NSSS2.4

toc =2.4 Monitoring Faults=

Devices that monitor faults

 * Geologists have invented instruments that can record ground movements
 * Creep meters
 * Wires are stretched across a fault to measure the movement of the fault horizontally
 * One side is held by a post while the other is held by a weight that moves when the fault moves.[[image:torreavenue-3.jpg]]
 * Laser-ranging devices
 * A laser is used to detect even the tiniest of fault movements
 * If the laser is delayed even by a fraction of a second, a device detects the change and marks it.[[image:torreavenue-2.jpg]]
 * Tilt-meters
 * Measures the tilting ground
 * There are two bulbs, each filled with water, that move from one side to another when the fault rises or falls
 * Each bulb contains a measuring device to measure the liquid
 * Satellite Monitors
 * Satellites are equipped with radar to take picture of faults
 * The satellite sends radio waves to the Earth and, when the waves come back in, marks the time
 * If times vary, geologists can take a look at the photos to see slight changes in elevation

Monitoring Risk in the U.S.A

 * Scientists cannot accurately predict earthquakes
 * Geologists use the knowledge that earthquakes occur wherever plate movement stores energy along faults
 * Geologists determine they can find where an earthquake can occur based where past earthquakes have happened
 * Most likely to be hit with an earthquake that is Major.
 * San Francisco
 * Los Angeles
 * Salt Lake City
 * Charleston
 * Boston
 * Seattle
 * Most likely to be hit with an earthquake that is moderate.
 * Phoenix
 * St. Louis
 * Atlanta
 * Cleveland
 * Most likely to be hit with an earthquake that is minor.
 * Denver
 * Minneapolis
 * Chicago
 * New Orleans
 * Cleveland
 * Washington D.C
 * Philadelphia
 * New York
 * Area where earthquakes never strike.
 * Houston
 * Miami