Scientists have been left baffled by a record spike in earthquakes near Washington’s Mount Adams that has been dormant for thousands of years.
The volcano is deemed a ‘high threat’ due to its ability to trigger landslides, debris avalanches and mudflow that can travel up to 50 miles per hour down the slope, which would put thousand of people at risk.
The region typically sees quakes once very three years, but the US Geological Survey (USGS) detected the six in September, which ranged from a 0.9 to 2.0 magnitude.
While very weak, previous studies have suggested that swarms of small earthquakes can precede a volcanic eruption.
Scientists have recorded a major increase in earthquakes around the most active volcano in Washington state – the Mount Adams volcano
Quakes near Mount Adams typically occur only once every two to three years, and this the highest number of earthquakes to occur in a single month since scientists began recording quakes in this area in 1982.
All six of the earthquakes were recorded at a seismic station seven miles southwest of the Mount Adams summit, located in the southwest in the Gifford Pinchot National Forest, and at other stations much farther away from the volcano.
Scientists with the Cascades Volcano Observatory (CVO) and Pacific Northwest Seismic Network (PNSN) plan to install a set of temporary seismic stations around Mount Adams to investigate the size, location and depth of the quakes, according to the USGS.
‘This will improve our ability to locate smaller earthquakes with more certainty and assist in understanding the cause of these earthquakes. The results of our findings will determine if any additional actions are needed,’ USGS officials wrote in a statement.
In some cases, earthquakes near volcanoes can trigger eruptions.
But this only occurs if the quake is large (greater than magnitude 6) and the volcano is already poised to erupt.
When those conditions are met, the quake could cause dissolved gases to come out of the magma similarly to a shaken soda bottle, which increases the pressure inside the volcano and may lead to an eruption.
But these six quakes were far too small to trigger an eruption.
And the USGS said there is no imminent eruption threat.
Therefore, this uptick in seismic activity is not a sign that Mount Adams is about to blow, USGS officials stated.
Mount Adams formed roughly 520,000 years ago. It’s located roughly 70 miles northeast of Vancouver, Washington and Portland, Oregon.
The biggest threat to people living near this volcano is lahars, or muddy flows of rock, ash and ice, like the one that destroyed this town in Columbia after a volcanic eruption in 1985
Even through Mount Adams is considered a ‘high threat’ volcano, it hasn’t erupted for thousands of years.
Scientists estimated that its mot recent eruption occurred sometime between 3,800 and 7,600 years ago.
And throughout its history, Mount Adams has mainly produced effusive eruptions, which are different from explosive eruptions in that they do not send lava, gas and ash shooting into the sky, but rather form slow-moving lava flows that creep down the volcano’s sides.
But the biggest threat to people living near this volcano isn’t an eruption.
It’s actually avalanches, landslides and lahars, or muddy flows of rock, ash and ice that ‘surge downstream like rapidly flowing concrete’ and can occur during eruptive or non-eruptive periods, according to the USGS.
‘The ice-capped summit conceals large volumes of hydrothermally weakened rock, and future landslides of this weakened rock could generate far-traveled lahars,’ USGS officials wrote.
The new, temporary monitoring stations will allow scientists to collect more data on the seismic activity below Mount Adams, helping them detect smaller earthquakes and better understand what caused the recent uptick in activity.
‘The results of our findings will determine if any additional actions are needed,’ USGS officials stated.