GEOLOGY

Detailed explanation-1: -To locate the epicenter of an earthquake, geologists need data from two or more seismographs. In a seismograph, seismic waves cause the drum to vibrate. On a seismogram, higher lines drawn in the paper indicate weaker seismic waves. The first waves shown on a seismogram are the P waves.

Detailed explanation-2: -Three or more seismograph stations are needed to locate the epicenter of an earthquake through triangulation . Using the arrival-time difference from the first P wave to the first S wave, one can determine the distance from the epicenter, but not the direction.

Detailed explanation-3: -You need one because the epicenter will be somewhere along that circle. You need three because three is the minimum number of circles that will intersect at one point.

Detailed explanation-4: -Seismic stations detect earthquakes by the tracings made on seismographs. Tracings made at three separate seismic stations are needed to locate an earthquake epicenter.

Detailed explanation-5: -Each seismograph records the times when the first (P waves) and second (S waves) seismic waves arrive. From that information, scientists can determine how fast the waves are traveling. Knowing this helps them calculate the distance from the epicenter to each seismograph.