl)'QU

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Community I ' r " p l l r e d n ~.. ~ u " c " 'ha' k>c-..I orp"".,oonl of ",IIl"h you .,,, •

men,"", unlk-nake alopC<1lic pr"l"'.edne>s p,ol,a'" or

l<'Iu"" "1"""'" tr. ,n,n, '0 be of . " ' "•• "" " ,n.be """n'

of. d......l ln ' e a r 1 h q u a ~ ".. 0.1"""'" a nc:'gbborlM)Ol! ea,'hqu.k" pRpa.ednc:"

F""·.. C.-lu<'l ""'"'"1 fOf nc:,ghbofhood . ."ukn.. ,n p ' ~ .

I ' . " ~ d , , , , " ' .fi,., al<l, fi,e wppr""""'. dam,1I" .' .... 'nlCn'.n d ",.roh .n d . ~ " " " "

• , \b""a'" e..... '&<,"'1' f<J<J<l. w"..,c, and Ofhe' .. .ppl",•.,nc:lud'''1 ""'d"" .... fi"" ., d l,' and do,h,n,

90 CAliFORN'A GEOLOGY Ap,,11990



iT

Protect

To prevenl Illjury 10 your family :Illd minimize damage.

SECURE FURNITURE

•

-WirDr'-'""--

~ b l ~ i a I > N_ c I

Cabt""l .... ' c 8.-ackc1$

'..:oS sac,",)1 ~ " l l t . a d S c ........

lOOkNudd

SC' ·d"""Ila"' .

"..C,esant .....,.""h

"bod Ttl'"Small Nalls Of II"",

s.c..... / toob

C.bindSInstall p<><.I''''' C8lebln& blelle. Many ""....,oons arc

. . . . .labk a , hard...". c 51'"''''

Opt'n S h ~ l n slallall Bua,d I(T_ ~ l f . Of 'Mul l ..,GOd lrIm '" ' front

of .helr l'l:ace b e . ~ y obJcct> "" lowe. ""","' \

Tall t'umitun'In.tall IMW ~ l b , a c ~ . " bt ......n ("m,I ,, '" and .....11

.rud .110f' (Tht -I.. bracket .an hc ,"".lk<l "' ' ' ' ' 'cd,;(I ,t ",II he hodd<n f.om ....... J

lI.nginx P i f l u r ~SeT...., hooh ,nil' wood "",mben only (.Il.d 01 cellIni

JO"I.J. <:Iooe hoob """" for hanl'"& poet.. ."" '0 pre_venl the" b1hni

_ ~ " " ' E . " . . . . ., 101 '_ . .._100.,_,("

PRACTICE EARTHQUAKE PROCEDURES

Ear1hquakr ')rill

Enroll"S" yoo. famIly and co-..o.kcn 10 p"rtl<,parc ,n

eart"'tuak" linn. I:."""IC"'Y p<OCflIu,r. ,lIQuid b<: 'c ·_d and p t K ' ~ pcrW)docally.

PTKlICC ,akin. co",r:

Prxh"" ' . ~ , n s a ) " ' " . . ,f In n " h q u l ~ ";crc , ~ k , n l !p I_ n.t> .... 'II makc 1"'0f'lc: ....... 'e of !he: ""Ies' 1'1""'"'01 ,h.", ,mmedi.,e en"ronmenl

I'B<:IICC nllm.,

""'alk ,h"""Jb ," " poosible est.pt ro...., . from )'QU'

IM:Nnt Ind "OIk p I_ C h « ~ 'O"'e ,f 'he pl.nned e",U3re e"'"'. Ind ,f ,hey _kl b«ome blocked In .n

nnhquake

1'n<:1,,,,, . h ~ " , f f ,I'n<:,,,,,, 'u,n,n. of f el«t"a'y and ..... 'e. . . YOU' ""me

Ind office lie 'u.e e""ryor>e <:In do ,lot> quoekly. "'now""'"' '0 'u.n off I I ' bu' t:Io no, """"ICC ,10.. s'ep (Once11' ' ' off. fen . .fe'y ,ea"""•. only)'OU. ulllny <:Ompany

""""kl,u", II bac:k on.)

