CASCADE RANGE – Since early last month, small earthquakes have been cropping up deep beneath Mount St Helens at ‘relatively high rates,’ bringing roughly one tremor every few hours.
In the last 30 days, scientists have detected 55 seismic events in the vicinity, and say there may be well over 100 earthquakes linked to the swarm so far.
As reported by the Daily Mail, he activity falls in line with magma recharge thought to be underway since 2008.
But, don’t start panicking just yet – for now, scientists say there’s no sign of ‘imminent eruptive activity.’
Scientists with the Cascades Volcano Observatory (CVO) and the Pacific Northwest Seismic Network (PNSN) first detected the earthquakes on April 21, according to the USGS.
Even though these signs of re-growth are positive, there are also signs of increased seismic activity in the mountain.
“Mount St. Helens is at normal background levels of activity,” Liz Westby, a geologist with the U.S. Geological Survey–Cascades Volcano Observatory, told ABC News. “But a bit out of the ordinary are several small magnitude earthquake swarms in March to May 2016, November 2016 and April 16 to May 5, 2017. During the April 16 to May 5, 2017, swarm, we detected well over 100 earthquakes, all below a magnitude 1.3.”
And even though there is a swarm of earthquakes, Westby said that doesn’t mean that an eruption of Mount St. Helens is coming. Volcanic forecasts can be tricky.
“There are several reasons why it is very unlikely that this swarm is a precursor to imminent eruptive activity at Mount St. Helens. It is similar to ones in the past that did not lead to surface activity. It consists of very small earthquakes occurring at relatively low rates. There are no other geophysical indicators (like surface deformation, tilting, increased volcanic gas emissions) of unrest,” she told ABC News.
Westby said these swarms are extremely interesting and helpful to scientists, since each geophysical signal gives them a better understanding of how a volcano functions.
“This is why we maintain a close watch over these giants, so we can detect the earliest signs of reawakening,” she said.
“There are several reasons why it is very unlikely that this swarm is a precursor to imminent eruptive activity at Mount St. Helens – it is similar to the ones in the past that did not lead to surface activity,” the USGS explains.
“It consists of very small earthquakes occurring at relatively low rates; there are no other geophysical indicators (deformation, tilt, gas) of unrest.”
Thirty-seven years ago, Mount St. Helens erupted, killing 57 people, blasting more than 1,300 feet off the top and raining volcanic ash for miles around.
Today, the volcano has become a world-class outdoor laboratory for the study of volcanoes, ecosystems and forestry, as well as a major recreational and tourist destination.
Some 3.2 billion tons of ash spewed into the surrounding area, according to the United States Geological Survey. Streets and buildings were covered, and the eruption caused an estimated $1 billion in damage.