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.”