Re.-i_ PDlil-Enlhquake Plans

Check and .cnew I" ....."io;>ns

C h t t ~ IUJ'I'ly of eme,seney r""" Ind ....Ie' Chttkmedoca",,". lint .od m"Cflals. for .11 memb<: ... of ," "hou;ch<>1d ,ncllHhnc ,be ch,ld.cn. handoe.l'f'«llnd

e1de,ly. Rcpkn,sh upm,d SIlpplH:' of food."" e

•.n>e•.he,ne. fi,e . , .".....rshtfS.1f>d !>;olle"",

II"""",," f.m,ly plan'lie_leW 'M '....,.,..,..btluo esofe.h fam,.y member ahe,In urlhq.. .ke. Call 'M desoVt.,ed «>nun pefWll OUl·lOde of 'M a'ea '0 .cm,nd IlM:m of ,""" tolt. lie.....,...plans '<> I""k "I ' child,e" and ekttk 'n,h sehools '"dlty (:I'e ""mefS ,<> en.. . ,e lhe f.m,ly plln .. ",II

"PP'optllle

II""..".. rommunny pla'"ConlXl )'OW " " ' P ' - ' pe'lOdoeally H) ,e""'"" earlh.

quake p l l' " C"" ,. ." )'OIlI' I<ocal Office of """"IC"'"5<:",'''''''' fo, In upda'e on ," " 10<:11 eme,.oney pl.n

en .....e lyou . counl)' orcil) ' office of Eme'l(e..cys",n-;"'.. . o r ' he Amerlean Ito:<l C....... for mo. . .i..lonnat'o .. on how you "" .. MREAT Tilt: QUAliDoi'n., . . ·!

OlifORNlA CfOlOGY 91



MAMMOTH LAKI:.S SIERRA. A Ibnd-

h n u ~ fur R ( ) a d ~ , t k and T r ~ 1 I bfth b.hllun

/I ) U e ~ n Rmehart. Uden Ve'I"I, and BeHit10 Willard; "d'led by Genn) Smllh 1989Genn) Snuth H " , , ~ , . A"a,lahle from Fro"nd,

ufthe Llbrar), Maml1lolh Chapter. I' O. B o 1-1611, M:lIllmuth L a ~ e ' . CA 935-16 Jill P

51195 !Induoc, l a and f l O ' t a ~ l . " I , papcrhad;

The ~ u l d e : c o " e : r ~ Ihe: fIfty-mIle pumon uf

the ea'tern ,Iopi' of the S,crra Ne'"dda Ihat

~ t r a d d l e , 1111!hway 395 bct"cen Sher"lQ

Summ,t and Cunway SummIt MO)l of thearea de'>Crlbcd III t h l ~ h a m . l b o t , ~ I' wnh", lhe

In)o Nat",nal h,re,t

In the R o a d ~ l d e ~ !>Cclion. poInt' of imere:.1alon!! H,!!hway 395 and alon!! "d e road,

hr.iIIM:h"'8 e:a\l and " e : ~ 1 melude .lune Lake:,Lee V,non8. Mono Cmler,. Red Mealio", theMmare:b. l>C:vll, l'mllllle, Convict Lale.

McGee: Creek Canyon. In)" Crall."rs. and

Llltle: L a k e ~ Valley. The Trail. ,\.Cellon foc u s c ~ on lhe Illgh SIerra. an area lhat i read·ilyacce."hlc Tip\ are g,,'("n for wildcrne"

hike•. induding mformallon about flI:',mlls,

map•. lrall<. and "'mountaln·wl""'" s;ofcI)m e a . u r ( ' ~ .

Book Reviews.... "',..... ,. , '",. "'\""':',

II.ooh revIewed li t t h l ~ leetlon 0' " nol availoble fa . p U f < h o ~ e From OMG

Aenol view 01 Green Creek m O ' O l n , , ~ . These lateral moralnt'!;, on the eo,1 slop" of the S,erra Nevada afew mil"s north of Conway Summll, outline Ihe poth of the lowe, end 01 the ancient 910<1e,.P/lo'o by Joitn S. Shellon.

Mammoth Mounroin, T h i ~ mounloln WO l bu,lt up by len or mO.e mojO!' volcanIC e.uptions rhot occurredd"n"il the pe.iod f.om about 200.000 yeol'$ ago 10 o.ound 50,000 yeo.. ago. Pharo by 8ev 51.......011

Addlllonal (calllre. oflhe b o o ~ ,ncluOcchllplns on the g"ology (completely revl<cdl.

clImate. fore<1 communllle:" ptam and anI'I11all1f". and h l ~ t o r y . all "H,llen In l a y m a n ' ~languagc Beautiful photos lllu_lrate chapr",..

"n "olcanoc, lfire:). ,Iacle'" (iccl. and m",mg bll"cr), Maps oflhe arclI are found onlhe ,nside front and b a c ~ covcrsTh... chapter on gcology ~ u m r n U I I _ e , the

paSI hIstory and pn>\"de' dues lIOOll1 th"future Th ... folio",,,,! cxcerpl , from

'"The l a n d ~ ~ ' a p e loda)" (p. 11-1-116)

