The Long Valley Caldera is experiencing a large seismic swarm. As magma moves through the earth, it displaces and fractures rock along the way. This movement causes earthquakes that can be recorded with seismometers at the surface of the earth. Seismic monitoring is the most used technique for volcano surveillance. Volcanic earthquakes often provide the initial sign of volcanic unrest. The last eruption at the volcano is said to have occurred 700,000 years ago and is long over-due. […]