Earthquakes USGS Earthquake Hazards Program Earthquake Basics But maybe some that you haven’t already learned and some great pictures to go with it Overview: Global perspective Plate tectonics Faults Real-life examples of faults Fault rupture movie Earthquake shaking and effects Seismic waves, magnitude and location Faults and earthquakes in our local area earthquake info on the web U.S. Department of the Interior U.S. Geological Survey

Bellwork Explain the relationship between stress and strain. Describe what happens when the stress applied to a rock exceeds the strength of the material. Illustrate the three major types of boundaries and what geologic feature is found at each.

Plate Boundaries Three types of interactions between plates as they move around: Sliding past one another - transform boundary Running into one another - convergent boundary Moving away from one another - divergent boundary

Plate Tectonics Lisa Wald USGS Earthquake Hazards Program USGS Pasadena Pattern of earthquakes defines the boundaries of tectonic plates About 23 major plates Can you see where we are? Boundary between two plates We’ll come back to this later U.S. Department of the Interior U.S. Geological Survey

Global Distribution of Earthquakes Map of world Dots are earthquakes Not scattered all over the world, but make a pattern

Pacific-North American Plate Boundary LA on Pacific Plate San Francisco on North American Plate San Andreas Fault is boundary Relative motion Takes Big Bend above LA area and causes compression in our area

The San Andreas Fault

Three Types of Faults Strike-Slip Reverse Normal Three types of faults Form depending on type of plate motion and complex reaction of earth’s lithospheric blocks Strike-slip Normal Thrust Normal

Strike-slip Fault Example Strike-slip example moletrack

Strike-slip Fault Example Before earthquake manure pile was under window where farmer shoveled it out from inside Fault runs right under corner of barn After earthquake manure pile moved over about 10 feet 1906 San Francisco Earthquake

Normal Fault Example Dixie Valley-Fairview Peaks, Nevada earthquake December 16, 1954

Reverse Fault Example

Is there such a thing as “Earthquake Weather”??? No!

Bigger Faults Make Bigger Earthquakes Y axis is length of fault X axis is magnitude of earthquake

Bigger Earthquakes Last a Longer Time Y axis is how many seconds the earthquake lasts X axis is the magnitude of the earthquake

Questions to think about while viewing: View EQ Damage http://www.youtube.com/watch?v=dLWN7AHftBo&feature=related http://www.youtube.com/watch?v=_KtxCcS7NNw&feature=related Questions to think about while viewing: What is released when an EQ occurs? Where does this energy go? How do we record the information about this energy?

What are seismic waves? http://bex.mtholyoke.edu/animation/3/

What are the differences in these waves? Which wave will arrive at a location first? Do the waves leave the EQ focus at different times? Describe the speed of the two waves. Are these waves found on the surface of the Earth or the interior?

Seismic Waves

Primary Wave - Fast wave!

Secondary Waves Can only travel through solid material

Long Wave (or L wave) - Converted S & P wave energy - Slowest wave

Summary Secondary waves do not travel through liquids, only solids Primary waves arrive first, followed by Secondary waves. Seismologists know how fast seismic waves travel, and this helps locate earthquakes.

Earthquake Effects - Ground Shaking Northridge earthquake 1994 Parking garage at Cal State Northridge Northridge, CA 1994

Earthquake Effects - Ground Shaking Northridge, CA 1994

Earthquake Effects - Ground Shaking Loma Prieta, CA 1989 KGO-TV News ABC-7

Earthquake Effects - Ground Shaking Kobe, Japan 1995

Earthquake Effects - Ground Shaking Kobe, Japan 1995

Earthquake Effects - Surface Faulting Landers, CA 1992

Earthquake Effects - Liquefaction Source: National Geophysical Data Center Niigata, Japan 1964

Earthquake Effects - Landslides Source: National Geophysical Data Center Turnnagin Heights,Alaska,1964

Earthquake Effects - Fires Loma Prieta, CA 1989 KGO-TV News ABC-7

Earthquake Effects - Tsunamis 1957 Aleutian Tsunami Photograph Credit: Henry Helbush. Source: National Geophysical Data Center

Lag Time!

Earthquake Location

Locating an EQ epicenter

Earthquake Magnitude M5 M6 M7

Scales to measure Earthquakes Richter Scale Modified Mercalli Scale Moment Magnitude Scale

An Earthquake has occurred! USGS needs YOUR help to determine where it has taken place. One seismic station in Detroit, MI has reported that the EQ epicenter is 15 km from their station.

An Earthquake has occurred! Can we locate the EQ epicenter? Why or why not? Do we have anything to work with to determine where the EQ was located? What should we do?

An Earthquake has occurred! Another seismic station in Charleston, SC has reported that the EQ epicenter is 65 km from their station.

An Earthquake has occurred! Can we locate the EQ epicenter? Why or why not? Are we any closer to determining this? What do we still need?

An Earthquake has occurred! A third seismic station in Minneapolis, MN has reported that the EQ epicenter is 48 km from their station.

Can we locate this earthquake?? YES!!

Will California eventually fall into the ocean??? No!

Faults of Southern California San Andreas Fault in red Point out other major faults Source: SCEC Data Center

Shaking Hazard in Southern California

Faults in Our Local Area - Arcadia Sierra Madre Fault Zone THRUST fault 55 KM long Last ruptured in last 10,000 YEARS SLIP RATE: between 0.36 and 4 mm/yr PROBABLE MAGNITUDES: MW6.0 - 7.0 (?) Dips to the north Source: SCEC Data Center

Faults in Our Local Area - Arcadia Raymond Fault STRIKE-SLIP fault 26 KM long Last ruptured in last 10,000 YEARS SLIP RATE: between 0.10 and 0.22 mm/yr Source: SCEC Data Center PROBABLE MAGNITUDES: MW6.0 - 7.0 Dips to the north At least eight surface-rupturing events have occurred along this fault in the last 36,000 years

Faults in Our Local Area - Arcadia Clamshell-Sawpit Canyon fault THRUST fault 18 KM long Last ruptured in last 1.6 million YEARS SLIP RATE: ??? PROBABLE MAGNITUDES: ??? Dips to the north Source: SCEC Data Center

Real-time Earthquake Information Can’t predict earthquakes But we can tell you a lot about one that just happened Within minutes after it happened All info on the web. Plot from last Thursday How many earthquakes happen each day in CA? ~60

ShakeMaps

Did You Feel It? Community Internet Intensity Maps

The End Where to go for more information: http://pasadena.wr.usgs.gov/ USGS Earthquake Hazards Program U.S. Department of the Interior U.S. Geological Survey Where to go for more information: http://pasadena.wr.usgs.gov/ http://earthquake.usgs.gov/ The End

Faults in Our Local Area - La Canada TYPE OF FAULTING: reverse LENGTH: the zone is about 55 km long; total length of main fault segments is about 75 km, with each segment measuring roughly 15 km long MOST RECENT SURFACE RUPTURE: Holocene, 10,000 years to present SLIP RATE: between 0.36 and 4 mm/yr INTERVAL BETWEEN SURFACE RUPTURES: several thousand years (?) PROBABLE MAGNITUDES: MW6.0 - 7.0 (?) OTHER NOTES: This fault zone dips to the north. Source: SCEC Data Center