The small magnitude earthquakes are thought to be associated with the “arrival of additional magma,” according to USGS – a process called “recharge.”
SKAMANIA COUNTY, Wash. — Hundreds of small-magnitude earthquakes registered below Mount St. Helens could indicate that the volcano is going through “recharge” – a process where additional magma accumulates below the volcano.
Between Feb. 1 and early June, the United States Geological Survey (USGS) registered 350 earthquakes occurring at a median depth of 3.5 miles below sea level. The vast majority of the earthquakes have been below a magnitude 1.0, which is too small to be registered on the surface. The largest earthquake
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