UNITED STATES DEPARTMENT OF THE INTERIOR
GEOLOG l CAL SURVEY
Geotechnical Framework Study o f S h e l i k o f S t r a i t , Alaska
b Y
Monty A. Harnpton
OPEN-F I LE REPORT
83 - 200
T h i s report i s p r e l i m i n a r y and has not been reviewed for conformity w i t h
Geological Survey e d i t o r i a l standards and s t r a t i g r a p h i c nomenclature. Any use
of trade names i s f o r d e s c r i p t i v e purposes only and does not imply endorsement
by the USGS.
INTRODUCTION
S t u d i e s have been conducted by t h e U.S. G e o l o g i c a l Survey t o ' i d e n t i f y
g e o l o g i c c o n d i t i o n s t h a t might impose c o n s t r a i n t s on o f f s h o r e i n d u s t r i a l
a c t i v i t i e s i n She l ikof S t r a i t , Alaska, an a r e a d e s i g n a t e d f o r pe t ro leum
l e a s i n g ( F i g . 1; Hampton and o t h e r s , 1981; Hampton and Winters , 1981) . A s
par t of t h e s e s t u d i e s sediment c o r e s were c o l l e c t e d th roughout the s t r a i t
( F i g . 2 ) , and p h y s i c a l p r o p e r t i e s of sed iment samples were measured by
l a b o r a t o r y q e o t e c h n i c a l t e s t i n g methods. The g e o t e c h n i c a l d a t a a r e p r e s e n t e d
i n t h i s r e p o r t and a r e e v a l u a t e d from a r e g i o n a l p e r s p e c t i v e t o i n f e r t h e
d e f o r m a t i o n a l r eponse of the sed imenta ry d e p o s i t s t o s t a t i c and dynamic l o a d s .
A p p l i c a t i o n of t h e t e s t d a t a t o a r e g i o n a l a n a l y s i s is r e s t r i c t e d by the
degree t o which c o r e samples a r e r e p r e s e n t a t i v e of t h e sed imenta ry d e p o s i t s .
I n t e r p r e t i v e g e o l o g i c s t u d i e s i n d i c a t e t h a t t he c o r e s used f o r g e o l o g i c
t e s t i n g cover t h e range of s u r f i c i a l sediment t y p e s in t h e She l ikof S t r a i t
l e a s e a r e a , b u t a n a l y s i s of s e i s m i c - r e f l e c t i o n p r o f i l e s r e v e a l s t h e e x i s t e n c e
of b u r i e d s t r a t i g r a p h i c u n i t s t h a t were n o t sampled because t h e y lie beneath
t h e maximum c o r e l e n g t h of 3 m ampto ton and o t h e r s , 1981; Hampton and Winters ,
1981) . There fo re , the c o n c l u s i o n s reached i n t h i s r e p o r t app ly d i r e c t l y t o
t h e upperlnost d e p o s i t s i n t h e s t r a t i g r a p h i c section, o n l y . Extrapolat ion
beyond t h e d e p t h s of sampl ing i s l i m i t e d by the v e r t i c a l u n i f o r m i t y of
sediment type .
GEOLOGIC SETTING
She l ikof S t r a i t i s a n e a r l y p a r a l l e l - s i d e d marine channe l s i t u a t e d
between t h e Kodiak I s l a n d group and t h e Alaska Pen insu la (Fig . 1). The s t r a i t
marks the l o c a t i o n of a n o r t h e a s t - t r e n d i n g i n n e r forearc b a s i n t h a t i s l o c a t e d
n e a r the c o n v e r g e n t margin of the North America p l a t e where it is b e i n g
u n d e r t h r u s t by t h e p a c i f i c p l a t e (von Huene, 1979) . Large e a r t h q u a k e s are
common t o t h e r e g i o n ; a t least 95 p t e n t i a l l y d e s t r u c t i v e e v e n t s (magni tude
>6) have o c c u r r e d s i n c e r e c o r d i n g began i n 1902. Twelve vo lcanoes have
e r u p t e d w i t h i n t h e l a s t 10,000 y e a r s a l o n g t h e Alaska P e n i n s u l a a d j a c e n t t o
t h e s t r a i t .
The s e a f l o o r of S h e l i k o f Strait c o n s i s t s of a g e n t l y s o u t h w e s t - s l o p i n g
c e n t r a l p l a t f o r m b o r d e r e d by narrow m a r g i n a l c h a n n e l s p a r a l l e l t o t h e Kodiak
i s l a n d s and t h e Alaska P e n i n s u l a (Fig. 3 ) . Sha l low s h e l v e s t r e n d a l o n g t h e
a d j a c e n t l andmasses , and t h e y a r e connec ted t o t h e m a r g i n a l c h a n n e l s by
s t e e p l y s l o p i n g s e a f l o o r . Water d e p t h i n t h e n o r t h e a s t p a r t of t h e s t r a i t i s
g e n e r a l l y less t h a n 200 rn, whereas i n t h e s o u t h w e s t it g e n e r a l l y e x c e e d s 200 m
and i s a s much as 300 m. Superimposed on t h e p l a t f o r m a r e some l o c a l h i g h s
and lows t h a t have as much a s 100 m r e l i e f . Along t h e axes of t h e m a r g i n a l
c h a n n e l s are s e v e r a l c l o s e d d e p r e s s i o n s on t h e o r d e r of 30 m r e l i e f .
Sed imen ta ry d e p o s i t s of presumed P l e i s t o c e n e and Holocene age o v e r l i e a n
i r r e g u l a r unconf o r m i t y above T e r t i a r y and o l d e r bedrock. Th ickness of t h e
s e d i m e n t above bed rock , measured from s e i s m i c - r e f l e c t i o n p r o f i l e s , i s a b o u t 80
t o 100 m i n t h e n o r t h e a s t h a l f of t h e s t r a i t and i n c r e a s e s a b r u p t l y t o more
t h a n 800 1n i n the s o u t h w e s t ( F i g . 4 ) . The t h i c k e n i n g r e f l e c t s a deepen ing of
t h e unconf o r m i t y .
Four s e i s m i c - s t r a t i g r a p h i c u n i t s can be d i s t i n g u i s h e d above bedrock ( k i g .
5 ) . The l o w e s t u n i t ( u n i t 1 i n F ig . 5 ) f i l l s t h e bedrock d e p r e s s i o n and
r e a c h e s a t h i c k n e s s of 800 m. T h i s unit i s i n t e r p r e t e d as b e i n g of g l a c i a l
and g l a c i o m a r i n e o r i g i n (Whitney and o t h e r s , 1980 a , b ) . The n e x t h i g h e s t
u n i l ( u n i t 2 i n P ig . 5 ) i s r e l a t i v e l y thin (<60 rn) and o c c u r s main ly i n t h e
c e n t r a l p a r t of t h e s t r a i t . Sediment of t h i s u n i t was d e p o s i t e d w i t h i n low
a r e a s on the upper surface of bedrock and t h e g l a c i a l unit, and it a p p a r e n t l y
was emplaced by marine p r o c e s s e s d u r i n y t h e Holocene s e a - l e v e l rise. The
t h i r d u n i t ( u n i t 3 i n Fig . 51, which covers e s s e n t i a l l y a l l of the s e a f l o o r i n
t h e c e n t r a l par t of t h e s t r a i t ( p l a t f o r m and marg ina l c h a n n e l s ) , is up t o 180
m t h i c k ( F i g . 6 ) and was d e p o s i t e d by t h e modern-day o c e a n i c c u r r e n t regime of
s o u t h w e s t e r l y b a r o c l i n i c f low from Cook I n l e t and t h e e a s t e r n Gulf of Alaska
(Muench and Schumacher, 1980). Uni t 4 i n F i g u r e 5 u n d e r l i e s t h e s h a l l o w
s h e l v e s and i n t e r f i n g e r s seaward with u n i t 3. It is composed of sediment
e roded from t h e a d j a c e n t landmasses. The cores s u b j e c t e d t o g e o t e c h n i c a l
t e s t i n g and d i s c u s s e d i n t h i s paper were t a k e n from u n i t 3.
METHODS
Sediment c o r e s were c o l l e c t e d a t 65 s t a t i o n s on two c r u i s e s i n She l ikof
S t r a i t , i n June 1980 aboard t h e USGS R/V S.P. LEE and i n J u l y and August 1981
aboard t h e NOAA s h i p DISCOVERER ( P i g . 2 ) . A g r a v i t y c o r i n g sys tem wi th 8.5-cm
d i a m e t e r p l a s t i c l i n e r s i n s t e e l c o r e b a r r e l s was used on t h e 1980 c r u i s e ,
whereas a v i b r a c o r i n g sys tem wi th a 10-cm s q u a r e c r o s s - s e c t i o n p l a s t i c l i n e r
i n t h i n - w a l l s t a i n l e s s s t e e l b a r r e l was employed on t h e 1981 c r u i s e . Sorne
grab samples were t aken a t l o c a t i o n s of c o a r s e sediment where the c o r i n g
d e v i c e s were i n e f f e c t i v e .
Two c o r e s were t aken a t most s t a t i o n s . One was d e s i g n a t e d mainly f o r
g e o l o g i c a l a n a l y s i s . It was c u t i n t o 1-m o r 1.5-m-long s e c t i o n s , then s p l i t
l e n g t h w i s e f o r g e o l o g i c a l d e s c r i p t i o n and vane-shear s t r e n g t h t e s t i n g .
Subsamples were t a k e n f o r index p r o p e r t y d e t e r m i n a t i o n s .
The second c o r e was t aken e x p r e s s l y f o r g e o t e c h n i c a l t e s t i n g . It was c u t
i n t o 1-m-long s e c t i o n s , wrapped i n c h e e s e c l o t h , covered w i t h m i c r o c r y s t a l l i n e
wax, and s t o r e d u p r i g h t i n a r e f r i g e r a t o r . These c o r e s were l a t e r s u b j e c t e d
t o a s u i t e of g e o t e c h n i c a l tests i n l a b o r a t o r i e s a t t h e U S G S and a t a
commercial t e s t i n g company.
S e v e r a l index p r o p e r t i e s were determined f o r subsamples of t h e sediment
c o r e s . Grain size was measured by s i e v i n g and p i p e t t i n g i n t o f o u r s i z e
c l a s s e s : gravel. 0 2 m m ) , sand (2-0.062 mm), s i l t (0.062-0.004 mrn) , and c l a y
((0.004 m m ) . Water c o n t e n t , a s a pe rcen tage of d r y sediment weight , was
de te rmined from t h e weight of sediment samples b e f o r e and a f t e r even d r y i n g a t
105OC. A c o r r e c t i o n f o r s a l t c o n t e n t of s e a water (3 .5%) w a s made t o t h e
weighing 's . A t t e r b e r g l i m i t s were determined a c c o r d i n g t o s t a n d a r d procedures
(American S o c i e t y f o r T e s t i n g and M a t e r i a l s , 19761, e x c e p t t h a t samples were
n o t s i e v e d p r i o r t o t e s t i n g . Carbon c o n t e n t was measured wi th a LECO carbon
d e t e r m i n a t o r w i t h i n d u c t i o n f u r n a c e and a c i d d i g e s t i o n . Vane s h e a r
d e t e r m i n a t i o n s of undrained s h e a r s t r e n g t h were made on s p l i t c o r e h a l v e s wi th
a motorized d e v i c e a t a vane r o t a t i o n r a t e of 90°/min. The vane is 1 /2 inch
diamete r by 1 /2 i n c h high and was i n s e r t e d i n t o t h e sediment t o a dep th twice
the h e i g h t of t h e vane.
