FAULTS OF T

HE LOS

ANGELES FIELD

TRIP

FAULTS OF THE LOS ANGELS FIELD TRIP How were the San Gabriel Mountains uplifted? –Kim Gloersen

How the Raymond, Hollywood, and Santa Monica faults are related? –Diego Furtado

How are we “blind” to some of our faults? – Hannah Shamloo

How the 1971 San Fernando and the 1994 Northridge earthquakes compare? –Miguel Frias-Rodriguez

How are fault features expressed in an urban environment? – Miguel Villasana

How is Los Angeles a city of faults? - Matt Rieman

HOW WER

E THE SAN

GABRIEL MOUNTAINS

UPLIFTE

D?

K I M G

L O E R S E N

One mountain said to the other across the rift "Hey, it's not my fault!"

PLATE MOVEMENTS 30 Ma. , subductive

tectonic movements occurred between the Farallon, North American, and Pacific plates.

20 Ma. the relative movements of the North American and the Pacific Plate changed from a head on head contact with the Farallon Plate to a lateral slipping against each other.

THE BIG BEND

The “big bend” of the San Andreas fault causes compression that pushes up the Transverse Ranges.

Perspective of Big Bend compressional areas, with the addition of thrust faulting from the Sierra Madre.

THRUST FAULTING

Compressional zones and thrust faulting.

North-south cross section of the San Gabriel Mountains

REFERENCES

Atwater, Tanya. "Implications of Plate Tectonics for the Cenozoic Tectonic Evolution of Western North America." Geological Society of America Bulletin 81.12 (1970): 3513-536. Print.

"Geology of the San Gabriel Mountains, Transverse Ranges Province." Western Region Geology and Geophysics Science Center. Western Earth Surface Processes Team, 26 May 2006. Web. 15 June 2013.

Masters, Nathan. "Rise of the Sierra Madre: A Brief History of the San Gabriel Mountains | LA as Subject | SoCal Focus | KCET." KCET. KCET, 30 May 2012. Web. 15 June 2013.

Phillips, Donna E. "Geology of the San Gabriel Mountains, Transverse Ranges Province." Western Region Geology and Geophysics Science Center. USGS, 1 Jan. 1990. Web. 15 June 2013.

RELATIONSHIP B

ETWEEN

THE SANTA MONICA,

HOLLYWOOD, A

ND

RAYMOND FA

ULTS.

B Y DI E

G O FU R T A D O

COMPRESSION ZONE The “BIG BEND”: Cause of Compression between the Pacific Plate and North American Plate

Mountains and faults are formed: San Gabriel Mountains and Santa Monica Mountains

Transverse Range Southern Boundary Fault System: Extends from east to west unlike other California mountains

TRANSVERSE RANGES FAULT SYSTEM Base of San Gabriel and Santa Monica

Mountains

West- trending system of faults that extends for 200 km

Oblique-slip, reverse-slip, and strike-slip

RAYMOND, SANTA MONICA, AND HOLLYWOOD FAULTSSANTA MONICA HOLLYWOOD RAYMOND

TYPE OF FAULT : Left-reverse Left-reverse Left-lateral (minor reverse) ▼ ▼ ▼

LAST KNOWNSURFACE RUPTURE: ~900 A.D ~800 A.D.

~1000 A.D PROBABLE MAGNITUDES: 6.0 - 7.0 5.8 – 6.5

6.0 – 7.0

• Santa Monica fault connects with Hollywood fault at west Beverly Hills Lineament

• Hollywood fault likely connects to Raymond fault at Los Angeles River floodplain

SLIP RATE (mm/yr):LENGTH:

0.27 – 0.39 0.33 – 0.75 0.10 - 0.22 40 km 15 km 26 km

REFERENCES• http://geomaps.wr.usgs.gov/archive/scamp/html/scg_flt.html• http://qcode.us/codes/malibu-general-plan/view.php?topic=ii-5_0-5_2-5_2_2&frames=on• http://www.data.scec.org• Kristin D. Weaver, Paleoseismology and Geomorphology of the Raymond Fault, Los Angeles County, California, Bulletin of the Seismological Society of America pp. 1409–1429, December 2000, P. 1410-1413.• James F. Dolan, Eldon M. Gath, Lisa B. Grant, Mark Legg, Scott Lindvall, Karl Mueller, Michael Oskin, Daniel F. Ponti, Charles M. Rubin, Thomas K. Rockwell, John H, Shaw, Jerome A.Treiman, Chris Walls, and Robert S. Yeats (compiler), P. 1-7.• James F. Dolan, David D. Bowman, and Charles G. Sammis, Data Repository for “Long range and long term fault intersections in southern California”, Supporting data, references, and notes for paleo-earthquakes in the Los Angeles region.

HOW ARE WE “B

LIND” T

O

SOME OF OUR FA

ULTS?

