1. Epicenters 8-3.3 Infer an earthquake’s epicenter from seismographic data.

2. Epicenter EQ: How do scientists locate an earthquake’s epicenter from seismographic data?

3. Seismograph What is a seismograph? What is a seismogram? an instrument used to measure & record seismic waves the vibration record that looks like jagged lines on paper where the seismograph needle moves along with the incoming earthquake waves

4. The Distance from the Seismograph to the Epicenter How do scientists determine the distance between the recording seismograph and the earthquake epicenter? they measure the arrival time between the P waves and S waves

5. Locating the Epicenter How do scientists locate an earthquake’s epicenter? Scientists take seismogram records from three (3) seismograph stations. They use these to determine the distance to the epicenter from each station. (see previous slide) They draw a circle around each station with the correct distance as the radius. The point where the circles intersect is the epicenter. This process is called triangulation.