C o n s o l i d a t i o n tests were run on subsamples from g e o t e c h n i c a l c o r e s t o
de te rmine sub- fa i l u r e de format iona l p r o p e r t i e s . Most t e s t s were run on an
oedometer i n a s t r e s s - c o n t r o l l e d mode (Lambe, 1951). Others w e r e run i n a
t r i a x i a l l o a d i n g c e l l under c o n s t a n t r a t e of s t r a i n c o n d i t i o n s (Wissa and
o t h e r s , 1971). The c o n s o l i d a t i o n tests measure change i n volume with change
i n a p p l i e d load. The r e s u l t s a r e normally p l o t t e d as void r a t i o ( e = volume
of voids/volume of s o l i d s ) ve rsus the l o g a r i t h m of e f f e c t i v e (buoyan t )
v e r t i c a l s t r e s s I ) . Two u s e f u l parameters a r e d e r i v e d from t h e s e curves :
the compression i n d e x and t h e maximum p a s t p r e s s u r e . The compression i n d e x
(C,) i s t h e s l o p e of t h e s t r a i g h t - l i n e p o r t i o n of the e- log p a curve and
i n d i c a t e s the amount of compression produced by a p a r t i c u l a r load increment .
I
The maximum p a s t p r e s s u r e ( u ) i s t h e g r e a t e s t e f f e c t i v e overburden s t r e s s t o Vm
which the sediment has e v e r been exposed and i s determined from t h e e-Log p '
curve by a s imple g r a p h i c a l c o n s t r u c t i o n (Casagrande, 1936) . The r a t i o
I I
of a t o t h e e f f e c t i v e overburden stress a t t h e t ime of sampling ( u ) i s t h e Vm vo
o v e r c o n s o l i d a t i o n r a t i o (OCR), which i s a measure of unloading t h a t t h e
sediment may have exper ienced , by e r o s i o n f o r example, A t h i r d parameter , the
c o e f f i c i e n t of c o n s o l i d a t i o n ( c v ) , i s determined f o r each load increment of
t h e one-dimensional c o n s o l i d a t i o n tes t and i s r e l a t e d t o t h e r a t e of
c o n s o l i d a t i o n .
S t a t i c t r a x i a l t e s t s were run on c y l i n d r i c a l samples 3.6-cm diamete r and
7.6-cm long i n o r d e r t o determine s t r e n g t h p r o p e r t i e s of t h e sediment . T e s t s
were run under undrained c o n d i t i o n s wi th pore p r e s s u r e measurements isho hop
and Henkel, 1964) . Most samples were c o n s o l i d a t e d i s o t r o p i c a l l y p r i o r t o
t e s t i n g , b u t some were c o n s o l i d a t e d a n i s o t r o p i c a l l y .
Dynamically loaded t r i a x i a l t e s t s were a l s o run, wi th t h e a x i a l s t r e s s on
samples v a r i e d s i n u s o i d a l l y a t 0.1 Hz. Both con~press ion and t e n s i o n were
a p p l i e d a t a predetermined percen tage of t h e s t a t i c s t r e n g t h . These t e s t s can
be used t o e v a l u a t e t h e f a i l u r e c o n d i t i o n s of sediment under repea ted load lng ,
such as by ea r thquakes .
A f i r s t set of t r i a x i a l t e s t s was run on sediment samples t h a t were
c o n s o l i d a t e d t o somewhat a r b i t r a r y s t r e s s l e v e l s . However, the later t e s t i n g
program fo l lowed t h e normalized st.ress parameter (NSP) approach (Ladd and
Foot t , 1974), whereby consol ida t ion s t r e s s e s a r e chosen on the b a s i s of
I
maximum p a s t p r e s su re ( o ) , a s determined from conso l ida t ion tests. vm
I
Typica l ly , t h e t r i a x i a l t e s t specimen was consol ida ted t o fou r t imes u Vm '
which e l imina t e s some of t he d i s turbance e f f e c t s a s soc i a t ed with cor ing .
~ v e r c o n s o l i d a t i o n w a s a r t i f i c i a l l y induced i n some tests by rebounding t h e
specimen t o lower s t r e s s l e v e l s before applying the t r i a x i a l load. Measured
values of undrained shear s t r e n g t h (SU) a r e normalized with respect t o
e f f e c t i v e overburden s t r e s s ( 0 ) . A premise of the NSP method i s t h a t the v
I
r a t i o S / a i s cons tan t f o r a p a r t i c u l a r value of oCR. Moreover, a r e l a t i o n u v
e x i s t s between s /uv1 and W R t h a t allows p r e d i c t i o n of sediment s t r e n g t h a t u
depths below the l e v e l of sampling (Mayne, 1980).
RESULTS
Sediment d e s c r i p t i o n , index p rope r t i e s : Sediment samples could only be
c o l l e c t e d t o shal low depths ( c 3 m) beneath t h e s e a f l o o r . Therefore, most a r e
from t h e highest s t r a t i g r a p h i c u n i t ( u n i t 3, Fig . 5 ) . However, judging from
se i smic - r e f l ec t i on p r o f i l e s over sampling s t a t i o n s , a few outcrops of o t h e r
u n i t s were a l s o sampled. Se ismic- re f lec t ion p r o f i l e s a l s o show t h a t u n i t 3
has a t y p i c a l th ickness of about 80 t o 100 m ( ~ i g . 6). The appearance of
a c o u s t i c ref l e c t o r s wi th in t h i s u n i t i n d i c a t e s some l i t h o l o g i c v a r i a b i l i t y
with depth, b u t t h e r e i s no reason t o suspec t r a d i c a l changes i n sediment
type, except f o r pos s ib l e t h i n beds of volcanic ash. The phys i ca l p r o p e r t i e s
for t he cores should t he re fo re be r ep re sen t a t i ve of t he t e r r i genous component
of the u n i t a s a whole, but d r i l l - h o l e samples would be necessary t o confirm
t h i s .
The t e x t u r e of s u r f i c i a l sediment on the c e n t r a l p l a t f o r m and i n t h e
a d j a c e n t marginal channe l s g r a d e s from g r a v e l l y and sandy m a t e r i a l i n t h e
n o r t h e a s t p a r t of the s t rai t t o mud i n the sou thwes t (~igs. 7 and 8; Appendix
A ) . A g e n e r a l f i n i n g t r e n d from nor thwes t t o s o u t h e a s t a c r o s s t h e p l a t f o r m
a l s o e x i s t s .
The two g r a b samples of c o a r s e sediment r ecovered from Stevenson Entrance
appear t o have been t a k e n from o u t c r o p s of u n i t 1. Most of t h e c o a r s e c l a s t s ,
which range t o bou lde r s i z e , a r e a n g u l a r t o subangu la r , and some a r e f a c e t e d .
This s u p p o r t s t h e h y p o t h e s i s t h a t u n i t 1 was d e p o s i t e d by g l a c i a l p r o c e s s e s .
A few g r a b samples of c o a r s e m a t e r i a l were also recovered from the
sha l low s h e l v e s and from t h e a d j a c e n t s lopes. They probably are from u n i t
4. Coarse c l a s t s have s i m i l a r morphology t o t h o s e from u n i t 1, perhaps
r e f l e c t i n g g l a c i a l t r a n s p o r t a t some p o i n t i n t h e i r h i s t o r y .
Sediment c o r e s from t h e p l a t f o r m and marg ina l channe l s i n t h e c e n t r a l
p o r t i o n of t h e s t r a i t have a f a i r l y uniform s t r a t i g r a p h y wi th dep th . Sandy
sed iment i n t h e n o r t h e a s t end of t h e s t r a i t i s predominant ly g reen i sh -gray ,
wi th v a r i a t i o n s from black t o ye l lowish brown. S a n d - f i l l e d burrows, pebb le
c l a s t s , and whole o r broken s h e l l s a r e common. I n p r o g r e s s i v e l y f i n e r - g r a i n e d
c o r e s t o the sou thwes t , c o l o r remains g reen i sh -gray b u t i s l e s s v a r i e d , and
s h e l l s and c l a s t s a r e r a r e .
A l a y e r of v o l c a n i c a s h occurs i n many c o r e s . Maximum t h i c k n e s s of t h e
l a y e r i s n e a r l y 20 cm. It i s s ize -g raded , w i t h t h e c o a r s e s t b a s a l f ragments a
few m i l l i m e t e r s d iamete r . The c o l o r i s from t a n t o whi te wi th a pink cast.
The r e f r a c t i v e i n d e x of t he ash i s 1.485 + 0.002, which i n t h i s r eg ion i s
unique t o the o u t f a l l from the 1 9 1 2 Katmai e r u p t i o n (Nayudu, 1964; P r a t t and
o t h e r s , 1973) . Depth of t h e ash beneath the s e a f l o o r waq used t o c a l c u l a t e
v a l u e s of post-1912 sediment accumulat ion r a t e ( F i g . 9 ) . Accumulation r a t e
v a r i e s s i g n i f i c a n t l y th roughout t h e s t r a i t . It is g r e a t e s t n e a r t h e Alaska
P e n i n s u l a a t t h e southwest end of t h e s t r a i t , whereas it i s n e a r z e r o a t
p l a c e s i n t h e marginal channe l a l o n g t h e Kodiak i s l a n d group.
Water c o n t e n t o f sediment is shown i n F igure 10 a s i n t e r p o l a t e d v a l u e s a t
1-m dep th i n c o r e s . It is c a l c u l a t e d a s a p e r c e n t a g e of dry sediment weight ,
and t h e r e f o r e , v a l u e s i n excess of 100% a r e p o s s i ~ l e i f t h e weight of wa te r
exceeds t h e weight of sediment g r a i n s . Water c o n t e n t g e n e r a l l y d e c r e a s e s t o
t h e n o r t h e a s t , i n v e r s e l y c o r r e l a t i n g wi th g r a i n s i z e . Moreover, wa te r c o n t e n t
i n c r e a s e s a c r o s s t h e s t r a i t , from t h e Alaska p e n i n s u l a t o Kodiak I s l a n d . Bulk
sediment d e n s i t y a t 1 - m dep th , which is c a l c u l a t e d from water c o n t e n t and
g r a i n spec i f ic g r a v i t y , co r respond ing ly d e c r e a s e s down and a c r o s s the s t r a i t
( F i g . 11). Average g r a i n s p e c i f i c g r a v i t y i t s e l f shows no d i s c e r n i b l e t r e n d
( ~ i g . 12).
A t t e r b e r g l i m i t s d e s c r i b e t h e p l a s t i c i t y of sed iment , i n t e r n s of the
l i q u i d limit (wa te r content t h a t s e p a r a t e s p l a s t i c and l i q u i d b e h a v i o r ) and
t h e p l a s t i c l i m i t (wa te r c o n t e n t t h a t s e p a r a t e s semi - so l id and p l a s t i c
b e h a v i o r ) . Useful d e r i v a t i v e s a r e t h e p l a s t i c i t y i n d e x ( d i f f e r e n c e between
t h e l i q u i d and p l a s t i c l i m i t s ) , and t h e l i q u i d i t y i n d e x ( p o s i t i o n of tne
n a t u r a l wa te r c o n t e n t r e l a t i v e t o t h e l i q u i d and p l a s t i c l i m i t s ) . C e r t a i n
t r e n d s i n p l a s t i c i t y are e v i d e n t i n She l ikof S t r a i t . Average l i q u i d l i m i t ,
p l a s t i c l i m i t , and p l a s t i c i t y i n d e x i n c r e a s e down t h e s t r a i t toward t h e
sou thwes t , and a l s o g e n e r a l l y across the s t r a i t , toward t h e s o u t h e a s t ( F i g s .
