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Faults of Los Angeles Team 3: Ernest Scapini Luis Gomez

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1 Faults of Los Angeles Team 3: Ernest Scapini Luis Gomez
Alicia Sellsted Elena Pierce Paulo Dos Santos Francisco Raygoza SCEC UseIT

2 Los Angeles: The City of Faults
Ernest Scapini

3 Faults in Los Angeles There is a total of 16 faults in Los Angeles
Los Angeles is composed of Reverse, Right lateral, and left lateral faults They are 7 faults in Los angeles capable of creating a Magnitude 7 earthquake

4 Significant Faults in Los Angeles
Puente Hills Fault Compton Thrust Fault Newport-Inglewood Fault Raymond Fault Northridge Thrust Fault Santa Susana Fault Sierra Madre Fault Zone Hollywood Fault

5 Northridge Thrust TYPE OF FAULTING: Blind Thrust TIME: January 17, 1994 / 4:30:55 am PST MAGNITUDE: MW6.7 Damage: 40,000 buildings were damaged in Los Angeles, Ventura, Orange, and San Bernardino Counties LOCATION: 34° 12.80' N, 118° 32.22' W 20 miles west-northwest of Los Angeles 1 mile south-southwest of Northridge  Depth: 18.4 km Deaths: 57 Northridge Thrust Shake Map

6 Palos Verde Fault Largest fault in Los Angeles
Type of Fault: Right Lateral Reverse Length: Roughly 80 km Probable Magnitude: MW ( could be greater) It may rupture partially due to the geometry of the fault. Slip Rate: between 0.1 and 3.0 mm/year Los Angeles Port is close to the fault Palos Verde Fault

7 Puente Hills Faults Type: Blind Thrust Largest probable magnitude
Was discovered in 1999 USC is right above the Puente Hills fault Length: 40 km Probable Magnitude: MW Puente Hills Faults

8 Compton Thrust Type: Blind Thrust Slip Rate: 1.4 ± 0.4 mm/year
Probable Magnitude: MW 7.0 – 7.4 LAX will be greatly impacted by this fault Displacement can be from 1.3 to 4.2 m Length: 60 km Has had 6 large earthquakes in the past 14,000 years Compton Thrust

9 Work Cited Dolan, J.F., Sieh, K., and Rockwell, T.K., 2000a, Late Quaternary activity and seismic potential of the Santa Monica fault system, Los Angeles, California: Geol. Soc. America Bull. 112: *Dolan F. James, 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. Yeat Dewell, Henry D. and Willis, Bailey (1925). Earthquake Damage to Buildings. Bulletin of the Seismological Society of America, Vol. 15, No. 4, pp , Plates 31b and 42a. Leon, L. A., J. F. Dolan, J. H. Shaw, and T. L. Pratt (2009), Evidence for large Holocene earthquakes on the Compton thrust fault, Los Angeles, California, J. Geophys. Res., 114, B12305, doi: /2008JB Marquis John “New Study Reveals the Behavior of the Puente Hills Thrust Fault” USC News April 4, Web 19 Jun. 2014 Shaw H. John, Suppe John 1996 “Earthquake hazards of active blind-thrust faults under the central Los Angeles basin, California” Journal of Geophysical Research vol 101 p

10 Los Angeles Basin Luis Gomez

11 “Earthquakes don't kill people, buildings do”
Why areas within the “Sedimentary” L.A. basin are more dangerous in earthquakes than areas in the surrounding mountains (San Gabriel, Santa Monica, Santa Ana mountains..)? “Earthquakes don't kill people, buildings do” - Susan Hough and Lucile Jones Luis Gomez

12 “Sedimentary” Los Angeles Basin
The Center of Los Angeles basin at ° N, ° W (Intersection of 105 and 710 FWY) - Deepest spot of basin, ≈ 10 km (6 mi) Giant Bowl feature has walls consisting of San Gabriel, Santa Monica, Santa Ana mountains, and the Palos Verdes Peninsula “Bowl of sediment” amplifies the motion of an earthquake in unpredictable ways, somewhat similar to shaking a bowl of Jello

13 Los Angeles Basin Basin primarily consists of sand, clay, and silt
≈81 km (50mi) long ≈40 km (25mi) wide

14 Basin Walls The Palos Verdes Peninsula and mountain ranges line the Los Angeles basin Shaking from an earthquake in the basin could be 5 or more times intense than in the nearby mountains

