Volcano tectonic earthquake

A volcano tectonic earthquake is an earthquake induced by the movement (injection or withdrawal) of magma. The movement results in pressure changes in the rock around where the magma has experienced stress. At some point, the rock may break or move. The earthquakes may also be related to dike intrusion and may occur as earthquake swarms. An example is the 2007–2008 Nazko earthquake swarm in central British Columbia, Canada.
Other types of seismic activity related to volcanoes and their eruptions are long period seismic waves, which are from sudden sporadic movement of magma, which is blocked from moving due to a blockage. Another is a harmonic tremor, which is steady movement of magma, deep in the mantle.
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