1. CH 5 Prentice Hall p.168-171 CH 5 Prentice Hall p.168-171 Faults Monitoring

2. Instruments used to observe changes. – Measure stress and deformation of the crust. Creep Meters Laser-Ranging Devices Tiltmeters Satellites Devices that Monitor Faults

3. Creep Meters A meter with a wire stretched across a fault to measure horizontal movement. – Wire is anchored to a post. – The wire on the other side of the fault has a weight attached to it. – Movement can be determined by measuring how much the weight has moved.

4. Laser-Ranging Devices Detects tiny fault movements with a laser. – The device measures the time it takes for the beam to travel to the reflector and back. – Can detect any change in distance.

5. Tiltmeters Measures the tilting of the ground. – Acts like a carpenters level. Geologists read the scales to see the amount of tilting along a fault.

6. Satellites Satellites bounce radio waves off the ground and the satellite records them. Can detect small changes in elevation, may result when stress deforms the ground.

7. Geologists cannot predict earthquakes. – Exactly what will happen remains uncertain. Stress may build up and not release an earthquake. Or stress may be released in another part of the fault. Geologists know that earthquakes are likely wherever plate movements store energy in the rock along faults. – Geologists can determine the risk by where faults are active and other earthquakes have occurred. Monitoring Risk in the US