H A N N A H SH A M L O O

BLIND THRUST FAULTSSome faults do not break through the surface anywhere along their

length

http://earthsci.org/processes/struct/equake1/EQCaseHistories.html

PUENTE HILLS THRUST FAULTRecently discovered,

1999

Los Angeles Basin

Runs about 40 km

Three segments

Slip rate 5mm/year

4 Major E.Q.’s last 11,000 years

http://www.scec.org/research/030404dolan.html

DANGER

Compared to Northridge…

Northridge’s E.Q. directed strongest shaking towards N to sparsely populated mountains

PHT fault focuses its shaking toward downtown LA

LA Basin amplifies shaking

15x stronger energy release

Viz Credits: Amit Chourasia 

REFERENCESMarquis, John. "New Study Reveals The Behavior Of The Puente Hills

Thrust Fault." New Study Reveals The Behavior Of The Puente Hills Thrust Fault. Southern California Earthquake Center, 4 Apr. 2003. Web. 18 June 2013.

Maugh II, Thomas H. (May 26, 2005). "Big Fault Under L.A. Could Be Devastating". Los Angeles Times 26 May 2005. Web. 18 Jan. 2013

Shaw, John H., Andreas Plesch, James F. Dolan, Thomas L. Pratt, and Patricia Fore. "Puente Hills Blind-Thrust System, Los Angeles, California." Thesis. N.d. Bulletin of the Seismological Society of America, 16 Nov. 2001. Web. 18 Jan. 2013.

HOW THE 1971 SAN

FERNANDO AND THE 1994

NORTHRIDGE

EARTHQUAKES COMPARE

M I GU E L F

R I AS - R O D R I G

U E Z

COMPARING TWO THE EARTHQUAKES

S A N F E R N A N D O 1 9 7 1 N O R T H R I D G E 1 9 9 4

SAN FERNANDO EARTHQUAKE (1971)

NORTHRIDGE EARTHQUAKE (1994)

REFERENCESAbridged from Seismicity of the United States, 1568-1989 (Revised), by Carl W. Stover and Jerry L. Coffman, U.S. Geological Survey Professional Paper 1527, United States Government Printing Office, Washington: 1993.r earthquake [updated]

Posted By: Scott Harrison Posted On: 12:25 a.m. | February 9, 2011, PHOTOGRAPH BY: BRUCE COX / LOS ANGELES TIMES.

U.S. Department of the Interior | U.S. Geological Survey URL: http://pubs.usgs.gov/of/1996/ofr-96-0263/execsum.htm

Bolt, Bruce A. (1971). The San Fernando Valley, California, Earthquake of February 9, 1971: Data on Seismic Hazards. Bulletin of the Seismological Society of America, Vol. 61, No. 2, pp. 501-510, Figure 2.

R. S. Stein, G. C. P. King and J. Lin, Stress triggering of the 1994 M 6.7 Northridge , California, Earthquake by its Predecessors.

HOW FAULT

FEATURES

ARE EXPRESSED IN

AN

URBAN ENVIRONMENT

M I GU E L V

I LL A S A N A

http://www.artinaid.com/wp-content/uploads/2013/04/Types-of-Faults.jpg

http://la.streetsblog.org/wp-content/uploads/2011/10/source-westside-fault-lines.jpg

REFERENCESNewton, Damien, “Rest In Peace: Santa Monica Blvd. Subway”. Wednesday, Oct 19,2011. Web

Braid, Barbara, “What are the three types of Earthquakes Faults?”, Jan23, 2010. Web

LOS ANGELES, A

CITY OF

FAULTS

M AT T RI E

M A N

Los Angeles: A City of Faults

Faults in Los Angeles

Freeways cross faults in many locations creating potential risk.

Collapse of freeway bridges during the Northridge earthquake caused widespread recognition of the hazard.

Effect on Infrastructure

- Faults run throughout the LA basin Blind thrust faults such as the Puente Hills fault are particularly dangerous-Skyscrapers are not designed for all possible motions and still have the potential to collapse during specific (and uncommon) motions

ANOTHER RESULT OF FAULTINGOil can become trapped along faults

Yet seepage can also occur along faults

Tar pits- Caused by oil seeping up along a fault and degrading to asphalt

Questions?

REFERENCES:405 Traffic. 2012. MNG Interactive. Photograph. Web. 20 Jun 2013. Uuuuuuu

iiiiiiiiiiiiiiiiiii<http://extras.mnginteractive.com/live/media/site200/2012/0615/2012061 5__405_traffic_01.JPG>.

Elle, Alli. Texture 79. Photograph. Deviant Art. Web. 20 Jun 2013. <http://couch-and- uuuuuuucanvas.deviantart.com/art/Texture-79-159359821>.

La Brea Tar Pits March 2010. Photograph. Web. 20 Jun 2013. uuuuuuu<http://www.thegypsiestownsend.com/2011/03/la-brea-tar-pits-march-iiiiiiiiiiiiiiii2010.html>.

Los Angeles Skyline. Photograph. Web. 20 Jun 2013. Uuuuuuu<http://www.thewallpapers.org/photo/17314/los_angeles_skyline-003.jpg>.

Northridge Earthquake. Photograph. Natural Disaster Atlas of the United States. Web. 20 u uuuuuuuJun2013.<http://naturaldisasteratlas.weebly.com/uploads/5/1/2/3/5123992/ 938 6727_orig.jpg>.

Sheibley, Mari. LA at Night. 2012. Photograph. Web. 20 Jun 2013. <http://www.marisheibley.com/post/19185422109/3-11-12-la-at-night>.

Weber, Betsy. La Brea Tar Pits. 2010. Photograph. Flickr. Web. 20 Jun 2013. <http://www.flickr.com/photos/betsyweber/5301040950/>.