13, 14, and 15; Appendix A ) . These p r o p e r t i e s also g e n e r a l l y i n c r e a s e wi th
d e c r e a s e i n mean g r a i n s i z e ( F i g s . 16, 1 7 , and 181, a l though t h e d a t a fo r
p l a s t i c l i m i t are q u i t e s c a t t e r e d . P l a s t i c l i m i t i s l e s s v a r i a b l e t h a n l i q u i d
l i m i t , which i s t y p i c a l l y t h e c a s e ( M i t c h e l l , 1976; R ichards , 1962) .
C o r r e l a t i o n s have been made between l i q u i d l i m i t and c o m p r e s s i b i l i t y
(Herrmann and o t h e r s , 1972; Skempton, 1 9 4 4 ) . The m a j o r i t y of She l ikof S t r a i t
samples f a l l w i t h i n t h e medium (30 < l i q u i d l i m i t < 5 0 ) and h igh ( l i q u i d l i m i t
>50) c o m p r e s s i b i l i t y ranges .
Near ly a l l measured l i q u i d i t y i n d i c e s i n She l ikof S t r a i t a r e g r e a t e r than
1 (Appendix A ) , which i s u s u a l f o r n e a r - s e a f l o o r marine sediment . Sediment
w i t h a l i q u i d i t y i n d e x g r e a t e r than one behaves as a l i q u i d when remolded.
A p l o t of L i q u i d i t y i n d e x ve r sus p l a s t i c i t y i n d e x - termed a p l a s t i c i t y
c h a r t (Casagrande, 1948) - shows a t r e n d p a r a l l e l t o t h e A-line t h a t d i v i d e s
b a s i c s o i l t y p e s (F ig . 1 9 ) . Most sediment samples from She l ikof S t r a i t p l o t
below t h e A-line, which i s t y p i c a l of i n o r g a n i c s i l t and s i l t y c l a y of h igh
c o m p r e s s i b i l i t y . The l i n e a r t r e n d of d a t a p o i n t s i s expec ted for samples
t a k e n th roughout t h e same sed imenta ry d e p o s i t ( ~ e r z a g h i , 1955; R ichards ,
1962) .
Undrained s h e a r s t r e n g t h of sediment samples (SU), a s measured wi th a
l a b o r a t o r y m i n i a t u r e vane s h e a r d e v i c e , g e n e r a l l y d e c r e a s e s toward t h e
sou thwes t end of t h e s t r a i t , and t h u s c o r r e l a t e s w i t h t h e wa te r c o n t e n t t r e n d ,
a l though t h e r e is much s c a t t e r ( F i g s . 20 and 21; Appendix A ) . The c o n s i s t e n c y
of most of t h e n e a r - s e a f l o o r sediment can be c l a s s i f i e d as very soft (SU < 1 2
k i l o p a s c a l s ) , h u t some is s o f t (12 kPa < Su < 24 kPa) t o medium ( 2 4 kPa < Su <
48 kPa) (Terzagh i and Peck , 1948). Harnpton and o t h e r s (1981) showed t h a t
s h e a r s t r e n g t h i s a n i s o t r o p i c i n She l ikof S t r a i t sediment c o r e s . Values of
s h e a r s t r e n g t h measured with the a x i s of vane r o t a t i o n p e r p e n d i c u l a r t o t h e
a x i s of c o r e samples exceed t h e va lues of s t r e n g t h measured wi th t h e a x i s o f
vane r o t a t i o n p a r a l l e l t o the c o r e a x i s . The magnitude of sediment s t r e n g t h
t h e r e b y depends on t h e o r i e n t a t i o n of t h e a p p l i e d s t r e s s .
Sediment samples from She l ikof S t r a i t are c h a r a c t e r i z e d by low t o
i n t e r m e d i a t e c o n t e n t of o r g a n i c carbon, compared t o o t h e r marine a r e a s
( ~ o r d o v s k i y , 1965, 1969; Gardner and o t h e r s , 1980; L i s i t z i n , 1972; Rashid and
Brown, 1975) . Most va lues a r e between 0.40% and 1.50%. Organic carbon
g e n e r a l l y i n c r e a s e s down t h e s t r a i t toward the sou thwes t , as w e l l as a c r o s s
t h e s t r a i t toward t h e s o u t h e a s t (F ig . 2 2 ; Appendix A ) . C o r r e l a t i o n s with
o t h e r p h y s i c a l p r o p e r t i e s were shown by Hampton and o t h e r s (1981) . Organic
carbon c o n t e n t c o r r e l a t e s p o s i t i v e l y wi th water c o n t e n t and p l a s t i c i t y index ,
whereas an i n v e r s e c o r r e l a t i o n i s found wi th g r a i n s i z e and vane s h e a r
s t r e n g t h . C o r r e l a t i o n s s i m i l a r t o those d e s c r i b e d above have been r e p o r t e d by
o t h e r s f o r low organic-carbon c o n t e n t sediment (Bordovskiy, 1965, 1969; Bush
and K e l l e r , 1981; K e l l e r and o t h e r s , 1979; L i s i t z i n , 1972; M i t c h e l l , 1976;
Ode11 and o t h e r s , 1960) .
P e r c e n t ca lc ium carbona te i s t y p i c a l l y low i n She l ikof S t r a i t sediment
( F i g . 23; Appendix A ) . Most va lues a r e less than 3.50%. Two l o c a t i o n s wi th
anomalously high va lues , off Shuyak I s l a n d and i n Stevenson Entrance, a r e near
t h e boundary of t h e s t r a i t .
C o n s o l i d a t i o n p r o p e r t i e s : Conso l ida t ion p r o p e r t i e s a s determined f r o m
l a b o r a t o r y tests a r e l i s t e d i n Table 1. A l l t e s t s i n d i c a t e a maximum p a s t
I I
p r e s s u r e ( a ) g r e a t e r t h a n t h e p r e s e n t overburden p r e s s u r e ( a ) . 'I'h e vm VO
I I
r a t i o am/Ovo is t h e o v e r c o n s o l i d a t i o n r a t i o n (OCR) and i s g r e a t e r than 1 .0
f o r a l l t e s t s . The u s u a l i m p l i c a t i o n i s t h a t t h e sediment has exper ienced
un load ing a s a consequence of e r o s i o n . However, t h e r e i s no g e o l o g i c a l
ev idence f o r e r o s i o n ; i n f a c t , sediment i s accumulat ing a t h igh rates
throughout most of t h e s t r a i t (F ig . 9). The high va lues of OCR probably
r e p r e s e n t i n i t i a l c e m e n t a t i o n of s e d i m e n t p a r t i c l e s o r g r a i n i n t e r l o c k i n g and
are n o t i n d i c a t i v e of o v e r c o n s o l i d a t i o n i n t h e s t r i c t s e n s e of t h e term.
Compression i n d e x (Cc) i s a measure of the amount of c o n s o l i d a t i o n t h a t
o c c u r s f o r a g i v e n i n c r e m e n t i n l o a d . The c o a r s e s e d i m e n t a t t h e n o r t h e a s t
end o f t h e s t r a i t i s less c o m p r e s s i b l e t h a n the p r o g r e s s i v e l y f i n e r s ed imen t
t o t h e s o u t h w e s t , as i n d i c a t e d by a s o u t h w e s t t r e n d of i n c r e a s i n g Cc ('L'able
1). R i c h a r d s (1962) r e p o r t e d a r ange of 0.20 t o 0.87 f o r Cc measured on
samples of mar ine s e d i m e n t from many a r e a s , and r ~ ~ o s t v a l u e s from S h e l i k o f
S t r a i t f a l l w i t h i n this range.
Compress ion i n d e x commonly shows a l i n e a r r e l a t i o n t o l i q u i d l i m i t
(LL). The d a t a f rom S h e l i k o f S t r a i t , when p l o t t e d i n t h i s manner, e x h i b i t a
g e n e r a l t r e n d , n u t w i t h much s c a t t e r ( F i g . 2 4 ) . Skempton (1944) found t h a t
t h e r e l a t i o n can be e x p r e s s e d as
cc = 0.009 (LL - l o ) ,
and t h e r e g r e s s i o n e q u a t i o n f o r S h e l i k o f S t r a i t s e d i m e n t i s s i m i l a r :
C, = 0.006 (LL + 5.7).
The r a t e a t which c o n s o l i d a t i o n o c c u r s i n r e s p o n s e t o l o a d i n g d e t e r m i n e s
t h e c o e f f i c i e n t of c o n s o l i d a t i o n ( c v ) . I t i s d i r e c t l y r e l a t e d t o p e r m e a b i l i t y
of a s e d i m e n t and i n v e r s e l y r e l a t e d t o t h e c o m p r e s s i b i l i t y . The c o e f f i c i e n t
i s c a l c u l a t e d f o r e a c h l o a d i n c r e m e n t d u r i n g a l a b o r a t o r y c o n s o l i d a t i o n test
from p l o t s of d e f o r m a t i o n v e r s u s t i n e . As shown i n Tab le 1, c, c~mmonly
v a r i e s t h rough one t o two o r d e r s of magni tude f o r a s i n g l e tes t . No g e n e r a l
t r e n d i n t h e d a t a i s e v i d e n t , a l t h o u g h t h e h i g h e x p e c t e d p e r m e a b i l i t y and low
c o m p r e s s i b i l i t y of c o a r s e - g r a i n e d s e d i m e n t would s u g g e s t a d e c r e a s e of c v to
t h e s o u t h w e s t , Measurements of cv f o r c l a y s e d i m e n t f rom v a r i o u s mar ine
l o c a t i o n s by R i c h a r d s and Hamilton (1967) a r e i n t h e r a n g e 3.2 - 6.0 x cm
2/sec, which are lower t h a n t y p i c a l v a l u e s i n SheLikof S t r a i t .
S t a t i c s t r e n g t h p r o p e r t i e s : Sediment p r o p e r t i e s derived from s t a t i c t r i a x i a l
s t r e n g t h tests a r e l i s t e d i n Table 2 . ?'he primary measured p r o p e r t y is t h e
undrained s h e a r s t r e n g t h (SU). ~t is t h e maximum s u s t a i n a b l e s h e a r s t r e s s
1
w i t h i n a sample s u b j e c t e d t o a p a r t i c u l a r c o n s o l i d a t i o n s t r e s s (ac) . SU a c t s
a long a p l a n i n c l i n e d a t 45O t o t h e a x i a l load . The a r e s i n e of S, d i v i d e d by
t h e e f f e c t i v e normal s t r e s s a c r o s s t h i s p lane i s t h e e f f e c t i v e ang le of
i n t e r n a l f r i c t i o n ( ) whose magnitude i s an i n d i c a t i o n of t h e s t r e n g t h
behav ior of the sediment under slow ( d r a i n e d ) l o a d i n g c o n d i t i o n s . In
I
comparison, t h e r a t i o S / O g i v e s an i n d i c a t i o n of t h e s t r e n g t h behav ior U C
d u r i n g r a p i d ( u n d r a i n e d ) load ing c o n d i t i o n s . The d i f f e r e n c e i n d ra ined and
undrained s t r e n g t h behavior depends on t h e p o r e wa te r p r e s s u r e genera ted i n
response t o t h e tendency f o r volume change when t h e sediment is a x i a l l y
loaded. If a sediment has a high tendency f o r volume change, t h e d i f f e r e n c e
i n s t r e n g t h between r a p i d and slow load ing can be s u b s t a n t i a l .
The e f f e c t i v e a n g l e of i n t e r n a l f r i c t i o n f o r t h e normally c o n s o l i d a t e d
sediment samples (OCR = 1) i n t h i s s t u d y i s r e l a t i v e l y high (35' - 46" ) .
