1. Monitoring Earthquakes 6.3p.178-183

2. Detecting Earthquakes As early as 2000 years ago the Chinese had developed an instrument to detect earthquakes. As early as 2000 years ago the Chinese had developed an instrument to detect earthquakes. The modern day instrument is a seismograph. A seismograph is a heavy weight attached to a frame by a spring or wire. A pen is connected to the weight and rests on a drum covered by paper. As the drum rotates the pen writes on the paper. The modern day instrument is a seismograph. A seismograph is a heavy weight attached to a frame by a spring or wire. A pen is connected to the weight and rests on a drum covered by paper. As the drum rotates the pen writes on the paper.

3. Seismograms When an earthquake occurs the paper makes a picture of graph of the earthquake. These zigzag patterns are called, When an earthquake occurs the paper makes a picture of graph of the earthquake. These zigzag patterns are called, P,S and Surface waves all show up differently on seismogram. See p. 179 P,S and Surface waves all show up differently on seismogram. See p. 179

4. Other Earthquake instruments Scientist sometimes place other instruments in earthquake prone areas. Scientist sometimes place other instruments in earthquake prone areas. Tiltmeters: measure the tilt or raising of the ground (measure vertical movement) works like a level. Tiltmeters: measure the tilt or raising of the ground (measure vertical movement) works like a level. Creep meters: uses a wire that is stretched across a fault attached to a post and measures horizontal movement when other end shifts. Creep meters: uses a wire that is stretched across a fault attached to a post and measures horizontal movement when other end shifts. Laser-ranging devices: laser beams detect horizontal movement. Laser strikes a reflector and then bounces back. If reflector moves they are notified. Laser-ranging devices: laser beams detect horizontal movement. Laser strikes a reflector and then bounces back. If reflector moves they are notified.

5. GPS Satellites: markers are set up and using GPS the elevation and any movement can be detected with satellites. GPS Satellites: markers are set up and using GPS the elevation and any movement can be detected with satellites. Why do they want all this data? To try to predict when earthquakes will occur and where. Why do they want all this data? To try to predict when earthquakes will occur and where.

6. Mapping/monitoring Faults Mapping all the faults is crucial to know where an earthquake will occur. Mapping all the faults is crucial to know where an earthquake will occur. They then monitor friction. The amount of friction built up in an area will determine how big the earthquakes will be. They then monitor friction. The amount of friction built up in an area will determine how big the earthquakes will be. Hardly any: no stress and rarely any big earthquakes Hardly any: no stress and rarely any big earthquakes Moderate friction: small earthquakes Moderate friction: small earthquakes High friction: big earthquakes High friction: big earthquakes