2.4 Monitoring Faults


Devices that Monitor Faults

  • the geologists use machines to remember how the ground moves during an earthquake
    • to look closely at the differences in the ground, geologists put machines in the ground that tell if there is tension (stress) and if the ground starts to deform
    • sadly, earthquakes usually start without any notice
      • the only hint about an incoming earthquake is the little ascend or descend in the elevation or the slant of ground
        • the machines that geologists use to observe these motions are creep meters,laser ranging devices, tiltmeters, and satellites

Creep Meters

  • a creep meter uses a wire extended across a fault to measure the horizontal proposition of the earth on one side of a fault, the wire is tied to a pole on the other side of the fault, the wire is stuck onto a heavy item that can slide if the fault makes any movement.
    • geologists can see how much the fault has moved by taking a measurement of how much the heavy object has moved against the fault


Laser-Ranging Devices

  • a laser-ranging device uses a laser beam to find any small changes in the fault
    • this instrument measures the difference in the time that takes the laser beam to get to the reflector and return
      • this gadget can find any difference in the length to the reflector


  • it measures if there is any tilting on the ground
    • it uses to bulbs that are filled with liquid and is connected by a hollow stem
    • it can tell if the land rises or falls

Satellite Monitors

  • a satellite that bounces radio waves off the ground to detect if there's any change on the earth's surface
  • it can also take pictures of the ground surface to look if there are any changes on the earth's surface

Monitoring Risk in the United States

  • geologists can't predict when and where and earthquake will happen
  • geologists are able to tell where earthquakes will likely happen
    • by studying where active faults are
    • by studying where past earthquakes have occurred
      • the highest rick of earthquakes are
        • along the Pacific coast of the states in California, Washington, and Alaska
          • the reason why the risk is so high here is because this is where the Pacific and North America plates meet
            • some very dangerous earthquakes occur on the east of the Rocky Mountains

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