Compare w i t h va lues given by Lambe and Whitman 1969, p. 149 and 306). The
h i g h e r v a l u e s ( > 40°) a r e i n t h e f i n e r sediment c o r e s from t h e southwest h a l f
of t h e s t r a i t able 2 ) . There fore , sediment from She l ikof S t r a i t appears t o
be a t y p i c a l l y s t r o n g under c o n d i t i o n s of d r a i n e d l o a d i n g , with the f i n e r
sediment e x h i b i t i n g h i g h e r s t r e n g t h . Samples t e s t e d a t OCR > 1 tend t o have
$' comparable t o t h a t of normally c o n s o l i d a t e d samples, e x c e p t f o r s t a t i o n 649
where some o v e r c o n s o l i d a t e d samples have s i g n i f i c a n t l y h i g h e r values. The
d a t a i n d i c a t e s i m i l a r d r a i n e d behavior of normal ly c o n s o l i d a t e d and
o v e r c o n s o l i d a t e d sediment i n t h e s t r a i t .
Lambe and Whitman (1969, p. 307, Fig . 21.4) d e t e c t e d a r e l a t i o n between
4' and p l a s t i c i t y index f o r normally c o n s o l i d a t e d s o i l . T r i a x i a l d a t a f o r
which t h e r e a r e p l a s t i c i t y index va lues i n She l ikof S t r a i t p l o t w i t h i n t h e
range of Lambe and Whitman's d a t a , e x c e p t f o r t h e c o r e a t s t a t i o n 511, which
i s abnormally s t r o n g f o r sediment wi th such high p l a s t i c i t y ( ~ i g . 25) .
Eva lua t ion of undrained s t r e n g t h , i n terms of S / a , r e q u i r e s some U C
judgement i n o r d e r t o d e t e c t t r e n d s . I n p a r t i c u l a r , t n e tests run a t law
I I
c o n s o l i d a t i o n s t r e s s ( a 1 seem t o g ive e r r a t i c va lues of S / a . This was C U C
a l s o shown t o be t h e c a s e f o r t r i a x i a l d a t a from nearby Kodiak Shelf wh amp ton,
i n p r e s s ) . T e s t s run a t high va lues of c o n s o l i d a t i o n stress (which c o r r e c t s
I
some of t h e e f f e c t s of d i s t u r b a n c e ) and OCR = 1 have v a l u e s of S / a between U C
1
0.3 and 0.6, with no a r e a l t r e n d able 2 ) . The va lue of s / u i n c r e a s e s wi tn u C
OCR f o r each c o r e t e s t e d .
The s t a t i c t r i a x i a l t e s t d a t a a r e p l o t t e d a c c o r d i n g t o t h e NSP approacn
i n F igure 26. The s l o p e ( A ) of t h e l i n e f o r each c o r e i s a measure of t h e
change i n undrained s t r e n g t h wi th OCR. Most c o r e s have A va lues between 0.79
and 0.97. Mayne (1980) compiled t h e r e s u l t s of many t r i a x i a l tests and found
a mean va lue of A = 0.64 wi th a s t a n d a r d d e v i a t i o n of 0.18. The sediment i n
She l ikof S t r a i t , wi th i ts r e l a t i v e l y high va lues of A, would t e n d t o r e t a i n
more of i t s s t r e n g t h a f t e r unloading compared t o most sediment examined by
Mayne (1980) . The A = 1.43 c a l c u l a t e d f o r t h e sediment of s t a t i o n 5 2 8 i s
g r e a t e r than t h e t h e o r e t i c a l l i m i t of = 1.0 , and f u r t h e r t e s t i n g i s r e q u i r e d
t o r e s o l v e t h i s c o n f l i c t .
Dynamic s t r e n g t h p r o p e r t i e s : The d a t a from t r i a x i a l s t r e n g t h t e s t s a r e given
i n Table 3. The q u a n t i t y rCy,/Su is t h e c y c l i c s t r e s s l e v e l , t h e average
v a l u e of s h e a r stress ( T ~ ~ ~ ) a p p l i e d s i n u s o i d a l l y w i t h f u l l stress r e v e r s a l a t
0.1 Hz, e x p r e s s e d as a p e r c e n t a g e of t h e s t a t i c u n d r a i n e d s h e a r s t r e n g t h
(SU). Pore w a t e r p r e s s u r e and s t r a i n accumula t e w i t h r e p e a t e d a p p l i c a t i o n of
T~ y c A t some p o i n t , t h e p o r e w a t e r p r e s s u r e a p p r o a c h e s t h e c o n f i n i n g stress,
s t r a i n i n c r e a s e s a b r u p t l y , and t h e s e d i m e n t f a i l s . I n o u r tests, f a i l u r e was
chosen when 20% s t r a i n was r eached .
Samples t y p i c a l l y fail i n f ewer c y c l e s a t p r o g r e s s i v e l y h i g h e r s t r e s s
l e v e l s . F i g u r e 27 shows t n e number of c y c l e s t o f a i l u r e v e r s u s s t r e s s Level
f o r S h e l i k o f S t r a i t samples . Although t h e r e i s some scat ter , the d a t a f a l l
w i t h i n t h e r a n g e of t e s t r e s u l t s on t e r r i g e n o u s s e d i m e n t from o t h e r a r e a s (Lee
and others, 1981; Anderson and o t h e r s , 1980; Hampton, i n p r e s s ) . Moderate
c y c l i c s t r e n g t h d e g r e d a t i o n is i n d i c a t e d ; t h a t i s , a f t e r 1 0 c y c l e s of l o a d i n g
( a s migh t be i m p a r t e d by a n e a r t h q u a k e , f o r e x a m p l e ) , t h e samples f a i l a t
stress l e v e l s between 60% and 80% of t h e i r s t a t i c s t r e n g t h .
DISCUSSION
The p r i m a r y g e o t e c h n i c a l c o n c e r n s i n S h e l i k o f S t r a i t i n c l u d e s e t t l e m e n t
of s t r u c t u r e s , h e a r i n g c a p a c i t y unde r s t a t i c and c y c l i c l o a d i n g l a t e r a l l o a d
c a p a c i t y , and anchor b r e a k o u t r e s i s t a n c e . N a t u r a l s l o p e f a i l u r e s a r e n o t a
s e r i o u s problem because o n l y one small s e d i m e n t s l i d e has been documented
(Hampton and o t h e r s , 1981 1. There i s some e v i d e n c e f o r gas -charged sediment,
b u t t h e problem of l o w s t r e n g t h t h a t might e x i s t i n s e d i m e n t of t h l s t y p e was
n o t a d d r e s s e d i n t h e p r e s e n t s t u d y .
m a t e r n a r y s e d i m e n t i n S h e l i k o f S t r a i t c o v e r s bedrock t o a t h i c k n e s s of
from 20 m t o more t h a n 800 m ( F i g . 4 ) . The sequence c o n s i s t s of P l e i s t o c e n e
g l a c i d l and g l a c i o m a r i n e s e d i m e n t a t t h e b a s e , o v e r l a i n by Holocene mar ine
d e p o s i t s . The h i g h e s t s t r a t i g r a p h i c u n i t , d e p o s i t e d by o c e a n i c c u r r e n t s a s
e x i s t today , has accumulated t o a t h i c k n e s s of 80-100 rn over most of t h e
s t r a i t ; the t o t a l range is abou t 20 m t o 180 m. Geo techn ica l t e s t i n g was
performed on ly on samples from t h i s uppermost u n i t . A g e o t e c h n i c a l a n a l y s i s
based on t h e s e d a t a p robab ly a d d r e s s e s most s i t u a t i o n s of e n g i n e e r i n g
concern . Deeper s t r a t i g r a p h i c u n i t s appear from i n t e r p r e t i v e g e o l o g i c s t u d i e s
t o be r e l a t i v e l y coarse -g ra ined ampto ton and Win te r s , 1981; Whitney and
o t h e r s , 198Oa, b ) , and they probably a r e s t a b l e , b u t deep d r i l l - c o r e samples
would have t o be o b t a i n e d i n o r d e r t o conf i rm t h i s by g e o t e c h n i c a l t e s t i n g .
The p a t t e r n of g r a i n - s i z e v a r i a t i o n ( F i g s . 7 and 8 ) e v i d e n t l y r e f l e c t s
p r o g r e s s i v e s o r t i n g by t h e s o u t h w e s t e r l y f lowing b a r o t r o p i c c u r r e n t t h a t
dominates c i r c u l a t i o n i n t h e s t r a i t . The p r e s e n t s t u d y and t h e p r e v i o u s
r e p o r t by Hampton and o t h e r s (1981) show t h a t some i n d e x p r o p e r t i e s vary i n
r e l a t i o n t o g r a i n s i z e . P r o p e r t i e s t h a t show a d i r e c t c o r r e l a t i o n and
t h e r e f o r e i n c r e a s e t o t h e sou thwes t down t h e s t r a i t and t o t h e s o u t h e a s t
a c r o s s t h e s t r a i t i n c l u d e wa te r c o n t e n t , l i q u i d l i m i t , p l a s t i c L i m i t ,
p l a s t i c i t y index , and o r g a n i c carbon c o n t e n t ( F i g s . 10 , 13, 14 , 15, and 2 2 ) .
P r o p e r t i e s t h a t c o r r e l a t e i n v e r s e l y wi th g r a i n s i z e i n c l u d e bulk sed iment
d e n s i t y and undrained ( v a n e ) s h e a r s t r e n g t h ( F i g s . 11 and 2 0 ) .
C o n s o l i d a t i o n t e s t s i n d i c a t e t h a t sediment samples a r e o v e r c o n s o l i d a t e d ,
b u t t h i s p robab ly i s a n e a r - s e a f l o o r d i a g e n e t i c o r f a b r i c phenonenon r a t h e r
than a r e s u l t of e r o s i o n , because n e t sediment accumula t ion i s p r e s e n t l y
o c c u r r i n g th roughout t h e s t r a i t (Tab le 1, Fig . 9 ) . The f i n e - g r a i n e d sediment
t o t h e sou thwes t nas h igh va lues of compression i n d e x (C',), which i n d i c a t e s
t h a t it i s more compress ib le t h a n the c o a r s e r m a t e r i a l t o the n o r t h e a s t . The
r a t e of c o n s o l i d a t i o n , a s shown by t h e c o e f f i c i e n t of c o n s o l i d a t i o n ( c V ) l is
h i g h l y v a r i a b l e f o r each c o n s o l i d a t i o n t e s t and does n o t show an a r e a l t r e n d
(Tab le 1). I n t u i t i v e l y , a h i g h e r va lue of c, would be expec ted f o r t h e
c o a r s e r - g r a i n e d sediment because of i t s normal ly h i g h e r p e r m e a b i l i t y and lower
c o m p r e s s i b i l i t y , b u t a p p a r e n t l y t h i s i s n o t t h e case .
Another unexpected r e s u l t i s t h a t t h e s t a t i c d r a i n e d s t r e n g t h , i n terrns
of t h e e f f e c t i v e a n g l e of i n t e r n a l f r i c t i o n , i s h i g h e r f o r t h e f i n e -
g r a i n e d sediment t h a n i t i s f o r t o t h e c o a r s e r - g r a i n e d samples (Table 2 ) .
u r a i n e d s t r e n g t h does n o t vary a p p r e c i a b l y w i t h OCR. Undrained s t a t i c
s t r e n g t h behav io r does no t e x h i b i t s i g n i f i c a n t a r e a l v a r i a t i o n . Values
I
of SU/oc f o r t e s t s run a t OCR = 1 a r e between 0 . 3 and 0.6. This pa ramete r
i n c r e a s e s w i t h OCR f o r each c o r e t h a t was t e s t e d . The NSP p r e - p r e s s u r e
pa ramete r ( A ) v a r i e s from 0.79 t o 0.97, which i n d i c a t e s s i g n i f i c a n t s t a t i c
s t r e n g t h i n c r e a s e w i t n OCR ( ~ i g . 26) . Again, no a r e a l t r e n d i s apparent.