15 Puente Hills Earthquake Simulation
2 sec sec sec sec sec sec. 20 sec sec sec sec.

16 References "Earthquake Shaking - Putting Down Roots in Earthquake Country." Earthquake Shaking - Putting Down Roots in Earthquake Country. Southern California Earthquake Center/ USGS/ FEMA/ Cal EMA, Web. 13 June 2014. "The Los Angeles Basin - A Huge Bowl of Sand." The Los Angeles Basin - A Huge Bowl of Sand. The Los Angeles Almanac, n.d. Web. 13 June <http://www.laalmanac.com/geography/ge08e.htm>. "Movie: Instantaneous Peak Velocity." SDSC, n.d. Web. 13 June 2014. Nelson, Stephen A. "EQ Hazards & Risks." EQ Hazards & Risks. N.p., 28 Aug Web. 17 June 2014.

17 The Santa Monica, Hollywood, and Raymond Faults
Alicia Sellsted

18 Santa Monica Fault Oblique left-reverse fault 24 km in length
Slip rate ranges from mm per year

19 Hollywood Fault Left-lateral strike slip fault 14-15 km in length
Slip rate ranges from mm per year 4.1

20 Raymond Fault Reverse-left-oblique slip fault 25-26 km in length
Slip rate ranges from mm per year

21 Hollywood and Santa Monica Faults
“Hollywood fault has not been officially mapped, even though the state has known of its existence for decades.” -LA Times Many buildings have been built on top of these faults because without official state maps the city isn’t required to follow state law.

22 All three faults are part of the Southern Transverse Ranges fault system. These faults could act co-seismically in an earthquake of magnitude 7 or above because of their proximity to each other. 4.2

23 References “3.2 Earthquake Hits Hollywood Fault – UPDATE: New 3.4 quake.” Save Hollywood. 4 September Web. “Hollywood Fault.” Southern California Earthquake Data Center. 31 January Caltech. Web: “Raymond Fault.” Southern California Earthquake Data Center. 31 January Caltech. Web: “Santa Monica Fault.” Southern California Earthquake Data Center. 31 January Caltech. Web: Dolan, James, “Faults of Los Angeles.” Southern California Earthquake Center: Lin II, Rong-Gong, Xia, Rosanna, Smith, Doug. 2013, “Campaign to map earthquake faults has slowed to a crawl.” Los Angeles Times:

24 Blind Thrust Faults Elena Pierce

25 Blind Thrust Faults Basics
- A thrust fault that does not rupture all the way to the surface, no evidence on the ground “blind” - May create ridges or anticlines (Fold Belts) - Buried under uppermost layer of rock 5.2

26 Northridge Blind Thrust Fault
Date: January 17, Time: 4:30 am Magnitude: Depth: 18.4 km Killed 57 people $20 Billion in Damage (SCEDC and CNN News) 5.3

27 Impact if Northridge After the earthquake technology began to advance
NASA led agencies towards creating 250 new GPS stations (CNN) 5.4

28 Puente Hills Blind Thrust Fault
- Extends from Northern Orange County to San Gabriel, runs under Downtown to Los Angeles - 11 X greater movement in Sedimentary Basin - Duration said to be 4X longer because energy flows through sediment faster - Dense population makes earthquake damage potential much higher (NBC, LA Times) 5.5

29 Compton Blind Thrust Fault
- average slip rate of 1.4 +/-0.4 mm/ year - active fault in sedimentary basin - found through displacements in the earth - can harm the Los Angeles area

30 References II, Rong-Gong Lin. "La Habra Quake a Reminder about Dangerous Puente Hills Fault." Los Angeles Times. Los Angeles Times, 29 Mar Web. 13 June 2014. Moore, Ireene. "Experts Warn of Dangers on Puente Hills Fault." NBC Southern California. NBC, 1 Apr Web. 13 June 2014. "Significant Earthquakes and Faults." Southern California Earthquake Data Center at Caltech. SCEDC, n.d. Web. 10 June 2014.

