Question

3 multiple choice 1 point
how many seismographs are needed to triangulate the origin of an earthquake?
2
1
4
3

Explanation:

Triangulation for an earthquake's origin relies on using the difference in arrival times of seismic waves at multiple stations. Two stations only narrow the location to a line, while three stations create three intersecting circles (from distance calculations) that pinpoint a single unique location, the earthquake's epicenter.

Answer:

3