CHAPTER 8: EARTHQUAKES and EARTH’S INTERIOR

ROOTS:

Crypto = hidden (cryptography)Cumul = mass (cumulative)Cycl = circle (cycle)De = reduce (decelerate)Deca = ten (decade)Deci = one tenth (decibel)Dem = people (democracy)Demi = less than (demigod)Dendr = tree (dendriform – treelike)Dent = tooth (dentist)

Terrashake!http://visservices.sdsc.edu/projects/scec/terashake/2.1/

California Earthquake!

CH 8.1 What is an Earthquake?

Epicenter and Focus http://www.pbs.org/wnet/savageearth/animations/earthquakes/index.html

Earthquake = the vibration of Earth produced by the rapid release of energy.

Focus = point inside Earth where the earthquake starts.

Epicenter = location on the surface directly above the focus.

Fault = fracture in Earth’s crust where movement has occurred.

1906 San Francisco Earthquake Western side of fault moved 4.7 meters to the north.

Over 225,000 people were homeless.Over 3000 people died.

The San Andreas Fault, CA

Based on the movements of the San Andreas fault the Elastic Rebound hypothesis was developed.

A. Existing FaultB. Forces deform

and put pressure on rocks.

C. The pressure overcomes the strength of the rocks. The rocks break and slip.

D. The pressure is relieved and the ground stops moving.

http://www.sceyencestudios.com/animation.htm

Elastic Rebound Hypothesis

Pg.. 220 Figure 4

UNCONFORMITY ????? http://www.classzone.com/books/earth_science/terc/content/visualizations/es2902/es2902page01.cfm?chapter_no=visualization

Most earthquakes are produced by the rapid release of elastic energy stored in rock that has been subjected to great forces. When the pressure on the rock exceeds the strength of the rock, the rock suddenly breaks.

Aftershocks and Foreshocks

Foreshocks = small earthquakes that occur prior to a larger earthquake.

Aftershocks = small earthquakes that occur following a larger earthquake.

Foreshocks and Aftershockshttp://earthquake.usgs.gov/learning/animations/animation.php?flash_title=Foreshocks+Flash+Animation&flash_file=aftershock&flash_width=400&flash_height=275