While r e l e n t l e ~ 1 blfl ",ow uplift and 91ocIoIlOnwe." dromolo<olly chong,ng the 10ndKOpe,dromo 01 a more colo.l.ophic: k,nd W O 0['0 con

rribuhng 10 Ihe changing Kenery. All along theS,erro I.on!, and e ~ p e ' l O l l y in rhe MammothMono .egion. volcanic erupllons - many violent- occompan,ed the foultlng along the .onieI.onl. Although .perado< volconilm along lh. en·hr. Sierro Nevado hod been going on 10' a longlome, local voIconK: actIvIty , , ~ c o l o t e d ."markoblydun"" the ke Age. P.ec,,",o,", 10 lho mo'" ....ent_ re orvplionl north and we,1 of long Volley 01

Glon and Bold mountains ond 01 Son JoaquinMounloin .;dge - eruption, of loghl·coloredIova, pvmice, and ofh (rhyolite and closely 'e ·Ioled rocks). Ev,denrly the ~ u b l e r r o n e o n magmathat fed t h o ~ e erupl10rti grew in lize and en"rgy10 Ihe poinr tho! ,I could no longe' be conlo,n.d,

"

CAllfORNIA CEOlOCY Ap"II990



O _ I ~ Postpile. Thil bowl' flow e'upted about 100,000 yeol'$ ag o in Ihe vol.

ley 01 tI>e Middle Fork of the Son Joaquin IIi...... " filled 'he ~ o l l e y '0 a deplh01300 Ie.! fa. a d i ~ I o n c e of at l e o ~ t th'ee mil.". A$ tI>e boselt cooled and

,h,ank, lo,med a network 01 cmcl. which p,adtKed the Ii.... and si.·.K:led

columnl. lote' glociel'$ quottied owoy """,h of 'he flow an d planed aH and

poI..hed the kip 01 the flow. Photo by 8ev ShM!wn.

Mono Craters. The c,aters fonn a cha ,n 01 rhyolite d . . - ,

PItoto by Jlober1 C. Frompton.

About 730,000 y & O , ~ ag o an e.-mauS e",ption

cen'ered neor little Antelope Volley ..p1odedthrough o ~ e r l Y ' n g rock, ~ p e w i n g glowing lava

and blad. cloud. 01 enh high into the atmoophere.The ,"';mated volume 01 glowing pumice and o, hdisgorged il a ,IOgg. .. ng 150 cubic miles. (MounlSt. H e l e n ~ disgorged Ie .. lhan on e cub'c mile.) AI!he Ittupt>an continu.d an d intellSi/i.d, ~ u p p o r 1wOI progrelSivfIly r e m o ~ e d lrom the rool OverIhe enlir. magmo chamber, an d il collopsed,I e o ~ i n g lhe .lIiplicol deprelSlon now .nown o long Volley (old••o. The coldero e . t e n d ~ we.,·

.....rd from Ihe eo,t ~ i d e 01 long Volley 10 M,no.elSummit and lOulhword 'rom Bold Maunlain 10Crowl.,. Oom.Geophysicol meo,u.ement>, wppor1ed by

.ecenl drilling. indiCOle lhat the originol calcleroRoo. IOnk at leo,l 0 mIle, bul ,he colclera filled

ropodly will. e",pllng pumic. ond olh. Erosionand wbsequ.nl ~ o l c o n i c ..tnnion. h o ~ e bIon·•eled tI>e pr.Knl floor 01 lhe colelero so comp1.tely tho! not . ~ . n a remnonl 0/ lhe malerialIrom thaI ,"11'iOI cotody.m it e.po>ed inside Ih .caldera loday.lI it admi.obly uposed. haweve"s o u l h e o ~ 1 01 tong VoUey where it lor"" lhe brood

..ponK 01 the VOlcanIC lab/eland. I'" w./oc:e has_h e , e d 10 a . o ~ y ton color. hcellen' e.poIll''" 01 til. $Ofl. porOUJ, pumiceout, IOlmon_colored hiH can be .een in lhe roodc:ut> along US395 berw..n TOIns Place and a i ~ h o p . further e ~ i denee 01 Ihe mognilucie 01 Ihe long Volley erup'rion come, f,om Kon$Ol and Nebmlko whe•• , 01....erol Iocolili.. . o ~ from Ihe long VolI.y event

h o been po,,',,'ely idenlified. lAs" ;. a geologicterm 10' dull·siz. p o < 1 i d e ~ 01 vakonic ,oc:l.llnte.mi"enl eruption, within th.e colelero, but on ava.rty reduced 1C01e, IlIblequenlly filled much 0/the _ , 'e rn hall 01 Ihe colelero with ....Iconicd o m e ~ ond lava flow, o ~ e ' the ne.1 600,000y.oo.

o...rIapping tile 'fO""'9"r erup'ion' within th.ecaldera, a cha in 0' n_ ~ o I c a n o e . began 10propogote along a north-KIUI/lline ""endingfrom Mommath Mounlain fa< 30 m ~ e ~ , Ih.oughIh . Mono (raters 10 Mana lok •. The oId.sl andIo.ge" 01 the.e young ....Iconee. it MammothMaunlo'n, 0 compooile dome buill piecemeol byrecurring ~ i l C a u , e.lrvtions 01 gray 0. rec\disllkr.oa during an inl.rvol of 180,000 yeol'$, beginning oraund 200,000 years ago and ending50,000 yeal'$:r.;. The Iova iI o p r i n ~ wilh ',nycleo' 10 whitish elelspo. c r y l t o l ~ and sh,ny bloc.110•• • 01 mica.

Ileginning '-0,000 yeo" ago in lhe north atMono (<01.1'$ and occurring rno,e Or less randomly therealte, 01 varioul p I o c e ~ along Ihe.nlire north-south line. tile choin 01 youngvolcanoes erupted spo.adico.y. Unl,.e lhe longVolley eruption. which left a gill"'nl>c depr..sionO' it> ~ i g n o h J ' . , "' " \'OUng ~ o l c o n " , " buill con' P i c_s do ..... '0 cOlnmemo.o'e 'heir <>clivi..,.Thedomet repres.nl th.e!ole.. and mo.' p o ~ s i .. .phcne of th.e volcanic proces•. They we,e pr••ceded by .. p I o s i ~ e " r u p l l o n ~ tt.os propelledcloud. 0/ pumice and o ~ high in'o th.e prevailing

winds lhot d i ~ l r i b u l e d lhe d.b," widely in 0)1

di,ectiont, bullelt the Ih'ck•• t occumulotion,"""",by. AU. Irom one of ' h e ~ e e'uplions hos beenidentilied in meadows as 10. away o. the ~ o l l . , .0/ the linle Ke,n, 110 milet $Outh. Th'ee 01 th.ey o u n g e ~ 1 dom.s, which ore w e l l . ~ p o s . d andreodily accessible, 0 '. a! Glo.. ond D&Odmanc,ee"; all th."" or . about 55 0 years aiel.llecenl .. .idenc. serve. 10 ,emlnd u. lha, Ih .. "

earthquok. one! volcano counlry. Thot evidence,gathe,ed .ine. the ~ i g o r o u ~ &orthqua.e ~ w o r m ~in 1980 and 1983, it bosed on: Ihe og.s 01 tI>e

mall r.cen! . f U p t i o n ~ 01 Negil 1 ~ l o n d and IheDeadman do"",,; geophysical do'o lha' can beinle'Preted to indicol. I h. p e....tence 01 a ,.,id·uol magmo chamber beneolh Ihe caldera and Ih .

p o ~ l i b l e m()Y.menl 01 new magma 10 depth. 0 '.hallow o. 3 .ilomele.., a SO cm uplih 01 th.e

ground ~ u r f o c . ; and th.lfl'Otrnodic "emol'$ from1980-83,0 peculiar pallern On a •• i ~ m o g . a p hthol iI beli""ed 10 indicot. th.e movem.nl ofmagma. There it no reason to bel...... thol thi. ,,,.gion'llong hitlory 01 e o r t h q u a . e ~ o n d . . . . l c o n i ~ m ,• • Iending bock inlO onliquity '0 0 remale '0 com·prehend. has abruptly end.d. FOr1unol.ly, during" '" pres.n' period 01 ,eloti_I,onquility, we can.njoy and r" .. .1in the beauty crealed Ih,oughout'hat violenl h i ~ l o r y . And w. con /",,1 secure 'n lheeden. . . .. nelwon 01 d e ~ i c e s lhol continuallymonilor chonge. rho, could indicate tI>e begin.

n i n g ~ 01 ,enewed oc:livity. AI lhe some lime......will do well 10 .emembe. thaI I h i ~ it but on inl. r ·

.....sion In Ihe ongoing production 01 high dromal

CALifOIlNIA GEOLOGY Aprol 1990

"



Eonhquak.

More Book Reviews

1"l1IrnOllo"ol Jouf",,1 Journol

FIFl'EEN SECONDS, Tile Grellt Cal.for

nia Earlhquak.c of 1989, A I to IkncfilEanhquake Victims. 1989. The Tides Foun.dalion. 15 Seconds ProjccL 1388 SUllerSheet, 10th Floor. San Francisco. CA 94109.

120 p. $19.95, paptr coyer.

People wllo lived through lhe October 11.1989 '-"rna Prieta earthquake arc: tne focus of1his book. II is a collection of full·p:.gc pllo

togr.tphs. both in black-and-....hiIC and fullcolor. which rc:('ord tile agony, pain. and Ul l l '

male strength of the people who endured .hcquake. The dc....Slalion - lhe 6a)' Bridge,the damaged homes, and the: raging f i r e -

is also recorded wilhin these pholugr.aphs.

QUOIes from primary sources (rircfighlcrs.

r('$idenls, civic leaders) accomp:lny the

photos.All proceeds from the: sale of 15 Seconds

are 10 be donated 10 charities dedicated C'.tclusively to the immediate or Ions-term relief

of victims of the quake.

Earthquak.

TIlE QUAKE OF '89. Edi ted by the News

St. ff of the San Frnocisco Chronicle. 1989.

Chronicle 8ooks. 275 Fifth Street, San Francisco. CA 94103. 114 p. $9.95. soft cover.

Stor ies or the October 17. 1989. earthquakein northern California are recorded in this

phoIo-essay. The book IS orsanized intoSCW'n chapters shock, confusion. horror.

rescue. angUish. regrouping. and hope. Over100 photos. a ll in black-and-white and many

page-sile, convey the dT1lma of the event.

The accompanying narrative further adds to

the drnma of the evenl.

AMBIO, A Journal of the Human Envi

ronment. Royal S""ed,sh Academy of SCIcoccs. 80... 50005. S·IOJ Stoclholm.

S.....tdcn Copies a..allable H' U.S. from l'ergamon Prcss Ltd. Falr .. ie.... l·ark. Elmsford.New York 10523. S43.oo per year U.S .. on

eluding airma,l postage. $ 125.00 per year In

stitutIonal SUbSCrlptlOIl ($237 ,50It"'·o )"Cal"l;).

II I ~ S l > C S per year

PUbliC awareness of and IntereM II I envlr<m·

mental llrOlection and planned usc of nalUrdlresourcts havc dra....n tncr..a'lng allcntlonduring the lasl dccades. The environment I no ..... an IIrea of general conctrn Major tllvi

ronmtntal concerns. such as shifts l1l ,tralo

splteric 01.one, grecnhouse .....armlng of thc

planet. acidificallon and defore,tatlon. arc

now issues of nll1l0nal and world polll'CS,AMIJIO publishcs rccent won tn the Inter

related fields of cn .. ironmental management.techoology, and the natun>! sclCoces. II

focuses on Significant developmcnts in thcfields of cnvirllnmemal research, policy. Icgi_lation. and rdated aCll\"CS. to bring Impor

tant ,nformatlon to the allcntlon ofthc

intcrnallonal public.A r..cent issue (volume 18, number 5.

1989) contained articles on a wide vartety ofenvlronrnemaJly related tOpiCS. Coverdge was

intcrnallonal. Among thc topics iocludedwerc the m a s ~ death of harbor .\eals In Eu·

rope; t011C algal bloom in Nor",ay; catchment

monlloring In Czechoslovakia; drought In

Ind,a. woodfuel "tuaIlOO. Zambia: de\ilting

Lalc Chilika. India: and environmenlal contanlln:ltlon. Costa Rica.

One of the biggcSI ehalknges facmg man·kind is Ihe growing world population. Althe

pre.>e:nt roll .. of growth. ",orld populatIOn willdouble from thc preSCnl fi\'C billion to teO

b,lIiun within 50 years. Of the.\\: pe()ple.

ne:lrly 90 percent "",11 be living In c l t l e ~ In

Third World c o u m r l e ~ . If the Third World is

to consume energy al the rdte of developedcountnc, tuday. a fi\'efold trtC"re3SC m gh>bal

energy U'\C wil l be needed In Just 35 >'ears.Lack of energy. food and walcr. and o\"(:r·

crowding. and the lrtC"reascd threDt ofepldemic dlscaSe'S ar t socio-eeonomlC fKtor\

....pected to he,ghten the stress on the envi

ronment. AM 1110 comhtnes the diSCiplines

ofengtncer,. SClcntl_h. social planners. pollIIClans. and ~ o n o r m s t _ to Inform :tnd to help

aw n future cnvironmcntal dilemma,

AMBIO I a IIOlc .....orlhy Journal ""hlchdCM"n-es "' ,.... r e c ~ n n l u n and r e a d c ~ h l p

<III Damoged I>ou... in Oo!;Ia"d cou.ed by th . mag.

nitude 7.1 October 17, 1989 lama Priela eorth_quo!;e. Pfloro by Glenn 8o<cflo,d,

ROCKS & MINERALS. Hcldref l"ublica

t iom. 4000 Albemarle Street . NW, W a ~ h i n g ton, D.C. 20016. Annual subscription:S23.00 for individuals and $38.00 for institutions. Add $7.00 for subscriptions outside the

United Slates. Published bimornhly.

General Interest in mineralogy is the focus

of this magnine. thc official publication ofbOlh the Eastern Federation or Mincrulogical

and Lapidary Societies and the M i d w e ~ lFederation of Mineralogical and GeologICal

Societies. Feature articles on minel'1lllogy.geology. and paleontology are iocludcd, aswell as b o o ~ revie .....s. announcements. andclassified advertiliCments.The No\'CmberfOecember 19119 (Volume

64. Number 6) issue of the magazine in

cluded articles on "Amethyst sccpters.Salem. New London County, Connecticut,"

"Mass ulinclions: astronomical influence or

earthly causes?", "16th Rochester Minel'lll

ogical Symposium. contributcd papers In

specimen mineralogy. " "O f mines and mto:

a look lit art Ihat depiCl.s mining." "Throughthe 'scope; interview with Arnold Hamp

son." "World news of minel'1ll1 occurrences."

"Rock chips: some miscellany, p . ~ r t II." and"Spotlight on juniors: yesterday's juniors.tuday'S profl'Ssiooal."

Son A"d'eo$ foull, Sout"',n Calolor",o

SAN ANDREAS FAULT. Cajon Pass toWallace Creek. Volumes I and II. Edl1ed byE, Joan 8aldwin. John II. FOSler. W. LavonLe.... is . J. Kirk Hardy. Michael L. Raub, andMichael Rendina. 1989. South Coast Geolog

Ical Society.loc .. P.O. Bo .. 10244. SantaAna. California 92711-0244. S40.00 per SCt.

sort cover.

A set of two volumes ....as published in

conjunction with the South Coast ecolog,ulSociety's October 1989 ficld lrip.

Volume I consists of a series of papers onvarious aspects of the San Andreas fault andIncludes diSCUSSions on the hIstory of coocepts and studics along the faull . the ~ t r u c tUT1l1 features and problems associated wllhthe fault. palcOlectonlcs. neoteclonic, anddetcrmination of recurrence inlerVllls of large

earthquakes. and stress. snam. seismiCity.and prediction along the fault . Two blblio.gl'1llplties conclude lhis volume

f,om the forward'

"No oth.... geologic feature in Cal,/Of"'" ha l

been vn,ted a. much, studied 0$ inten....eIy. norraised 0$ m.....h controve,." O. l+ofI Son Ar>dreos

louh. for a complete and In depth cOWl'age 01

CAliFORNIA GEOLOGY Ap.. t 1990



Compl.te oddreSl form on n.. .t page

MAIL ORDER FORM

Price include.

posloge and IOle. tax

Fear thai San Francisco would lose its p0

sition a s lhe commercial hub of the wcst led10 the deternllnation of financial. industrial.

and commercIal insti tutions and entitles to

suppres. informalion about thts 1906eanh

quake dilaSler AI the same time l'TofessorJohn C. 8ranner. Geology Oeparlment at

Stanford University. and l 'rofeswr Andrtw

C. Lawson. Geology Department al Univer

su y of California (Berkeley). were trying to

providt scienliflC informal ion aooul the

eal1hquake.

Tile authors researched U.S . Army and

Navy records in Ihe Nalional Archi\"ts. death

nOliccs in Ihe daily newspapers of Ihe time.

Ihe deaths rcgistered in the coroner's records.

an d made a public appeal 10 conlacl rdatives.

dcscendants. and friends or those woo died in

lhe 1906 dlsasler to determine the e ~ l t n t of

th e loss of life

The book ha s 333 phOlographs. 321 never

published before. which lel1lhe Slory of th e

earthquake and fire. Reproductions of col

ored pos tcards and paintings are inc luded.

This book is a valuable addilion 10 lbc

hislorical record of San Francisco.

t 13.00

t 8.00

t 1.00

t'2'2.00

t3O.oo

t 8.00

S 1.00S 1.00

S 18.00S 9.00

S 7.00

Ir>dieole number of copies

SPECIAL PU8t1CATlONS

__ SPJ3Minerols and rocU. 196'2 . •• . . .• . .• • . . •• . •. . . . . . . . • . . • • • . . . •

__ SP60 Earthquake planning scenario lor 0 Magnitude 8.3 eonhquake on the

Son Ar>dreo. fault in JOUIh.em California. 198'2 . .

__ SP61 Eorthquak. planning scenario for a magnitude 8.3 eorthquol<e on the

Son Andr..cn fault in Ihe Son francn.co Soy Oreo. 198'2 .....

__ SP78 Eorthquak. planning scenario for a magnitude 7.5 eorthquoke on the

Hayward fouIt in the Son francisco Soy oreo. 1987 • • • . • . . • . . . . . . . . • .

__ Sf'99 Planning sc_r io lor a mojor eorthquah On the

Newporl-Inglewood fault Zonol. 1988 . • . . • . . . . • • . . . • • • • . • • • • • . • . . . . .

__ SP101 Technicol ar>d economic fecn.ib;!ily of on earthquake ""Orning system

in Colifornia. 1988 . • . • . • • . . • • . . • . . . . . . . . • . . • . . . . • • . . . • • • • .

•BULLETINS

__ IU89Mineral. of California. 1966 . • . • . • • • . • • . . • . . • • • . . • • • • . • . • • . . . • . . .

__ 8'206 Geology and are deposits 01 the Bodi. mining district, Mono COf,Hlty,

California. 1987 .

__ 6'208 2eo1ites in Colifornio. 1988 (new) .

SPECIAL REPORTS

__SR70 Sond and grovelresourc.s of the Kern RiVe<" r>eot Bokersf.. ld.

K.rn COf,Hlty. 1961 • . . . • . . . .

__ SR1l9 lol\dsliding in..-ine terroce telroin. California. 1975 . . • • . . . • • • .

lurchcd pa't eactl other for a dlSlance of ulltu

t"·cnty·onc fcet along Ihe Callforn.a COlI.t

The resulting break slretehed about 290 mtles

from MendOCino to Monlerey eounlles. San

Fruncl"Co at this lime 1"11' a city of410.000.

O n e - " ~ I h of the CIty was bu,lt on "made ......

f.lled land"

T t l l ~ ne .... history oflhe San Francisco

earthquake cuns."\ of Ihe follow,ng 'ecliuns·

Introducllon: The Great l:arlhquake: The

Great Fire: The I'ohllcs of D.saster: and all

epIlogue. The Future of San Francisco.

whIch includes a b"ef repor l on Ihe crfeeb of

the OcHlbcr 17. 19119 e a r t h q u a ~ e . There l a lso an c x t e n ~ i V < ' bibliography.

Many eye-witness accounts by people "ho

Ii\"td through the quake - police officers.

rePOrlers. a thlrleen-ycar old boy. rabhis.

and nllnlSlers - arc given. The book rclales

delails of Ihe dtsaster - lrapped viclims

dying in Ihe rubble of shabby lOOlh-Qf-Man.:et

rooming houses when fin: s"<ecps through

thc area: thc eataslrophic fat lure of San Fran

cisco's watcr supply: lQOllng: people camped

in oUllYlOg arells.

the growlh ond development 01 knowledge about

the fault, .. . feed Mason HiW. 1981 art ;d. which

is reprinted in this volume,

It was MalOn Hill and Tom Dibble. who, in1953,_,.the finllO propose in print t "of someroc.k unih hod been broken Dnd alhe' more thon300 miles in 0 tighlloIeroJ sense by th . Son A,,

d,eo. foull. Thi•• torte<! a con'rove"y amongColilOtnio geologists, j ,( ) ftI<l agreeing wilh Hill

and Dibblee, and some mointoining thot verticol

movement on the foull could e..plain the off.. ,

ro d ..nils.

Research",at un ...." i ' i••, omonglhem JolinCrow&ll and Perry Eh!ig. I Ind"OVOflld , indivjd\lOlly. 10won oul this problem and also many 0/

their lIudenn .rudittd the Son AndreQS 10 ...11 o. 0part of!Mi, M-S. and Ph.D. th,,,••. Grodvolly,will> occumulofiot, of dolo, fII01lgllologilts be

come convinced thot o. MuCh as 200 milliS ofright lotllra! ofhel hod <><;curred. In tM lot. 1960.

rhe theory of p10te ,,,daniel was developed or\Cl

J. 'uzo Wil..," propooed thot rhe San Andrea. i.

a lro",fonTl foull forming a part of the boundary

between the Pacific and North American Plot,",1n the 196(h ol\d 1970. RobertWollac. ol\d

orhen of the U.S. Geological Survey mode oignjf.

icont conlribution.1O the study of geomo<phic

fe.olu"" creal&d by recent .tipi along the SonAfIdreOi loult. The.. are particulorly well pre·

.......&d on the Carma PIoi. .. ln lhe 1970. an d

1980. Kerry Sieh 01 California IMlilute of Tech

nology ""Os the leading reHlOrch.r in eorthquoke

chronology, recurrence intervol" ol\d slip role1o

oIong the southern Son AI\dre<n foult Oi a rewlt

of hi. inmol srudies at Pollett C r ~ k . RoyWeldon

added to knowfedge of slip rotes by hi. srudie. in

Cajon Volley. At the so.... ~ m e . geol09i'l1 ollhe

Colifomia Dnrision ofMines and Geology (in.

duding Al60rrows, Jim Kohl., David B.eeby. HalWeber. or>d othenl dicI delailed mopping along

the HlCtion of the fault in Los Angelti County.

Stre.. . slroin, and Jeiirnicity along the foulthove been ,tudi&d by a number of r. . . . . .rch.n

and _mp l1 ore being mode 10 predict earth·quol<es. The Port.Jielc:l Earthquake Prediction Ex-

periment;' deocribed in officles in this vokome.H

Volume II is a fi el d ni p road log for the

San Andrus fault f rom Cajon Pass 10 Wal

lace Creek. Twenty plale5 al various scales

are inclUded. Aerial pho(os by John S. Shd

don enhance the fidd Irip volume.