But, because few d a t a p o i n t s were used t o plot t h e l i n e s i n F igure 26 and
because l a r g e s c a t t e r of data e x i s t s f o r some i n d i v i d u a l c o r e s , a d d i t i o n a l
s t r e n g t h t e s t i n g a t more l e v e l s of OCR would add p r e c i s i o n t o t h e p l o t s and
pe rhaps r e v e a l some s y s t e m a t i c v a r i a t i o n .
T e s t d a t a for most cores d e f i n e s i m i l a r r e sponse t o c y c l i c l o a d i n g over a
broad range of number of c y c l e s r e q u i r e d t o cause f a i l u r e ( e .q . , c o r e s 511,
525, 528, and 540 i n Fig . 271. bynamic s t r e n g t h d e g r e d a t i o n v a r i e s over a
L i m i t e d range a t low number of c y c l e s ; f o r i n s t a n c e , i t i s between abou t 60%
and 80% f o r 1 0 c y c l e s .
G e o t e c h n i c a l p r o p e r t i e s of She l ikof S t r a i t sed iment can be compared wi th
data from o t h e r s t u d i e s t o de te rmine i f t h e sediment h a s normal d e f o r m a t i o n a l
behav io r . However, few d a t a e x i s t f o r some p r o p e r t i e s , which makes the
e v a l u a t i o n s t e n t a t i v e .
Most v a l u e s of compression i n d e x f a l l w i t h i n t h e range of 0.20 t o 0.87
r e p o r t e d by Richards and Hamilton (1962) fo r s i l t y c l a y t o h i g h l y c o l l o i d a l
clay; one test on t h e c o r e from s t a t i o n 507 has a h igh va lue of 0.94 (Table
1). Skempton's (1944) c l a s s i f i c a t i o n of c o m p r e s s i b i l i t y based on l i q u i d l i m i t
i n d i c a t e s t h a t She l ikof S t r a i t samples a r e moderate ly t o h i g h l y compress ible
(Appendix A ) . S u b s t i t u t i o n of t h e c lass-boundary va lues of l i q u i d l i m i t
(moderate c o m p r e s s i b i l i t y : 30 < LL < 50; high c o m p r e s s i b i l i t y : LL > 50) i n t o
t h e r e g r e s s i o n e q u a t i o n f o r She l ikof S t r a i t d a t a (F ig . 2 4 ) ,
c c - 0.006 (LL + 5 . 7 ) ,
i n d i c a t e s t h a t t h e range of moderate c o m p r e s s i b i l i t y i s 0.21 < Cc < 0-33 and
t h e h igh range i s Cc < 0.33, which i s c o n s i s t e n t wi th c l a s s i f y i n g t h e sediment
a s moderate ly t o h i g h l y compress ible able 1).
E f f e c t i v e f r i c t i o n a n g l e ( 4 ' ) f o r sediment i n Shel ikof S t r a i t i s high
( 3 5 O - 46O) compared t o t h e range (20° - 40°) r e p o r t e d by Lambe and Whitman
(1969, p. 149 and 306) f o r normally c o n s o l i d a t e d sediment . Apparent ly , no
compi la t ions of ' e x c l u s i v e l y f o r t e r r i g e n o u s marine sediment have been
made. Hampton ( i n p r e s s ) r e p o r t s ' most ly i n t h e 30° - 40° range f o r
t e r r i g e n o u s samples from t h e Kodiak S h e l f . She l ikof S t r a i t t e r r i g e n o u s
sediment is r e l a t i v e l y s t r o n g under d r a i n e d l o a d i n g c o n d i t i o n s .
Lambe and whitman (1969, p. 452, Fig . 29.19) p r e s e n t d a t a on t h e
undrained s t r e n g t h o f normally c o n s o l i d a t e d marine c l a y , and va lues
1
of s / o a r e between about 0.2 and 0.4. The range f o r normal ly c o n s o l i d a t e d u C
She l ikof S t r a i t samples i s 0.3 t o 0.6, s o t h e y are r e l a t i v e l y s t r o n g under
c o n d i t i o n s of undrained load ing . S / cr ' f o r normal ly c o n s o l i d a t e d t e r r i g e n o u s U C
sediment from the Kodiak She l f a r e a l s o h igh , from 0.4 t o 1 .0 (Hampton, i n
p r e s s 1.
Values of t h e NSP f a c t o r A are h igh (0.79 - 0.97) compared t o the average
va lue of 0.64 ( s t a n d a r d d e v i a t i o n = 0.18) i n t h e e x t e n s i v e compi la t ion by
Mayne (1980). The i m p l i c a t i o n i s t h a t t h e i n c r e a s e of s t r e n g t h wi th
o v e r c o n s o l i d a t i o n i s h i g h e r than normal.
The low t o moderate c y c l i c s t r e n g t h d e g r e d a t i o n of She l ikof S t r a i t
samples is s i m i l a r t o t h e behav io r of c l a y sediment r e p o r t e d i n o t h e r s t u d i e s
(Lee and o t h e r s , 1981; Anderson and o t h e r s , 1980; Hampton, i n p r e s s ) .
Sediment f a i l u r e i n r esponse t o l a r g e ea r thquakes c e r t a i n l y i s a p o s s i b i l i t y ,
b u t t h e p o t e n t i a l i s not a s g r e a t a s has been p r e d i c t e d for some d e p o s i t s of
s i l t i n t h e n o r t h e a s t Gulf of Alaska ( c y c l i c s t r e n g t h a t 1 0 c y c l e s a s low a s
40% of t h e s t a t i c s t r e n g t h ; Lee and Schwab, i n p r e s s ) and v o l c a n i c a s h on t h e
Kodiak Shelf ( c y c l i c s t r e n g t h a t 1 0 c y c l e s i s 1 2 % of t h e s t a t i c s t r e n g t h ;
Hampton, i n p r e s s ) . The d e p o s i t of Katmai a s h i n She l ikof S t r a i t was n o t
s u b j e c t e d t o g e o t e c h n i c a l t e s t i n g . However, i t s i n s i t u d e n s i t y i s so g r e a t
t h a t normal g r a v i t y c o r i n g d e v i c e s cou ld n o t p e n e t r a t e t h e Layer. The
r e l a t i v e d e n s i t y appears t o be high and t h e r e f o r e t h e l i q u e f a c t i o n p o t e n t i a l
is low. The p o s s i b i l i t y that more deep ly b u r i e d a s h l a y e r s are p r e s e n t and
might be h i g h l y s u s e p t i b l e t o l i q u e f a c t i o n canno t be e v a l u a t e d w i t h t h e
i n f o r m a t i o n p r e s e n t l y a v a i l a b l e .
REFERENCES
American Society f o r T e s t i n g and M a t e r i a l s , 1976, Annual Book of ASTM
Standards . P h i l a d e l p h i a , ASTM, 485 p.
Anderson, K.H., Pool, J . H . , Brown, S.F., and Hosenbrand, W.F., 1980, C y c l i c
and s t a t i c l a b o r a t o r y t e s t s on Drammen c l a y . J o u r n a l of t h e Geotechn ica l
Engineer ing D i v i s i o n , ASCE, v. 106, p. 499-529.
Bishop, A.W., and Henkel, D . J . , 1964, The Measurement of S o i l P r o p e r t i e s i n
t h e T r i a x i a l Tes t . London, Edward Arnold L t d . , 228 p.
Bordovskiy, O.K., 1965, Accumulation of o r g a n i c m a t t e r i n b o t t o s sediments .
Marine Geology, v. 3, p. 33-82.
Bordovskiy, O.K., 1969, Organic m a t t e r of r e c e n t sediments of the Caspian
Sea. Oceanology, v. 9, p. 799-807.
Busch, W.H., and K e l l e r , G.H., 1981, The p h y s i c a l p r o p e r t i e s of Peru-Chile
c o n t i n e n t a l margin sediments - t h e i n f l u e n c e of c o a s t a l upwel l ing on
sediment p h y s i c a l p r o p e r t i e s . Jour . Sedimentary Pe t ro logy , v. 51, p. 705-
719.
Cassagrande, A., 1948, C l a s s i f i c a t i o n and i d e n t i f i c a t i o n of s o i l s .
~ r a n s a c t i o n s , ~ m e r i c a n Soc. C i v i l Engineers , v. 113, p. 901-9Yl.
Gardne r , J.V., Dean, W.E., and V a l l i e r , T.L., 1980, Sedimentology and
g e o c h e m i s t r y o f s u r f a c e s e d i m e n t s , outer c o n t i n e n t a l s h e l f , s o u t h e r n
B e r i n g Sea. Marine Geology, v. 35, p. 299-329.
Hampton, M.A., i n p r e s s , G e o t e c h n i c a l framework s t u d y of t h e Kodiak S h e l f ,
Alaska . U.S . G e o l o g i c a l Survey Open-File Repor t .
Hampton, M.A., Johnson, K.H., T o r r e s a n , M.E., and W i n t e r s , W . J . , 1981,
D e s c r i p t i o n of s e a f l o o r s ed imen t and p r e l i m i n a r y geo -env i ronmen ta l report,
S h e l i k o f S t r a i t , Alaska. U.S. G e o l o g i c a l Survey Open-File Report 81-1133,
86 p.
Hampton, M.A., and w i n t e r s , W. J., 1981, Env i ronmen ta l geo logy of S h e l i k o f
S t r a i t , OCS s a l e a r e a 60, Alaska. P r o c e e d i n g s 1 3 t h O f f s h o r e Technology
Confe rence , p. 19-34
Herrmann, H. G., Rocker, K . , and Babineau , P . H . , 1 9 7 2 , LOBSTER and FYS:
Devices f o r m o n i t o r i n g long- term seafloor f o u n d a t i o n b e h a v i o r . Naval
C i v i 1 E n g i n e e r i n g L a b o r a t o r y , T e c h n i c a l R e p o r t R-775, 63 p.
K e l l e r , G.H., Lambert , D.N., and B e n n e t t , R.H., 1979, G e o t e c h n i c a l p r o p e r t i e s
of c o n t i n e n t a l s l o p e deposits - Cape H a t t e r a s t o Hydrographer Canyon.
Soc. Economic P a l e o n t o l o g i s t s and Mineralogists S p e c i a l P u b l i c a t i o n 27, p.
131-151.
Ladd, C.C., and F o o t t , R,, 1974, New d e s i g n p rocedure f o r s t a b i l i t y of so f t
c l a y s . Journa l of t h e Geo techn ica l Eng ineer ing D i v i s i o n , ASCE, v. 100, p.
763-786.
Lambe, T.W., 1951, S o i l T e s t i n g f o r Engineers . New York, John Wiley and s o n s ,
165 p.
Lambe, T.W., and Whitman, R.V., 1969, S o i l Mechanics. N e w York, John Wiley
and s o n s , 553 p.
L e e , H.J., Edwards, B.D., and F i e l d , M.E., 1981, Geo techn ica l a n a l y s i s of a
submarine slump, Eureka, C a l i f o r n i a . Proceedings 1 3 t h Of f shore Technology
Conference , p. 53-65.
L e e , H . J . , and Schwab, W.C., i n p r e s s , Geo techn ica l framework, n o r t h e a s t Gulf
of Alaska. U.S . Geo log ica l Survey Open-File Repor t .
