Earthquakes I-880, Oakland, CA (October 1989).

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Presentation transcript:

Earthquakes I-880, Oakland, CA (October 1989)

Magnitude 5+ earthquakes 1980 - 1990

Earthquake Formation Earthquakes occur when rock’s under stress shift along a fault.

Elastic rebound theory states that rocks under stress will strain and then “rebound” back after plates slide past each other. (this causes earthquake and possibly tsunami’s)

Earthquake focus and epicenter Focus: area where fault slip occurred. Epicenter: point on earth’s surface above focus.

Finish Earth’s Deadliest Earthquakes

Earthquake Basics What is an Earthquake? Causes of Earthquakes Elastic Rebound Theory How are earthquakes measured? Seismometers/Seismographs

Types of Earthquake Waves P (primary) waves Compressional (push-pull) Fastest waves (first to arrive at seismograph) Move through all materials

Evidence of P-wave motion

Types of Earthquake Waves S (secondary) waves Move perpendicular to P wave Second fastest waves (next to arrive at seismograph) Move ONLY through solids

Types of Earthquake Waves Surface waves Rolling motion Slowest waves (arrive last at seismograph) Cause most damage

Seismometer

A seismogram records wave amplitude vs. time

Locating an Epicenter View Seismograms Measure P and S wave arrivals

P S

Locating an Epicenter View Seismograms Measure P and S wave arrivals Measure S-wave “lag” time ( = S - P) Use Travel-Time graph to correlate distance.

Locating an Epicenter View Seismograms Measure P and S wave arrivals Measure S-wave “lag” time ( = S - P) Use Travel-Time graph to correlate distance. Triangulate Distances

PRACTICE TIME!!

Seismogram

http://seismo.berkeley.edu/seismo/faq/iup/eq_local.html

Shadow Zone P-waves reflect between 0-104 P-waves refract between 104-150 S-waves only reflect Proves outer core is LIQUID!

Measuring Strength Earthquake Magnitude Charles Richter designed first scale Based on height of the largest seismic wave Every 1 increase in magnitude = 10x increase in strength

Earthquake Damage: Liquifaction

Earthquake Damage: Liquifaction

Earthquake Damage: Liquifaction

Tsunami Formation

Tsunami travel time (hours; simulation) NOAA

Dec. 2004 Sumatra Tsunami http://staff.aist.go.jp/kenji.satake/animation.gif

Current Seismic Events Earthquakes http://earthquake.usgs.gov/recenteqs/ Tsunami http://wcatwc.arh.noaa.gov/tsunami.htm

References Used http://science.howstuffworks.com/earthquake6.htm http://www.data.scec.org/chrono_index/bigbear.html http://pubs.usgs.gov/dds/dds-29/web_pages/los_gatos.html http://earthquake.usgs.gov/bytopic/photos.html http://earthquake.usgs.gov/4teachers/ http://earthquake.usgs.gov/recenteqs/