Introduction to Earthquakes Terms with definitions in red font are suggestions for student note-taking.

25 years of earthquakes: Where do earthquakes occur? Map of earthquakes worldwide over a 25 year period contained in the noted seismicity catalogs. Source: http://denali.gsfc.nasa.gov/dtam/data/ftp/global_all.gif Talking points: What is the map showing? How do earthquake locations relate to plate tectonic boundaries? Are there regions where students are surprised to see lots of earthquakes and did not previously realize were regions of high seismic activity?

Map of tectonic plate boundaries Map of plate boundaries. Compare with previous earthquake map and note that the earthquake locations match up with plate boundaries. Source: http://denali.gsfc.nasa.gov/dtam/data/ftp/gtam.gif

Where do earthquakes tend to occur? Earthquakes can occur anywhere, but they tend to occur on and near tectonic plate boundaries. Emphasize that most earthquakes occur on or near tectonic plate boundaries, but that they can happen anywhere.

What is seismology? Seismology: a science that deals with earthquakes and with artificially produced vibrations of Earth Question for students: What do they think is included in seismology? Additional talking points: Seismology is not just the study of earthquakes. It also includes artificially produced motion of Earth (as well as using motion from earthquakes) to learn about the interior of Earth.

1906 San Francisco Earthquake M 7.7 to M7.9? ~300 miles long! shaking lasted ~1 minute felt from southern Oregon to central Nevada, and south of Los Angeles (maybe in SD?) The 1906 San Francisco earthquake ruptured the portion of the San Andreas Fault from south of San Francisco up to the northern end of the fault. This earthquake was widely felt and caused significant damage within the city of San Francisco. For comparison, the M 6.9 Loma Prieta (1989) earthquake is shown in blue. Loma Prieta caused significant damage, including the collapse of the upper part of the Bay Bridge. http://earthquake.usgs.gov/regional/nca/1906/18april/howlong.php

Massive fires followed the earthquake and burned for several days 1906 San Francisco Earthquake M 7.7 to M7.9? http://www.sfmuseum.org/hist/pix49.html Massive fires followed the earthquake and burned for several days Movie footage of the aftermath can be downloaded from the SF Virtual Museum at http://www.sfmuseum.org/loc/movie.html

1906 San Francisco Earthquake M 7.7 to M7.9? Casualties and Damage Casualties 3000+ People left homeless 225,000 Buildings destroyed 28,000

1994 Northridge (Los Angeles), CA M 6.7 Earthquake Figures are from: http://www.smate.wwu.edu/teched/geology/GeoHaz/eq-CA-Northridge1/eq-CA-Northridge2-05.JPG http://www.jpl.nasa.gov/images/earth/earthquake/earthquake_browse.jpg http://ntl.bts.gov/lib/jpodocs/repts_te/13775_files/image004.jpg Parking structure at Cal Sate Northridge Damage to a hospital Freeway damage

1994 Northridge, CA Earthquake M 6.7 72 people killed 9000 people injured $20 Billion damage Damage up to 85 miles away Severe freeway damage (I-10 and I-5) Structural damage resulted in 11 closed hospitals Figures from: http://pubs.usgs.gov/gip/2005/15/images/fig60.jpg http://www.oes.ca.gov/Operational/OESHome.nsf/Content/00DB1B291ED19E2988256F64005B419D?OpenDocument

2004 Sumatra Earthquake M 9.3 230,000 people killed in 11 countries due to ground motion and subsequent tsunami Tsunami waves up to 30m (100ft) high

Coastal damage in Thailand from the tsunami Photo from: http://photojournal.jpl.nasa.gov/catalog/PIA06671 Coastal damage in Thailand from the tsunami

Countries most affected by the earthquake and tsunami Map from Wikipedia: http://en.wikipedia.org/wiki/File:2004_Indian_Ocean_earthquake_-_affected_countries.png Countries most affected by the earthquake and tsunami