The United States Geological Survey (USGS) has reported a disquieting level of seismic activity below the infamous Mount St. Helens in Washington State. The volcano erupted in an extremely violent explosion in 1980, killing 57 people and thousands of livestock. Now, the USGS has detected over 120 earthquakes which have occurred in four separate “swarms,” creating worry that another eruption might soon be on the way.
While the earthquakes were all relatively weak - between .2 and .5 on the Richter scale - they have geologists speculating that the volcano could be recharging for another potentially deadly explosion. According to a USGS press release, the volcano is likely “recharging:"
The magmatic system is likely imparting its own stresses on the crust around and above it, as the system slowly recharges. The stresses drive fluids through cracks, producing the small quakes. Subtle evidence of recharge has been observed since 2008 and can continue for many years. It is a sign that Mount St. Helens remains an active volcano.
Weston Thelen, a USGS seismologist with the Cascades Volcano Observatory, told the Seattle Times that while these earthquakes are a sobering hint that the volcano is still active, there is no way of knowing exactly when the next big one will be:
Each of these little earthquakes is a clue and a reminder we are marching toward an eruption someday [...] there’s nothing in this little modest seismicity, and none since 2008, that is a really good indicator of when that eruption will be.
Earlier this year, a similar swarm of 180 earthquakes was detected under the volcano. The frequency of these earthquake swarms is particularly worrying given other current developments in Mount St. Helens research. Just last month, a team of seismologists conducted surveys of the underground network of lava tunnels beneath Mount St. Helens, revealing that there remains much we don’t know about the inner workings of this once-deadly volcano.