Four swarms of more than 120 earthquakes shook Mt. St. Helens in late November in less than a week, The Seattle Times reports.
The quakes – so tiny that you wouldn’t have felt them if on the epicenter – hit one to two miles beneath the volcano’s surface.
Scientists say the quakes reveal the volcano is likely recharging.
A seismologist with the Cascades Volcano Observatory in Vancouver told The Seattle Times that each of these little quakes is a reminder of an eruption someday, but the recent swarms do not indicate when the next eruption may be.
They think that the volcano releases gas and fluids that travel into the cracks as magma is stored.
KIRO 7 News reported a similar situation that happened in March when 180 small earthquakes occurred beneath the volcano over a period of eight weeks.
As was seen at Mount St. Helens between 1987 and 2004, recharge can continue for many years beneath a volcano without an eruption.
Since the catastrophic eruption of May 18, 1980, scientists have been conducting research and collecting data on the volcano to learn more about its typical behavior.
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