L i s i t z i n , A.P., 1972, Sed imenta t ion i n t h e World Ocean. Soc. Econonic
P a l e o n t o l o g i s t s and M i n e r a l o g i s t s S p e c i a l P u b l i c a t i o n 1 7 , 218 p.
Mayne, P.W., 1980, Cam-clay p r e d i c t i o n s of undra ined s t r e n g t h . J o u r n a l of t h e
Geo techn ica l Engineer ing D i v i s i o n , ASCE, v. 106, p. 1219-1242.
M i t c h e l l , J . K . , 1976, Fundamentals of S o i l ~ e h a v i o r . N e w York, John Wiley and
Sons, I n c , , 422 p.
Muench, R.D., and Schumacher, J.D., 1980, P h y s i c a l o c e a n o g r a p h i c and
m e t e o r o l o g i c a l c o n d i t i o n s i n t h e n o r t h w e s t Gulf of Alaska . NOAA T e c h n i c a l
Memorandum ERL PMEL-22, 147 p.
Nayudu, Y.R., 1964, Vo lcan ic a s h d e p o s i t s i n t h e Gulf of Alaska and problems
of c o r r e l a t i o n of deep-sea ash d e p o s i t s . Marine Geology, v.1, p. 194-212.
O d e l l , R.T., Thornburn , T.H., and McKenzie, L.T., 1960, R e l a t i o n s h i p s of
A t t e r b e r g l i m i t s t o some o t h e r p r o p e r t i e s o f I l l i n o i s s o i l s . P r o c e e d i n g s
of t h e S o i l s S o c i e t y of A m e r i c a , v. 24, p. 297-300.
P r a t t , R.M., S c h e i d e g g e r , K.F. , and Kuln, L.D., 1973, Vo lcan ic a s h from DSDP
s i t e 178, Gulf of Alaska . I n i t i a l R e p o r t s o f Deep Sea D r i l l i n g P r o j e c t ,
V. X V I I I , p. 833-834.
Rash id , M.A., and Brown, J.P., 1975, I n f l u e n c e of mar ine o r g a n i c compounds on
e n g i n e e r i n g p r o p e r t i e s of remolded sed imen t . E n g i n e e r i n g Geology, v. 9,
p. 141-154.
R i c h a r d s , A.F., 1962, I n v e s t i g a t i o n of deep-sea s e d i m e n t c o r e s , 11. Mass
p h y s i c a l p r o p e r t i e s . U.S. Navy Hydrographic O f f i c e Tech. Rept . 106, 146
Pa
R i c h a r d s , A.F., and Hamilton, E.L., 1967, I n v e s t i g a t i o n s of deep-sea s e d i m e n t
cores, 111. C o n s o l i d a t i o n . ~ n : - R i c h a r d s , A . F . (ed.), Marine
Geo techn ique , Urbana, U n i v e r s i t y of I l l i n o i s P r e s s , p. 93-117.
2 2
Skempton, A.W., 1944, Notes on the c o m p r e s s i b i l i t y of c l a y s . G e o l o g i c a l
S o c i e t y of London, Q u a r t e r l y J o u r n a l , v. 100, p. 119- 35.
T e r z a g h i , K., 1955, I n f l u e n c e of g e o l o g i c a l f a c t o r s on t h e e n g i n e e r i n g
p r o p e r t i e s of s e d i m e n t s . Economic Geology, 50 th A n n i v e r s a r y Volume 1905-
1955, p. 557-618.
T e r z a g h i , K., and Peck, R.B., 1948, S o i l Mechanics i n E n g i n e e r i n g Practice.
New York, John Wiley and Sons.
von Huene, R., 1979, S t r u c t u r e of t h e o u t e r c o n v e r g e n t margin o f f Kodiak
I s l a n d , A laska , from m u l t i c h a n n e l s e i s m i c r e c o r d s . In: Watkins , J.S.,
Montade r t , L., and Dicke r son , P.W., ( e d s . ) , G e o l o g i c a l and Geophys ica l
I n v e s t i g a t i o n s of C o n t i n e n t a l Margins , AAPG Memoir 29, T u l s a , American
A s s o c i a t i o n of Pe t ro l eum G e o l o g i s t s , p. 261-272.
Whitney, J., Holden, K.D., and Lybeck, L., 1980a , I sopach map o f Qua te rna ry
g l a c i a l - m a r i n e s e d i m e n t s , o u t e r c o n t i n e n t a l s h e l f , S h e l i k o f S t r a i t ,
Alaska. U.S . G e o l o g i c a l Survey Open-File R e p o r t 80-2036, 1 p.
Whitney, J., Hoose, P.J . , Smith, L.M., and Lybeck, L., 1980b, Geo log ic c r o s s
s e c t i o n s of t h e o u t e r c o n t i n e n t a l s h e l f , S h e l i k o f S t r a i t , Alaska . U . S .
G e o l o g i c a l Survey Open-File Repor t 80-2036, 1 p.
Wissa , A.E., C h r i s t i a n , J .T. , Davis , E.H., and Heibe rg , S . , 1971,
C o n s o l i d a t i o n a t c o n s t a n t r a t e of s t r a i n . J o u r n a l of t h e S o i l Mechanics
and Founda t ion D i v i s i o n , ASCE, v. 97, p. 1393-1410.
2 3
Table 1. Consolidation test results.
Depth . in a a
VO vm C" X lo-': S t a t i o n core C c number (cm (kPa) (kPa 1 OCR
Table 2. S t a t i c t r i a x i a l s t r e n g t h test r e s u l t s .
Depth I
in o C Su I
S t a t i o n core Induced S / O
OCR u C 4'
number (cm) ( k P a ) (kPa (degrees )
Table 2. ( c o n t i n u e d )
Depth I
in o C Su 1
S t a t i o n core Induced S"'"c 9 Number (cm) (kPa) OCR (kPa (degrees )
Table 3 . Dynamic triaxial s trength test r e s u l t s .
Depth I
in u T cyc'su
Cycles C
Station core Induced to number (cm (kPa ) OCR ( % ) f a i l u r e
FIGURE CAPTIONS
1. Loca t ion map of the study a r e a i n She l ikof S t r a i t .
2. A. T r a c k l i n e s of con t inuous s e i s m i c - r e f l e c t i o n p r o f i l e s . S o l i d l i n e s
r e p r e s e n t a r e g i o n a l su rvey c o n t r a c t e d by the USGS Conserva t ion D i v i s i o n ,
and dashed l i n e s r e p r e s e n t s i t e su rveys on cruises of t h e R/V S .P. Lee
(1980) and NOAA s h i p Discovere r (1981).
B. Loca t ions of sediment sampl ing s t a t i o n s .
3. Bathymetry of She l ikof S t r a i t , 20-m con tour i n t e r v a l . Depths c o r r e c t e d
t o mean lower low wate r .
4. Thickness of sed imenta ry u n i t s of p robab le P l e i s t o c e n e and younger age .
Contour i n t e r v a l : 50 meters e x c e p t f o r t h i c k n e s s g r e a t e r than 500 rn
where con tour i n t e r v a l i s 100 rn.
5 . R e p r e s e n t a t i v e s e i s m i c - r e f l e c t i o n p r o f i l e s showing s e i s m i c - s t r a t i g r a p h i c
u n i t s .
6. Thickness of h i g h e s t s e i s m i c - s t r a t i g r a p h i c u n i t that covers most of t h e
s e a f l o o r of She l ikof S t r a i t . Contour i n t e r v a l : 20 m.
7. Pie-diagrams showing r e l a t i v e abundances of t e x t u r a l c l a s s e s i n s e a f l o o r
sed iment samples.
8. Mean g r a i n size of s e a £ I ~ J o ~ sediment , i n p h i - u n i t s .
9. Sediment accumulat ion r a t e s , i n cm/100 y r .
10. Water c o n t e n t ( p e r c e n t d r y weigh t ) a t 1-rn dep th i n sediment c o r e s .
11. Bulk sediment d e n s i t y (qn/crn3) a t 1 - m dep th i n sediment c o r e s .
12. Average g r a i n s p e c i f i c g r a v i t y i n sediment c o r e s .
13. Average l i q u i d l i m i t ( p e r c e n t d r y w e i g h t ) i n sediment c o r e s .
14. Average p l a s t i c l i m i t ( p e r c e n t d r y weigh t ) i n sediment c o r e s .
15. Average p l a s t i c i t y index i n sediment c o r e s .
16. Liquid l i m i t ve r sus g r a i n s i z e .
17. P l a s t i c limit versus g r a i n size.
la. P l a s t i c i t y index versus g r a i n size.
19. P l a s t i c i t y c h a r t .
20. Vane s h e a r s t r e n g t h (kPa) a t lm dep th i n sediment cores.
21. Vane shear s t r e n g t h ve rsus water c o n t e n t .
22. Average o r g a n i c carbon c o n t e n t i n sediment c o r e s .
23. Average calc ium carbona te c o n t e n t i n sediment c o r e s .
24. Graph of compression index versus liquid l i m i t .
25. Graph of e f f e c t i v e a n g l e of i n t e r n a l f r i c t i o n versus p l a s t i c i t y index .
S o l i d l i n e shows e m p i r i c a l r e l a t i o n d e r i v e d by Lambe and Whitman (1969) ;
dashed l i n e i n d i c a t e s l i m i t s of t h e i r d a t a .
26. Graph of normalized undrained s h e a r s t r e n g t h ve rsus o v e r c o n s o l i d a t i o n
r a t i o .
27. Graph of c y c l i c stress l e v e l versus number of c y c l e s t o f a i l u r e .
-FJW 4 I
I t SE+ I
I
t
P l l l l l l l l , , meters
1000 I
I t central platform I I
I marginal chamel
, .
Fig. 5
10 0 8 7 6 5 4 3
Fig . 16 mean grain size (9)
Q 8 7 6 5 4 3 Fig. 17 mean grain size (0)
4 8 - -
10 0 8 7 6 5 4 3 Fig. 18 . mean grain size (0)
49
0s
Plasticity index
Fig. 26 OCR
Appendix A. Index property charts for sediment cores from Shel ikof Strait.
