1. Seismographs Are instruments located at or near the surface of the Earth that record seismic waves.

2. Seismogram Tracing of earthquake motion created by a seismograph

3. When did it happen Seismologist use seismograms to calculate when an earthquake started. A short wiggly line that does not wiggle very much means a small earthquake

4. Size of earthquake Magnitude A long wiggly line means a large earthquake. The size of the earthquake.

5. Where did it happen Epicenter Seismologist use to find an earthquake’s epicenter. Is the point on the Earth’s surface directly above an earthquake’s starting point.

6. A Focus Triangulation Is the point inside the Earth where an earthquake begins. Three seismographs to locate an earthquake. If draw a circle on a map around three different seismographs where the radius of each is the distance from that station to the earthquake, the intersection of those three circles is the epicenter

7. Richer scale Used to measure earthquake strength 2.0-7.0