UTAH COUNTY, Utah ( ABC4) — A sizeable earthquake hit near Utah County on Thursday afternoon. According to the U.S.

Earthquakes and seismic activity often happen with sudden movements underground with tectonic plates. Seismographs are used by scientists to measure the time, location and strength of an earthquake.

At least 21 quakes have rattled the East Bay city.

Often in these weekly Night Sky columns I refer to the magnitude of a star or planet. The concept of magnitude is relatively easy to grasp. Put simply, magnitude indicates an object’s degree of ...

What does “moment magnitude” mean, and how do scientists determine the strength of a rupture in the earth? By Henry Fountain Henry Fountain spent a quarter century covering science for The Times. He ...