USGS monitoring recent seismic activity beneath Mount St. Helens - KPTV - FOX 12

USGS monitoring recent seismic activity beneath Mount St. Helens

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Courtesy: USGS Courtesy: USGS
SKAMANIA COUNTY, WA (KPTV) -

The United States Geological Survey has been monitoring recent seismic activity underneath Mount St. Helens.

According to the USGS Volcanos Facebook page, a number of small earthquakes have hit beneath the active volcano between the dates of March 16 and May 5.

The quakes have been between 2 and 7 kilometers deep and have low magnitudes of .5 or less, too small to be felt on the surface.

The USGS said earthquake rates in the Pacific Northwest have been steadily rising since March, averaging about 40 quakes each week.

According to officials, the swarms of earthquakes are volcano-tectonic in nature and are signs of activity in hydrothermal and magmatic systems. 

"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." the USGS said in their Facebook post. 

However the current pattern of seismicity is similar to earthquake swarms seen at Mount St. Helens in 2013 and 2014. Swarms in the 1990s had much higher earthquake rates.

Experts said there are no signs of an imminent eruption of the volcano.

“No anomalous gas, increases in ground inflation or shallow seismicity have been detected with this swarm,” said USGS Volcanoes officials.  

The USGS added that seismic activity or recharge can occur for many years beneath a volcano without an eruption.

To follow activity updates in the Cascades Volcano Observatory area, go to Volcanos.USGS.gov. 

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