RLNI+2.4

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Vocabulary

 * Creep meters**: measures the movement along a strike slip fault
 * Laser ranging devices**: device that measures changes with a laser beam and a reflector
 * Tiltmeters**: measures tilting of the ground, works like a carpenter's level
 * Satellite moniter**: uses radar to take picture of faults

**Device that Monitor Faults**

 * there are four different types of instruments
 * creep meters
 * a creep meter uses a wire stretched across a fault to measure horizontal movement of the ground
 * on one side of the ground, the wire is tied to the pole
 * on the other side of the ground, the wire is attached to a weight that can slide if the fault moves
 * geologists can measure how much the fault has moved because of the weight
 * laser-ranging devices
 * this device uses a laser beam to find tiny fault movements
 * this device can find any change in the distance to the reflector
 * tiltmeters
 * this instrument measures tilting of the ground
 * seismologists use this to consist of two bulbs that are filled with liquid and connected to a hollow stem
 * if the land rises, the liquid will go from one bulb to the other bulb
 * each bulb has a scale to measure the depth of the liquid
 * geologists read the scales to measure how much the fault has moved
 * satellite monitors
 * the satellite bounces radio waves off the ground
 * as the waves echo back into space, the satellite records them
 * the distance from the ground to the satellite changes, depends when the ground moves
 * these changes in elevation result when stress deforms the ground along the fault

**Monitoring Risks in the United States**

 * geologists can't predict earthquakes
 * the major earthquakes is the area of the pacific