Which steps do geologists use to find the epicenter of an earthquake? check all that apply.
they look at data from at least three seismographs.
they locate the point where circles intersect one another.
they measure the difference between arrival of p waves and s waves.
they draw circles around the epicenter from three locations.
they obtain information about the intensity of earthquakes from seismographs.

They draw circles around the epicenter from three locations.

Explanation:

Geologists use triangulation method to determine the epicenter of an earthquake.

The epicenter of an earthquake is a point on the earth surface directly above the focus. The focus is the point beneath the surface where the earthquake occurs.

To determine the epicenter of an earthquake, we simply draw three circles whose point of intersection will be the epicenter. How do we now draw the circle?

From a seismogram obtained from 3 stations, we can deduce the time it takes a wave to travel. We simply compare the time lag between the first occurrence of the s-waves and that of the p-waves. Now that we have the time, we can determine the distance travelled by the wave. Since we know that the velocity of waves are constant, we simply use the relationship between velocity and time to find the unknown distance.

Using the distance as the radius, we draw three circles from different seismograph stations on a map. The point where the three circles intersects marks the epicenter of the earthquake.

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