A swarm of small earthquakes is now disturbing the region under Mount St. Helens in Skamania County, Washington since March, where U.S. Geological Survey scientists believe that this volcano is now recharging with magma.
According to Pacific Northwest Seismic Network scientists, they have detected more than 130 earthquakes located in between 1.2 to four miles underneath the volcano beginning March 13. Researchers also revealed that their data registered a magnitude of 0.5 or less, where some of the quakes are too weak to be detected.
Scientists confirm that there is no clear indication that a massive eruption will occur anytime soon.
Researchers add that there are no anomalous gases, increasing inflation of the ground or even shallow seismicity that have been determined from this swarm, leading to no signs of an imminent volcano eruption. They also say that a recharge can continue for many years underneath a volcano without any eruption event, based on observations of Mount St. Helens between 1987 to 2004.
The USGS also determined that these quakes are volcano tectonic that are more often than not observed in active magma systems. These smaller quakes or tremors are usually caused by stress as fluids are pushed through cracks.
Researchers explain this geological phenomenon when the magma chamber is releasing and distributing its stresses and forces its way above the crust and the surface above it, indicating a system that is slowly recharging. This stress is the driving mechanism behind fluid movement through cracks, generating smaller quakes. This current pattern of seismicity is also similar to past swarms of Mount St. Helens in 2013 and 2014. Back in the 1990s, recharge swarms released higher earthquake rates and energy emissions.
USGS scientists also revealed that the data they have collected is a strong indication that the volcano is still alive, where the amount of quakes have been increasing since March, that reach almost 40 every week.
The last biggest eruption of Mount St. Helens was last May 1980, some 36 years ago, where this massive eruption killed 57 people in Washington, as this eruption released 1,300 feet of volcanic ash into the atmosphere.