Station 508 Locafjon 57O21.01 'N 1 5 ~ ~ 3 6 . 4 1 'W Water depth 27om
Depth (cml
rn 0
200
2 5 0
300
Grain slze (weight 96)
Bulk den I ty 8 lgmlcm 1
b
Bulk density at lm.: 1 . 5 6
I b
s i l t
Water content Plasticity Atterberg limits- Index (% dry weight)
0 50 100 1% 0 50 - I
c l a y
Water content Average at Im.: 87 .2 plasticity Average plastic index: limit: 36 31) Average liquid limit: 65
Llquldit y index
0 1.02.0
Liquidity index at Im.:
1.58
Grain Organlc speciflc carbon gravity (%dr wei ht)
21) 2.5 3.0 0 7 2 8 4
Average Average grain speclflc organic &avi t y : carbon:
2.84 0.931
Carbonate (%dry weight)
0 t 2 3 4
T C ' I
b
Average carbonate:
1 . 2 9 1
Vane bhear strength (kPa)
0
Vane shear strength at lm*
1 - 5 8
Station 509 Location ~ 7 ~ 2 1 . 2 9 ~ ~ 15S008.66'N' Waferdepth 225111
Grain slre (welght %I
Depth
Bulk den Ity t (grn/cm 1
(cm)
rn P
50
1.0 1.5 2.0 r r I I l ~ ~ ~ ~ n n A
b
b I D
I
Bulk density at Im.: 1.46
-- -
Water content Plastlclty At terberg limits- lndex (% dry weight)
0 50 100
Water content Average at dm.: 104.5 plasticity Average plastic index: limit: 40 34 Average liquid limit: 75
- 100 -
- 150-
Llquidity Grain Organtc index speciflc carbon
2 0 0
gravity (%dr we4 ht) 0 1.0 2.0 2.0 2.5 3.0 0 7 2 ! 4
. - - - ?77
Liquidity Average Average index grain specific organic at lm.: gravity: carbon:
3 . 5 6 2 . 8 1 1.009
Carbonmte (%dry weight)
2 5 0 -
T' I
Average
C
- . - *
carbonate: 0 .990
300-
Vane shear
Vane shear strength at lm.: 6%
Station 511 Locsfion57O39.08~~ 1 ~ 4 ~ 5 0 . 1 4 ~ ~ Waterdepth 2141-11
Bulk den I ty Water content a Plasticity 8 (gmlcm ) Atterberg I l m i t s H Index (% dry weight)
1.0 1.5 2.0 0 50 1 0 0 150 0 50 Depth
Bulk density Water content Average a t Im. :1 .49 atlrn.:100.6 plasticity
Average plastic index: limit: 36 36 Average liquid limit: 72
(crn)
0 W
50
100-
150-
- -
.. - b
- - -
200 - -
250
- 300-
t lqu id l t y Grain Organic Carbonate Vans ahear index 8peclfic carbon (%dryweight) strength
gravity (%dr wei ht) (kPa1 01.02.0 2.0 2.5 3.0 () 7 2 8 4 0 1 2 3 4 0 50
Liquidity Average index grain specif lc organic carbonate: strength at 1 m.: gravity : carbon: 0 .873 at l m -
1 .74 2 . 8 4 1.075 6.70'
1 3
&
I L
Average Average Vane shear 1
$ 0 =E m .e OF 5 ;go C O O
I 8, . O h -
Station 513 Location 5 7 0 5 4 . 5 ' ~ 1 5 4 ~ 1 9 . 8 ' 1 ~ Waterdepth 205m
Depth
0-l Ln SO"
100-
1 so -
Grain 812e twelght 96)
200
0204qeoso
Fsiit Z c l a y 1 1 1 1 1 1 1
- - - - -
Bulk den ity S (gm/cm 1
Bulk density at lm.: -
250
- - - - - .;
6
Llquidit y index
Water content o Plastlclty Atterberg l i m i t s w index (% dry weight)
300- tiquidit y index at lm.:
Qraln Organlc s ~ s c l f l c carbon
1500 50 r l ~ 1 7 1 I
a
0
Average Average grain speclfic organic
Water content Average at lm.: plasticity Average plastic index: limit: 37 30
50 100 f " m ' l " l r ~
+I
gravity: carbon: 2 . 7 7 0 -863
Carbonate (Wdryweight)
0 1 2 3 4
Average carbonate:
1-10
Vane shear strenath
Vane shear strength at lm.:
Average liquid limit: 67
1 8 - n-7
- Y C C s .E .F - - m s i 5 ? % - - o w * ~ e G g : gl u @ a = # 3:ewo-
: -
-:
- - I
Station 515 Location 57059 .o I N 154027.3 ' W Water depth 238m
Grain size (welght %I
Depth (cm)
0 4
200
250
300
Bulk den I ty Water content Plestlcity Liquidity Grain 8 ( g m l c m 1 Atterberg limits- Index index specif lc
Bulk density Water content Average Liquidity Average at lm.: at lm.: plasticity index grain specific
Average ptastic index: at Im.: gravity: limit: 2 . 6 5 Average liquid
(% dry weight)
Organlc Carbonate Vane shear
0
(%dry weight) strength I (kPa)
0 1 2 3 4 0 50 50 100 1 8 1 ' ' ' ' 1 " 1 ' 1
Average Average Vane shear organic carbonate: carbon: 1 .02 at lm.:
0 .721
limit:
Station 516 Locsfjon s s 0 0 0 . 3 t ~ 154010.6'1t~ Water depth 205
Depth ( c m l
0-l m
2 00
250
300
Graln size (weight %)
020406060 1 1 1 1 1 1 1 1
silt c l ay
Bulk den i t y Water content e Plasticity Ltquldlty Graln f Organlc Carbonate Vans shear (gm/crn 1 Atterberg I i r n i t s H lndex index specific carbon (%dryweight) strength
(% dry weight) gravity ( I d r wei ht) (k Pa) 1.0 1.5 2.0 0 50 1 W ,500 60 01.02.0 2.0 2.5 3 . 0 0 7 2 8 4 0 1 2 3 4 0 50
a
8ulk density Water content Average Liquidity Average Average Average Vane shear at lm.: at lm.: plasticity index grain speclflc organic carbonate: strength
Average plastic index: at lrn.: gravity: carbon: 1 .05 at tm.:
limit: 2.65 0 .898 Average liquid limit:
I " 1 I f I l [ I 1 . 1 .
-
b " Itt ?? * F k o so
t o u
Station 518 Location 58O00.3 I N 1 5 3 ~ 5 1 . 6 w Water depth 180m
Graln slre (weight %I
Depth (cm)
4 0 50
100-
Bulk den I ty Water content Plast lc l ty Llquldlty Grain 8 Organic Carbonate Vane shear (gm/cm Atterberg l i m i t s w index Index specif lc carbon (%dryweight) strength
I% dry weight) gravi ty (%dr wei ht) (k Pa) 1.0 3.5 2.0 O 50 3 0 0 150 0 50 0 1.02.0 2.0 2.5 3.9 O 7 2 8 4 0 1 2 3 4 0 50
-
n -
150
Butk density Water content Average Liquidity Average Average Average Vane shear at Im.: at lm.: plasticity index grain specffic organic carbonate: strength
Average ptastic index: at lm.: gravity: carbon: 0.940 at 1 m.: limit: 2 .62 1.104
Average liquid limit:
m ' 1 . 1 ' 1 1 1 1 I r I I I
t
- - - - -
l r r I l l l j l ~
i
I F T
t
1
I I
t
200
2 5 0
300-
- C - - - - - - - *
Station 524
Grain sire (welght % I
Bulk den I t y 8 (grn/crn 1
Bulk density at lm.:
Llquldlt y index
Water content Plastlclty Atterberg I h i t s H Index (% dry weight)
Liquidlt y index at Im.:
0 50 100 l " " i " " 1
Water content
Water depth 175m
Grain Organic speclflc carbon
at lm.: plasticity Average plastic index:
1500
grain specific organic gravity : carbon:
50 1 1 1 1 I I
Average
Carboneta (%dryweight)
carbonate:
Vane shear strength (kPa1
0 50
Vane shear strength at Im.:
limit: Average liquid limit:
Depth (cm)
1 so
200
Station 525 Location 5 s 0 2 3 . 7 ' ~ 1 ~ 3 ~ 3 7 . 2 ' W Water depth ls8m
Grain size (welght %I
Bulk den Ity 8 (gm/cm 1
0201080# I I I 1 1 I W I I
sand s i l t
Bulk densit at im.: 1 - 8 2
Liquldit y index
Water content Plastlcl ty Atterberg I i m i t s H index (% dry weight)
Liquidity index at lm.:
1 . 4 1
Grain Organlc speclflc carbon
1500 50 I I I I I I -
I Average
0
Average Average grain speclfic organic at lm.: 45.2 plasticity
Average plastic index: limit: 2 7 13 Average llquid limit: 39
50 100 I ' I T ' 1 ' l T ' 1
i Water content
gravity : carbon: 2.79 0 .882
Carbonate (%dry weight)
Average carbonate:
1 . 0 3 4
Vane shear strenath
Vane shear strength at im.:
22 .59
Depth (cm) -
so - 03 0
100- - *
b - 150-
- - - 200 - -
250 - - -
300-
Station 528 tocstjon 58039 -4 I N 15300.7 'W Water depth 159m
Graln s i ts (weight %)
Bulk den Ity 8 (gmjcrn 1
Bulk density at lm.: J - J L
Water content Plastlclty Atterberg limits- Index (% dry weight)
0 50 100 1500 50 P---
- Water content Average at lm.: 46 .9 plasticity Average plastic index: limit: 26 11 Average liquid Ilmit: 37
at lm.: gravity: carbon: 2 . 2 3 2 - 7 3 0 .643
Carbonate Vane shear (%dry weight) strength
Average Vane shear carbonate: strength
2 . 1 9 7 at Im.: 16.91
Station 531 Location 5 8 0 5 4 . 9 ~ ~ 15z037.3tw Water depth
Grain slze (welght 96)
Depth (cm)
SO
Bulkden ity W a t e r c o n t e n t * Plasticity Liquidity Grain 8 Organic Carbonate Vane 8hear (gm/cm 1 Atterberg l i m i t s H index index speclflc carbon (%dryweight) strength
(% dry weight) gravity (lbdr we! ht) (k Pa)
-
1.0 1.5 2.0 0 50 100 150 0
100 -
150 L
200
250
300
50 ; 2 P l I I r r I I 2.5 3.007 I - 2 ! 4 T ' f 7 0 1 2 3 4 I , -
0 1-1 I I 50
C
b - - - - - - * - -
I
. Bulk density Water content Average Liquidity Average Average Average Vane shear at lm.: at lm.: plasticity index grain specific organic carbonate: strength
Average plastic index: at lm.: gravity: carbon: 3 . 2 5 at Im.: Hrnit: 0 .388 Average liquid limit:
-3 Zbg = N
F 52". E t o o
0 - r 8
Ql p ..a p : ~ ? 8 3" <Ebb
Station 535 Lo~afion58~37.0~N 1 5 ~ ~ 4 2 . 0 ~ ~ Water depth 98m
Grain size (weight %I
Depth
Q3 4
1 0 0 -
1 5 0 -
2 0 0 -
Bulk den i ty Water content Plasticity Liquidity Grain S Organlc Carbonate Vane shear (gm/crn Atterberg I h i t s H index index apeclffc carbon (%dryweight) strength
(% dry weight) gravity ( I d r we1 ht) (kPa) 1.0 1.5 2.0 0 50 100 1 W O 5 0 . 01.02.0 2.0 2.5 3.00 7 2 ! 4 0 1 2 3 4 0
- - - - - - - - - C
Bulk density Water content Average Liquidity Average Average Average Vane shear at Im.: at lm.: plasticity index grain specific organic carbonate: strength
Average ptastic index: at lm.: gravity: carbon: 21.67 at lm.: limit: 2.76 0 . 2 0 9 Average Iquid limit:
250
300-
- - - - - -
I € 1
;
a 1 f , !
a I I Z I ] I l ~ l ' ~ f l l l
a 1 . r . 1 .