1906 Son fronc,sco Earthquake

TOTAL AMOUNT ENCLOSED... . •• • . . • . . •• . ••. . •• • . •• .• . •• . . . • . . . . •• .• . •• $, _

PAYMENT MUST 8E INCLUDED WITH ORDER

DENIAL OF DISASTER. TIle UntoldStory and Phologr.aphs of Ihe San Francisco

Eanhquake and Fire of 1906. 1989. By

Gladys Hansen and EmlMt Cundon .... ith

David Fo ... ler. edilor. and Richard Hansen.

Pholo Researchcr. ClImeron and COmpan).

S4) Howard Street. San Francisco. CA

9 4 1 0 ~ . 160 p. $ 2 9 . 9 ~ . hard cover.

At ~ : 1 2 : 0 ~ a.m. on Wednesday. April 18.

1906. a diuMer struck in northern Califor

nia. The PxiflC and Nor th American plat.:s.

responding t o the geologit tension on Ihem.

COUNTY REPORTS

__ Cll Mines and mineral reSOUrC.s al K.rn County. 196'2

__ CR<4 Minesol\d mineral r.sources 01 Trinity County. 1965 • . . • . • . . . • • . . . . . • •

CAUfOllNlAGEOLOGY

__ 1yeor 11'2 iuuesl . . • • . . . . . . . . . . • . . . • . . . • . . . . . . . . . . . . • • . • • • • . . • • • • . . . . . • .

__ '2 yeo" 1'2<4 iJwesl . . . . .

__ Bock ;lSues (Specify volume ol\d monthllnd",iduol issues S1.00eoch .

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CALiFORMA GEOLOGY Apro.lm

"



SlATE Of CAUFORNlo'.THE RESOUFlCES AOE.NCY

DEPARTMENT Of CONSERVATION

CALIFORNIA GEOLOGYCAl.F<>NA 0MS<lN OFMINES AND GEOLOGY

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paid lIIall order or O\'Cr·lhe:-counlcr from

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The bibliography eorllau!S 6061111<:...reprc'>Cntlllg lhe: Ilo'Ofi of 521 authors

Most of lhe: enlrle'> arc JOUrnal artICle...

bullhe: blbhography also i n e l u d e ~ hool;.s.

el\lpllon report'>. ob!.crvatory serral pub-Ilcalll)llS. ab'i:trncls. and informal or un

p u b l i ~ h c d reporlS. Th e bibliography I divided into f ivc .'>Cclion..: (/\) rcfcrcncc\

lislcd alphabetically by {ir.. t aulhor".. I : l ~ lnamc: (Il) author index referenced to p;lrt

A. (C) r c f c r e l l C e ~ li ..led alphabelically hy

JOUrnal: (D ) references J i ~ l e d chronologically by year: and (6 ) an alphabcllcallr"l

of publications. Only aboul 20 percenl of

lhe: references h:l\'c Ihe word.. "\'olcanlC

Iremor" or related lerms m lhe: 1111e. lindoflcn slgnlrK:anl rnformallOfl I mcludc:d

only In a plot or figure of an arllClc ThI:

resuliis Ihal a compuleri7.cd search by

L.cywon.ls. for example. Ilo'OUld nllS" many

Imporlanl referenccs.

gl..IS ha w bccnl>ludying volcanic lrelllO(

to learn aboutlhc movemenl of magma

beneath volcanoes. Evcntually. the '>Iud)

of volcanic l remor may provide adcqualc

"",Hnmg of Immlnenl cruptions. The: bib-

hogrolphy was prepared as a Ilomm! lC:x>l

and a!,OIIl'Ce of mformation for research

e .... and others Interested III lhe: subj«1. Acornpklc sel of rcfcn::occ:s §OCh as Ihl'> I'>

needed dunng limes of \ 'Okanic lrcmor'\

10 help ('\OIlu;l1(' lhe: actlVlly and IhI: hLc

hhood of CruplKlRS.

ZIP

_ ACCT I

This is the: first eOfllprchcnslYC bIbliog

raphy 00 volcanIC tremor. it Iypc of seis

mic activily recorded al :.cllYe volcanoc:s.Recenlly_ selSmologl.'>lS and vokanolo-

(Individual Issues are $1.00 each)

EXPtR. DATE

o 2 yr. $20.00o 1 yr. $10.00

I,D, I

A BIIlUOORAI>I!Y OF VOLCANICTRI:.MOR AND RELATED !>IIENOM-

ENA Ily Stcphen R. McNutt. 1989.130 p. 510,00

TOTAl AMOUNT ENCLOSED:S -

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o RENEWAL: To receive your magazloe contrnuouSly. send In renewal 60 days beloreexpiralion date shown on your address label (Example. EXP9012meanslhatthe subscnplJon ellplres on recetpl of December 1990 issue.) Pleaseenclose address labellrom pas11SS08.

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california geology magazine april 1990

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