31 The San Gabriel Mountains
Paulo Dos Santos

32 How the San Gabriel Mountains were uplifted
Transverse Ranges SAF Big Bend Movement of the Plates Pacific Plate North American Plate SCEC UseIT Intern Paulo Henrique Dos Santos

33 How the San Gabriel Mountains were uplifted
Fault Zones San Andreas San Gabriel Sierra Madre Cucamonga SCEC UseIT Intern Paulo Henrique Dos Santos

34 How the San Gabriel Mountains were uplifted
Transform Faults Strike-slip Reverse Faults Thrust Faults (less than 45°) SCEC UseIT Intern Paulo Henrique Dos Santos

35 Work Cited "California Coast Ranges." Wikipedia. Wikimedia Foundation, 06 Mar Web. 16 June <http://en.wikipedia.org/wiki/California_Coast_Ranges> Fei, Yongxin. "Formation of the San Gabriel Mountains." Formation of the San Gabriel Mountains. N.p., n.d. Web. 16 June <http://scec.usc.edu/internships/useit/scec-vdo/animation874> "Geology of the San Gabriel Mountains." Geology of the San Gabriel Mountains. N.p., n.d. Web. 16 June <http://www.csun.edu/science/geoscience/fieldtrips/san-gabriel-mts/geology-san-gabriels.html> "Humboldt County, California." Wikipedia. Wikimedia Foundation, 16 June Web. 16 June <http://en.wikipedia.org/wiki/Humboldt_County,_California> "Transverse Range." Wikipedia. Wikimedia Foundation, 22 Apr Web. 16 June <http://en.wikipedia.org/wiki/Transverse_Range> McClay, K. R. Thrust Tectonics. London: Chapman & Hall, Web. <http://ocw.mit.edu/courses/earth-atmospheric-and-planetary-sciences/ structural-geology-fall-2005/lecture-notes/part4_thrst_tect.pdf> Structural Geology Lab – Week 1, and Attitudes Of Lines And Planes In 3.Structural Geology Lab – Week 1 Attitudes of Lines and Planes in 3-D(n.d.): n. pag. Web. <https://www.wou.edu/las/physci/taylor/es406_structure/RD_chap9lab_Faults.pdf> SCEC Team 3 - Question 6 - UseIT Intern Paulo Henrique Dos Santos

36 The San Fernando and Northridge Earthquakes
Francisco Raygoza

37 1971 San Fernando Earthquake
Magnitude 6.6 occurred on 2/9/1971 at 6AM The hypocenter was located at a depth of km Losses 58 deaths Over 500 million dollars in damages First major earthquake to be well studied, greatly influenced structural engineering advancement

38 1971 San Fernando Earthquake
The Earthquake occurred in the San Fernando Fault Zone On the Santa Susana Fault (maybe) The fault has an average slant angle of 45 degrees dipping beneath the San Gabriel Mtns Land movement included strike-slip and over-thrust motion surface displacements up to 1 meter The northern block in which the San Gabriel Mtns lie rose an average of 1 meter around 1.8 meters shortening across Sylmar Fault trace

39 1994 Northridge Earthquake
Magnitude 6.7 on 1/17/1994 at 4:31AM. Most damaging earthquake since the 1906 earthquake Rupture began at a depth of 19 km and ended about 8 km below the surface It was preceded by 2 clusters of foreshocks Loss 60 deaths 7,000 injured 40,000 buildings damaged Over 20 Billion dollars

40 1994 Northridge Earthquake
Northridge thrust fault blind thrust part that many consider part of the the Oak Ridge Thrust fault south-dipping fault below the San Fernando Valley Rupture resulted from a fault movement of about two meters Strong shaking above 1.0g felt in the surrounding area Only physical evidence of is ground deformation with some uplift of the Santa Susana Mountains

41

42 What is the Relationship Between the Two Earthquakes?
Earthquakes occurred on faults belonging to a complex system caused by compressional forces due to the Big Bend of the San Andreas Fault If we consider the Northridge thrust fault part of the Oak Ridge Thrust fault then geographically we can see the earthquake hazard in the occurrence of an earthquake

43 References Staff, (1971), The San Fernando Earthquake-- One of the Most Important, Engineering and Science, 34, p. 4-15 Hauksson, Egill, (1994), The Northridge Earthquake and the “Earthquake Deficit”, Engineering and Science, 57 (4), p (2004), The Northridge, California Earthquake, Risk Management Solutions Hough, S., 2004, Finding Fault in California, Mountain Press Publishing Company, p


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