i
Station 538 Location s s 0 2 s - 2 ' N 153"oo .2'w Water depth 190m
Depth t c m )
LQ 0
200
250
300
Graln size (weight %I
Bulk den ity Water content Plastlclty LIquldity Grain J Organic Carbonate Vane shear (gmlcrn 1 Atterberg limits- index index specific carbon (%dryweight) strength
(% dry weight)
Bulk density Water content Average Liquidity Average Average Average Vane shear at Im.: 1.61 at Im,: 74 . 7 plasticity index grain specific organic carbonate: strewth
Average plastic index: at lm.: gravity: carbon: 1 . 4 2 at lm.: tlmit: 33 2 9 1 . 4 6 2 . 7 8 0 . 8 7 1 16 . O Y
Average liquid limit: 62
Station 539 Location 58'21 - 3 ' ~ 153'12 - 4 ' 1 ~ Wafer depth 175m
Grain sirs (welght %I
Depth (cm)
w so
- -
020408080
Butk den i t y Water content Plasticity Liquidity Oraln S Organlc Carbonate Vane shear (grnicrn 1 Atterberg I i rni tsH Index index specific carbon (%dry weight) strength
(% dry weight) gravity ( I d r wei ht) (k Pal .O 1.5 2.0 0 50 1 0 0 1500 W 01.02.0 2.0 2.5 3.0072!4 0 1 2 3 4 0 50
s i l t
I
Bulk densit
c l a y
w 1 D a
looL
5 Water content Average Liquidity Average Average Average Vane shear at lm.: 1.4 at tm.: 109.7 plasticity index grain specif lc organic carbonate: ,trewth
Average plastic index: at Im.: gravity: carbon: 1 .70 at Im.: limit 2 . 5 2 1.102 9 .07 Average tiquid limit:
1 1 1
1
L
L - 150
C
I I I I l I 1 1 1 I I 1 1 -
1 I
Station s40 Location ~ 8 ~ 2 1 . 5 ' ~ 153O07.6'W Waterdepth Z l O r n
Graln sirs (welght %I
Depth (cm)
19 5 0 -
N
100-
150-
Bulk den I ty Wster content Plastlclty Liquldlty Qraln 8 Organlc Carbonate Vane shear (gm/cm ) Atterberg I i rn i tsH index index specific carbon (%dry weight) strength
(% dry weight) gravity (%dl wei ht) (kPa) 1.0 1.5 2.0 0 50 100 1500 50 01.02.02.0 2.5 3.0072!4 0 1 2 3 4 0 50 -
- - : : 200
Bulk den;I1ll Wetter content Average Liquidity Average Average Average Vane shear a t l m . : . a t I m . : 7 4 , 0 plasticity index grain specifk organic carbonate:
Average plastic index: at 1 m.: gravity: carbon: 1 . 1 0 at lm.:
limit: 2 . 7 6 0 .799 15.86
Average liquid limft:
C - - - -
I 1 1 I '
: 250 -
300-
! 7 1 1 ] & ~
Station 541 Location ~ 8 ~ 1 5 . s Y x 153022 - 0 I I Y Water depth 167m
Graln size (welght %I
Depth I c m )
cD 50 W
100-
150C
200
Bulk den I ty Water content Plasticity Llquldlty Grain 8 Organic Carbonate Vane shear (grn/cm ) Atterberg I i rni tsH index Index specific carbon (%dryweight) strength
(% dry weight) gravity (Jdr wei h t l (kPa) .O 1.5 2.0 0 50 100 1500 50 01.02.0 2.0 2.5 3 . 0 0 7 2 8 4 O f 2 3 4 0
- rm -
L
- - - - - - - - - b -
1 1 -
A 1
250
Bulk density Water content Average Liquidlt y Average Average Average Vane shear at lm.: at Im.: plasticity index grain specif lc organic carbonate: strength
Average plastic index: at tm.: gravity: carbon: .270 at lm.: limit: 3'3 24 1.082 Average liquid limit: 63
- - - P -
300-
H * 1 1 1 1
a
L
~ I I I T I I I
L
k g c .. a t $ O h -
> a m
I l l l l . l l l l l l I l l l I l . I
f - 0 0 0 0 0 0 n o n o Y)
r 0
E 5 v PU 04 m P -
Station 545 Location 5 8 O 2 2 - 5 ' N 153O53.5 ' w Water depth 175.
Grain 812s (weight %)
Depth (crn)
a 50 rn
Bulk den tty Water content Plasticity Llquldtty Qraln d Organtc Carbonrta Vans shear (gm/cm ) Atterberg l i m i t ~ H index Index speclflc carbon (%dryweight) 8trsngth
(% dry weight) gravity %dr wel (kPe1 1.0 1.6 2.0 0 50 100 150 0 50 0 1.02.0 2.0 2.5 36 0 r 2 , O ! 2 3 4 0 50
-
! 1 - ~ 100-
i-
150- -
Bulk density Water content Average Liquidity Average Average Average Vane shear
a t lm. :1 .64 a t l m 6 9 . 1 plasticity index grain speclfic organic carbonate: strength
index: at lm.: gravity - carbon: 0.710
Average Iastic f9
at IF.'
limit: 2 0 2 . 0 2 2 . 7 9 0 .663 & Average liquid limit: 49
,
250 w : , : 2 , , H - - - - m -
H
300 -
Depth
ID CO
200
250
300
Station 547 tocation ~ 8 ~ 3 3 . 0 ' ~ 153034 - 4 ' ~ Water depth 89m
Graln slze (welght %)
Bulk den Ity 8 (gm/cm 1
Bulk density at Im.:
Liquidity Grain Organlc index speciflc carbon
gravity (%dr wei ht) 01.02.0 2.0 2.5 3.0 0 7 2 8 4
Water content Plasticity Atterberg I i m i t s H Index (% dry weight)
Liquidity Average Average index grain specfflc organic at lm.: gravity: carbon:
2 . 7 9 0 .591
Carbonate (%dry weight)
1500 50 F I I I I I '
I
Average
0 0 1 2 3 4 I "
Average
at lm.: plasticity Average plastic index: limit: 28 14 Average Iquid limit: 42
50 100 1 " " I " " I
H "i
Water content carbonate:
1.05
Vane shear strength
Vane shear strength at lm.:
7 4
$,g i='b a'C 0 9 & a n > P z = C O O
Station 551 Location 5 8 0 ~ 3 . 6 ' ~ 1 5 2 0 5 4 . 4 1 ~ Water depth lssm
Depth (cm) -
Bulk den Ity J (gm/cm 1
50 P
Bulk density at lm.:
-
llqutdity Oraln Organtc index s ~ e c i f l c carbon
Water content Plastlclty Atterberg 1imitsb-i index (% dry weight)
0 N
100-
Liquidity Average Average index grain specific organic at Im.: gravity: carbon:
2 - 7 6 0 . 8 0 1
0
m
-
Carbonate (%dry weight)
Average carbonate:
2 . 1 4 at Im.: ptasticit y Averagl glastic index: limit: 10
50 fOO ~ ' " ' ~ ' " ' I
H r
Water content
150-
200
250
300-
Vane shear
50 1 1 1 F 1 1 -
Average
- b
L
L - - + - - - - . -
rtrsngth (kPa)
0 I 1 I I
Vane shear strength at lm.:
Average liquid limit: 34
r Q
go,
* Q O a 0 I w
E -3 b N
2 c . F 8 0 =z % 0~~1 g $5 g':
5 0 0 , > P k o
llcO C O O
Q a 0
u
b 22;l a 0 >" 5 a (3 ..a 0
CI g a r . O $ o
L *= . z r 4
S 2 a z 2 0 2 en
a h - > m Q
Station 647 Location 57 '59 - 8 ' ~ 154010.7 'W Water depth 22om
Depth (cm) -
5 0 -
Average lastic f5
index: limit: 3 1
Bulk den I t y Water content Plastlclty 8 (grntcrn 1 Atterberg I i m i t s H Index (% dry weight)
P 0 LC
1 0 0 -
1 5 0 -
200
250
300-
Llquldlt y Qraln Organtc Carbonate Vane shear Index speclflc carbon (%drywelght) strength
gravity (%dr wei ht) (kPa1 01.02.0 2.0 2.5 3.0 0 r 2 ! 4 0 1 2 3 4 0 1.0 1.5 2.0
l ~ ~ ~ l , ~ r ~ 7 ,
1 L - - - - m - - - - - - - - b -
Liquidity Average Average Average Vane shear index grain specffic organic carbonate: strength at tm.: gravity: carbon: at Im:
1.11 2 .58 8 -81 Average I! id iirnlt: 6p
Bulk density Water content Average at tm.: 1.57 atlm.: 76.4 ptasticity
0 50 700 l " ' r l " " l
I; -
1500 50
.- m E Q .: = E IS' 2;
Station 654 Water depth 232m
Depth
m aoL
100-
f50- L .
200 - - - - - 250 - - -
C
L
3 0 0 -
Bulk den i ty Water content Plasticity Liquidity Qraln 8 Organlc Carbonate Vans shear (grntcrn 1 At terberg I i m i t s H index index specific carbon (%dryweight) 8trsngth
(% dry weight) (!(Pa) 1 1.5 2.0
a
Bulk density Water content Average Liquidity Average Average Average Vane shear at lm.: at lm.: plasticity index grain specific organic carbonate:
Average plastic index: at Im.: gravity: carbon: 0 .870 at lm.: limit: 2 . 6 1 1 .006 Average liquid limit:
0 50 100 . 1500 50 0 50 I I f I
0 1 . 0 2 . 0 2.0 0 , 2 3 4 - 1 1
,o c -- f . ! g t $$
o O u C O O
0 ' .; c o , 2 ' a g;i ax 0.:@
E
$% $
$ E z . . . , C - $ r c g - r n - > E W E S m u = < =
Station 658 Location 58010.6 'N 1 ~ 3 ~ 3 2 . 6 ~ 1 ~ Water depth 190m
Grain slze (weight %I
Depth 0204080w ~ i r l f ~ l l f ' , silt. c l a y
(cm)
a0
- im
Bulk den I ty Water content Plastlclty Llqufdlty Graln # Organic Carbonate Vanashear (gm/crn 1 Atterberg I l m i t s H index index speclflc carbon (%dryweight) strength
(% dry weight) gravity (%dr wei ht) (kPa) 1.0 1.5 2.0 50 1W 150 0 50 0 1.02.0 2.0 2.5 3.0 0 1 2 8 4 0 1 2 3 4 0 50
T I I I I I
100-
150-
200
250
300-
1 - - - - - - - - - - - - - - - - - -
I I , I I I I
" f I '
Bulk density Water content Average Liquidity Average Average Average Vane shear at Im.: at lm.: plasticity index grain specific organic carbonate: ,trmgth
Average plastic index: at lm.: gravity: carbon: at 7m.: Ilrnit: 50 30 2 . 5 5
liqvid lim#:
I I I I I
Station 659 Location 58'01. B ~ N 153028.5 + W Water depth 112m
Depth
Graln sirs (weight %I
(cm)
50
02040806U
sand
L
-
-
Bulk den lty d (grn/crn 1
Bulk density at lm.:
P P w
100-
Water content Atterberg I h i t ~ H (96 dry weight)
0 50 100 150
-
Water content at tm.: Average plastic limit: 2 1
Plastlclty Index
150
Average plasticity
200
250'
index: 16
- - - - - L
b
Liquldft y index
r
300-
0 f .02.0
a
Liquid# y index at lm.:
Grain Organlc Carbonate speclflc carbon (%dry weight)
Average grain speclf)c organic carbonate: gravity : carbon: 0.340
2.47 0 - 2 2 8
Vane shear strength (kPa)
0 6Q I l l 1
i
Vane shear strength at lm.:
Average liquid limit: 37
Station 664 Location 5 8 " s ~ . o o ~ 1~3~36.901: ' Water depth 174m
Depth (cm) -
50 - P N P
1oopm -
Graln sire (weight 96)
150-
Bulk den I ty 8 (grn/cm 1
- - - -
1.0 1.5 2.0 1 " ~ ' " ' ~ ' '
i
Bulk density at lm.:
Water content At terberg l i m i t s ~ (% dry weight)
0 50 fOO 150 l ' l ' r T ' ' ' l ~
200
250
300 Water content at f m.: Average plastic limit: Average liquid limit:
- - - - - - - - - - -
Plastlcl ty Liquidity Index index
0 50 l r l ~ y r l
Average plasticity
0 1.02.0
Liquidity index
index: at lm.:
Orain Organlc spsclfic carbon
grain specific organic gravity : carbon:
2 09
Carbonate (%dry weight)
Average carbonate:
Vane shear strensth
Vane shear strength at lm.:
