USArray is a 15-year program to place a dense network of permanent and portable seismographs across the continental United States. The seismographs record local, regional, and distant (teleseismic) earthquakes.

USArray consists of four interrelated parts

Question 1:
How do seismic waves make an image of the interior of the Earth?
Question 2:
How does a dense array of seismometers improve scientific results?

How does a Transportable Array seismic station work?