THE GREAT CALIFORNIA SHAKEOUT Sheila Bart, Greg Berger, Georgina Campos, Garland Chen, Jaquelyn Felix, Brandon Green

W HY IS C ALIFORNIA REFERRED TO AS “ EARTHQUAKE COUNTRY ”?

The frequency of earthquakes in California - On average, there are approximately 30 earthquakes each day in California. - Earthquakes of magnitude 6.0 and greater occur approximately every 5 years. - In comparison to the central and eastern sections of the United States, California experiences a greater amount of seismicity.

Fault systems throughout California - The San Andreas Fault system extends from northern California and continues south past the California border and into Mexico. - In addition to the San Andreas Fault system, there are a number of other smaller fault systems throughout the state of California. - The Los Angeles area itself has a number of faults that contribute to both small and relatively large earthquakes.

Works Cited ❏ ❏ Jones, L., Benthien, M. “Putting down roots in earthquake country”. Southern California Earthquake Center ontents.html ❏ Southern California Earthquake Data Center

W HAT TYPE OF FAULTS EXIST IN C ALIFORNIA ? The answer may surprise you…

Normal Faults What is it?Where is it?  Caused by extension  Outward displacement  Death Valley Horst and Graben Elevation: -282 ft

Reverse Faults What is it?Where is it?  Caused by compression  Inward displacement  Transverse Ranges

Strike-Slip Faults What is it?Where is it?  Displacement is parallel to fault strike  San Andreas Fault

Oblique Faults  A combination of strike-slip and reverse thrusting  The most common type of fault What is it?

Works Cited  Bartolomeo, Eleanor, and Nicole Longinotti. "Tectonic history of the Transverse Ranges: Rotation and deformation on the plate boundary.". UC Davis, n.d. Web. 19 June  Johnson, Jenda. "What are the 4 basic classes of faults?" Incorporated Research Institutions for Seismology. Web. 17 June  Jordan, Tom, Raymon Siever, and John Grotzinger. "Folds, Faults, and Other Records of Rock Deformation." Understanding Earth. New York: Frank Press, Print.  "Lowest Places on Earth." Death Valley. National Park Service. Web. 17 June  "The San Andreas Fault." USGS. 17 January Web. 17 June

PLATE BOUNDARIES IN CALIFORNIA

Plate Composition  7 km (4 mi) thick  Basalt  More dense  Varies between 10 and 75 km (6 and 47mi)  Granitic rock  Less dense OceanicContinental

Plate Boundaries  Two plates move apart in opposite directions  Think: conveyor belts  Magma flows up from the mantle where plates thin  Mid-ocean ridges DivergentConvergent  Plates pushing into each other  Continental → Continental  Continental → Oceanic  Oceanic → Oceanic  DENSITY  Mountain formation  Subduction

What kind of plate boundaries are found in California?  San Andreas fault zone → Transform Boundary  Pacific plate moves Northwest in relation to NA plate  Great 1906 earthquake that destroyed San Francisco Transform  Horizontal motion past each other  Mostly slide without creating or destroying material  Large earthquakes can occur at transform plate boundaries

Works Cited  Press, F., Siever, R., Grotzinger, J., Jordan, T. H., 2003, Understanding Earth  “Understanding Plate Motions.” United States Geological Survey: dynamic/ understanding.html, May

Explain how focal mechanisms can be determined from earthquake data?

What are focal mechanisms?

How are they calculated?

What does this all mean? Faulting geometry identification Look they’re beach balls!

compression vs. dilatation

Works Cited Cronin, Vince, 2004, A Draft Pimer on Focal Mechanism Solution for Geologists, p USGS, “Focal Mechanisms.” Learn: Earthquake topics for Education.. IRIS, “Focal Mechanisms Explained.”. Merriam-Webster, “the Dictionary.” California Institute of Technology, “San Jacinto Fault Zone.” Springer Link, “Earthquake, Focal Mechanism.” openSHA, “Strike, Dip, and Rake (focal Mechanism).” Calvin College. “Eachquakes: A World in Motion. Recent Quakes, Calvin Seismograph…”

What is a Major Earthquake? Magnitude Intensity Richter Magnitude Moment Magnitude measures the energy released at the source of the earthquake and it is determined from measurements on seismographs. takes the amplitude and distances of seismograms and is known to underestimate the size of large quakes. measures the strength of shaking produced by the earthquake at a certain location and it is evaluated from effects on people, human structures, and the natural environment. Magnitude is related to the physical parameters that uses seismic moment (Mo), the force needed to generate the recorded waves, determines the energy released by the quake. M W = 2/3 log10(M O )

What is a Major Earthquake?

San Francisco Earthquake :12 AM - April 18, 1906 Magnitude: 7.8 Intensity: maximum intensity of XI was based on geologic effects, but the highest intensity based on damage was IX. Rupturing about 430 km or more to the northernmost of the San Andreas Fault The earthquake was felt from southern Oregon to south of Los Angeles and inland as far as central Nevada. Due to water pipe breakage, the water was shut off. Since there was no water, the fire got set off causing a large part of San Francisco to burn down.

Major Earthquakes since 1906 DateEarthquakeMagnitudeFaults 18 April 1906 San FranciscoM L 7.8San Andreas 4 Nov Offshore Lompoc M L 7.1Hosgri 21 July 1952 Kern CountyM w 7.5White Wolf 28 June 1992 LandersM w 7.3Johnson Valley, Kickapoo, Homestead Valley, Emerson, and Camp Rock 18 Oct Hector MineM w 7.1Hector Mine (Lavic Lake) and Bullion (Pisgah)

Faults Involved... Type of FaultEarthquake Fault Names Right-Lateral Strike Slip Landers Johnson Valley, Landers, Homestead Valley, Emerson, and Camp Rock faults Hector Mine Lavic Lake and Bullion Reverse with some Left-Lateral Kern CountyWhite Wolf Reverse and ThrustLompoc Hosgri

Works Cited “Historical Earthquakes: San Francisco 1906.” USGS: Earthquake Hazards Program. 1 November Web. 16 June “Hector Mine Earthquake.” Southern California Earthquake Data Center. Caltech, 31 January Web. 16 June “Kern County Earthquake.” Southern California Earthquake Data Center. Caltech, 31 January Web. 16 June “Lompoc Earthquake.” Southern California Earthquake Data Center. Caltech, 31 January Web. 16 June “Landers Earthquake.” Southern California Earthquake Data Center. Caltech, 31 January Web. 16 June “Measuring the Size of an Earthquake.” USGS: Earthquake Hazards Program. 1 November Web. 16 June Zoback, Mary Lou. “The 1906 Earthquake and a Century of Progress in Understanding Earthquakes and their Hazards.” GSA Today April/May. 2006: Print.

What is “Drop, Cover and Hold on” and who is participating?

ShakeOut: “Drop, Cover, and Hold On.”  11 million participants (US & other countries)  7,200,000 from California  830,000 from Japan  Who is Participating?  K-12 School Districts  Colleges and Universities  Businesses  Government Institutions

What is “Drop, Cover, and Hold on?”  Actions to take during an earthquake:  DROP to the ground  COVER by getting under a sturdy desk or table  HOLD ON to it until the shaking stops

Works Cited  Shakeout – Drop, Cover, and Hold On: