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Vocabulary

 * Creep Meters**: A creep meter uses a wire stretched across the fault to measure movement of the ground.
 * Laser-Ranging Devices**: It uses a laser beam to detect fault movements.
 * Tiltmeters**: A tiltmeter measures the tilting of the ground.
 * Satellite Monitors**: The satellite bounces off radio waves off the ground.

Devices that Monitor Faults

 * There are four instruments that geologists put in place that measure stress and deformation in the crust.
 * Creep Meters
 * A creep meter uses a wire stretched across a fault to measure movement of the ground.
 * On the other side, the the wire is anchored to a post.
 * On the other side of the wire, it is attached to a weight that can slide if the fault moves.
 * Geologists can measure the amount the moved by measuring how much the weight have moved.
 * Laser-ranging devices
 * It uses a laser beam to detect tiny fault movements.
 * It calculates any change in the time needed for the laser beam to taavel to the reflector and back.
 * The device can detect change in the distance to the reflector.
 * Tiltmeters
 * It measures tilting of the ground.
 * A tiltmeter is like a carpenter's level.
 * There is two bulbs that are filled with a liquid and connected with a hollow stem.
 * Geologists fill the tiltmeter with water and if the land rises or falls, the water in the two bulbs will tilt.
 * Liquid will slightly flow from one bulb from another.
 * Each bulb contains a measuring scale to measure the depth of the bulbs.
 * Geologists read the scales to measure the amount occurring along any fault.
 * Satellite Monitors
 * Geologists use satellites equipped with radar to make images of faults.
 * The satellites bounces off radio waves off the ground.
 * The time it takes for the waves to make their round trip provides measurements of the distance to the ground.
 * Geologists compares changes of the ground taken at the same places, at the different time.

Monitoring Risk in the United States

 * Even with a lot of data, geologists can not predict accurately when and where an earthquake will strike.
 * Exactly what will happen during an earthquake is always uncertain.
 * Geologists do know where earthquakes are likely to happen.



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