Download Plate Boundaries in California

THE GREAT
CALIFORNIA
SHAKEOUT
Sheila Bart, Greg Berger, Georgina Campos, Garland Chen, Jaquelyn Felix, Brandon Green
WHY IS CALIFORNIA
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
❏<earthquake.usgs.gov/earthquakes/st
ates/seismicity>
❏Jones, L., Benthien, M. “Putting down
roots in earthquake country”. Southern
California Earthquake Center. 2011.
<www.earthquakecountry.info/roots/c
ontents.html>
❏Southern California Earthquake Data
Center
<www.data.scec.org/index.html>
WHAT TYPE OF FAULTS EXIST IN CALIFORNIA?
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
What is it?
◻ A combination of strike-slip and reverse thrusting
◻ The most common type of fault
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 2014.
◻ Johnson, Jenda. "What are the 4 basic classes of faults?" Incorporated Research
Institutions for Seismology. Web. 17 June 2014.
http://www.iris.edu/hq/programs/education_and_outreach/animations/2.
◻ Jordan, Tom, Raymon Siever, and John Grotzinger. "Folds, Faults, and Other
Records of Rock Deformation." Understanding Earth. New York: Frank Press, 2003.
Print.
◻ "Lowest Places on Earth." Death Valley. National Park Service. Web. 17 June 2014.
◻ "The San Andreas Fault." USGS. 17 January 2013. Web. 17 June 2014.
http://pubs.usgs.gov/gip/earthq3/safaultgip.html.
PLATE BOUNDARIES IN
CALIFORNIA
Plate Composition
Oceanic

7 km (4 mi) thick

Basalt

More dense
Continental



Varies between 10 and 75 km (6
and 47mi)
Granitic rock
Less dense
Plate Boundaries
Convergent

Plates pushing into each
other

Continental → Continental

Continental → Oceanic

Oceanic → Oceanic

DENSITY

Mountain formation

Subduction
Divergent




Two plates move apart in
opposite directions
Think: conveyor belts
Magma flows up from the
mantle where plates thin
Mid-ocean ridges
What kind of plate boundaries are
found in California?
Transform



Horizontal motion past each other
Mostly slide without creating or
destroying material
Large earthquakes can occur at
transform plate boundaries
 San Andreas fault zone →
Transform Boundary
 Pacific plate moves Northwest in
relation to NA plate
 Great 1906 earthquake that
destroyed San Francisco
Works Cited


Press, F., Siever, R., Grotzinger, J., Jordan, T. H.,
2003, Understanding Earth
“Understanding Plate Motions.” United States
Geological Survey: http://pubs.usgs.gov/gip/
dynamic/ understanding.html, May 2012.
Explain how
focal mechanisms
can be determined from
earthquake data?
What are focal mechanisms?
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. 1-14
USGS, 1996. “Focal Mechanisms.” Learn: Earthquake topics for Education.
<http://earthquake.usgs.gov/learn/topics/beachball.php>.
IRIS, 2012. “Focal Mechanisms Explained.” <http://www.youtube.com/watch?v=MomVOkyDdLo>.
Merriam-Webster, 2014. “the Dictionary.”
<http://www.merriam-webster.com/dictionary/dilatation>
California Institute of Technology, 2014. “San Jacinto Fault Zone.”
<http://www.data.scec.org/significant/sanjacinto.html>
Springer Link, 2011. “Earthquake, Focal Mechanism.”
<http://link.springer.com/referenceworkentry/10.1007%2F978-90-481-8702-7_158/fulltext.html>
openSHA, 1980. “Strike, Dip, and Rake (focal Mechanism).”
<http://www.opensha.org/glossary-strikeDipRake>
Calvin College. “Eachquakes: A World in Motion. Recent Quakes, Calvin Seismograph…”
<http://www.calvin.edu/academic/geology/seismology/>
What is a Major Earthquake?
Magnitude
Intensity
measures the energy released at the
source of the earthquake and it is
determined from measurements on
seismographs.
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.
Richter Magnitude
Moment Magnitude
takes the amplitude and distances
of seismograms and is known to
underestimate the size of large
quakes.
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. MW = 2/3 log10(MO) - 10.7
What is a Major Earthquake?
San Francisco Earthquake 1906
5:12 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
Date
Earthquake
Magnitude
Faults
18 April
1906
San Francisco
ML 7.8
San Andreas
4 Nov.
1927
Offshore
Lompoc
ML 7.1
Hosgri
21 July
1952
Kern County
Mw 7.5
White Wolf
28 June
1992
Landers
Mw 7.3
Johnson
Valley,
Kickapoo,
Homestead
Valley,
Emerson, and
Camp Rock
18 Oct.
1999
Hector Mine
Mw 7.1
Hector Mine
(Lavic Lake)
and Bullion
(Pisgah)
Faults Involved . . .
Type of Fault
Earthquake
Fault Names
Landers
Johnson Valley,
Landers, Homestead
Valley, Emerson, and
Camp Rock faults
Hector Mine
Lavic Lake and
Bullion
Kern County
White Wolf
Right-Lateral Strike
Slip
Reverse with some
Left-Lateral
Hosgri
Reverse and Thrust
Lompoc
Works Cited
“Historical Earthquakes: San Francisco 1906.” USGS: Earthquake Hazards Program. 1 November 2012. Web.
16 June 2014. <http://earthquake.usgs.gov/earthquakes/states/events/1906_04_18.php>.
“Hector Mine Earthquake.” Southern California Earthquake Data Center. Caltech, 31 January 2013. Web.
16 June 2014. <http://www.data.scec.org/significant/hectormine1999.html>.
“Kern County Earthquake.” Southern California Earthquake Data Center. Caltech, 31 January 2013. Web.
16 June 2014. <http://www.data.scec.org/significant/kern1952.html>.
“Lompoc Earthquake.” Southern California Earthquake Data Center. Caltech, 31 January 2013. Web.
16 June 2014. <http://www.data.scec.org/significant/lompoc1927.html>.
“Landers Earthquake.” Southern California Earthquake Data Center. Caltech, 31 January 2013. Web.
16 June 2014. <http://www.data.scec.org/significant/landers1992.html>.
“Measuring the Size of an Earthquake.” USGS: Earthquake Hazards Program. 1 November 2012. Web.
16 June 2014. <http://earthquake.usgs.gov/learn/topics/measure.php>.
Zoback, Mary Lou. “The 1906 Earthquake and a Century of Progress in Understanding Earthquakes and
their Hazards.” GSA Today April/May. 2006: 1-11. 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:
http://www.shakeout.org/dropcoverholdon/