seismographs

Wyo. Mine Blast Picked Up On Seismographs
GILLETTE, Wyo. (AP) — An explosion at a coal mine northeast Wyoming was big enough to register on seismographs on the scale of a small earthquake. Some people in Gillette reported feeling the ground shake from 16 miles away. The U.S. Geological Survey recorded the blast at 11:11 a.m. Tuesday.…