Scientists: Earthquake Swarms Detected Beneath Mount St. Helens

More than 130 low-magnitude earthquakes have been reported underneath Mount St. Helens since March 14. The USGS believes that the volcano is likely recharging its magma chamber and causing stress on the earth's crust, therefore producing the small earthquakes. Similar patterns have been observed near the volcano in the past and an eruption is not believed to be imminent. Photo by USGS Volcanoes/Facebook

SEATTLE, May 7 (UPI) — Scientist said a number of low-magnitude earthquakes taking place beneath Mount St. Helens could be the result of the volcano slowly recharging.

More than 130 earthquakes have been detected in the area around the volcano since March 14, the U.S. Geological Survey said. The largest quake measured a magnitude of 1.3 with most having magnitudes of 0.5 or less.

The USGS said Mount St. Helen is likely recharging its magma chamber, causing stress on the earth’s crust and producing small earthquakes.

“There is absolutely no sign that it will erupt anytime soon, but the data we collect tells us that the volcano is still very much alive,” the USGS said.

Mount St. Helens has been one of the most heavily monitored volcanoes in the world since its catastrophic eruption in 1980. The USGS has tracked similar patterns with the volcano throughout the years since then.

“The current pattern of seismicity is similar to swarms seen at Mount St. Helens in 2013 and 2014; recharge swarms in the 1990s had much higher earthquake rates and energy release,” scientists said. “As was observed at Mount St. Helens between 1987-2004, recharge can continue for many years beneath a volcano without an eruption.”

The USGS said there are no signs of an imminent eruption at Mount St. Helens. There have been no anomalous gases, increases in ground inflation or shallow seismicity with this swarm.

“Each volcano behaves a little differently,” the USGS stated. “Research has led to a greater understanding of seismic signals and improved our ability to characterize what is going on at depth, and, if needed, provide eruption warnings.”

Mt st HelensMt st Helens 2

'Mount St. Helens earthquake record during times of magma recharge. The top plot is the number of located earthquakes per week in the @[332008586832112:274:Pacific Northwest Seismic Network] catalog. The bottom plot shows the earthquake depths with time. Earthquakes are plotted as circles with the size of the circle corresponding to the magnitude of the earthquake (see legend). Both plots show the time period from 1987 to September 2004, and 2008 to May 4 2016. The 2004 to 2008 eruption at Mount St. Helens has been removed from this record for simplicity. USGS graphic prepared May 5, 2016 by Wes Thelen.'
'During the first part of the swarm that began in March, 2016, Mount St. Helens' September Lobe monitoring station (located on the 1980-86 dome) was buried in deep snow and not transmitting data. USGS-Cascades Volcano Observatory Technicians Kelly Swinford and Amberlee Darold (pictured in the snow pit) dug out the station on March 30, restoring data flow and improving our ability to monitor the swarm. The view is to the northeast with Spirit Lake in the background. USGS image taken March 30, 2016 by Seth Moran.'


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