Question

how can we find an earthquake’s epicenter?
__ seismograph stations are needed to locate the __ of an earthquake
a ____ where the radius equals the distance to the epicenter is drawn
the ____ of the three circles locates the epicenter!

Explanation:

To find an earthquake's epicenter, we use the method of triangulation with seismograph stations.

1. First blank: Three seismograph stations are needed because with one station, we can only know the distance (a circle), with two we have two circles (two possible points), and three give a unique intersection.
2. Second blank: We want to locate the "epicenter" of the earthquake.
3. Third blank: For each station, we draw a "circle" where the radius is the distance from the station to the epicenter (calculated from the time difference of seismic waves).
4. Fourth blank: The "intersection" (or "point of intersection") of the three circles is the epicenter, as that's the only point common to all three circles (representing the distance from each station).

Answer:

• \_\_Three\_\_ seismograph stations are needed to locate the \_\_epicenter\_\_ of an earthquake
• A \_\_circle\_\_ where the radius equals the distance to the epicenter is drawn
• The \_\_intersection (or point of intersection)\_\_ of the three circles locates the epicenter!