Mount St. Helens

Mount St. Helens Recharges Its Magma Stores Causing A Series Of Earthquake Swarms

Mount St. Helens is recharging its magma stores, which has caused a series of earthquake swarms in the area. The Pacific Northwest Seismic Network has recorded 130 earthquakes underneath the volcano over the past eight weeks. The recorded earthquakes do not include the dozens of other quakes that were likely too small for the network to detect. The earthquakes have been steadily increasing with the network noting that there are now roughly 40 earthquakes per week being recorded beneath Mount St. Helens. The U.S. Geological Survey reports that the earthquake swarms are likely an indicator that the magma chamber beneath the volcano is being recharged.

The USGS released a statement regarding the swarm of earthquakes that continues at Mount St. Helens. The report indicates that 130 earthquakes have been recorded at the location in the past eight weeks with the incident rate of recorded earthquakes continuing to climb in recent weeks with an average of 40 quakes per week reported. The earthquakes were described by the USGS as “volcano-tectonic” in nature which is indicative of a slip on a small fault. This, according to the USGS report, means that the magma chamber underneath Mount St. Helens is likely recharging.

“The magma chamber is likely imparting its own stresses on the crust around and above it, as the system slowly recharges. The stress drives fluids through cracks, producing the small quakes.”

Mt. St. Helens
Mount St. Helens lets off steam in 2004. (Photo by Jon Major/USGS via Getty Images)

Though scientists are claiming that the volcano is recharging, it is noted that there is currently no imminent danger to those who live near the infamous Mount St. Helens. Discovery reports that the earthquake swarm does not mean that the volcano is about to erupt. Instead, it was noted that these type of recharging events are common for active volcanoes and that other pre-eruption signs would need to be present for the USGS to determine an eruption was imminent.

Erik Klemetti, an assistant professor of Geosciences at Denison University, points out that this isn’t the first series of earthquake swarms underneath Mount St. Helens in the years following the 1980 eruption that lead to 57 deaths. Klemetti says that a “big recharge event” took place in 1998 and 1999 that did not produce minor eruptions until five years later. The eruptions from 2004 to 2008 were deemed “non-catastrophic” as the volcano did not erupt explosively like in 1980, but rather experienced a slow extrusion of magma rebuilding a lava dome.

The latest Mount St. Helens earthquake swarm could indicate another future “non-catastrophic” eruption that could continue to build the lava dome, or it could signal an impending explosive release. However, scientists say there are currently no signs of either type of eruption and that they will continue to closely monitor the situation.

The earthquakes alone are not enough to signal a threat to the region, instead scientists say they will look for new gas emissions, deformation of the crust near the volcano and shallow earthquakes before issuing a warning. If any of these signs are present along with the earthquakes, an imminent eruption will likely be declared.

“No anomalous gases, increases in ground inflation or shallow seismicity have been detected with this swarm, and there are no signs of an imminent eruption.”

Fortunately for those that live near Mount St. Helens, the volcano is one of the most monitored volcanoes on the planet with an extensive system of complex monitoring devices in place.

[Image via Shutterstock]

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