A “swarm” of 130 earthquakes have trembled beneath Mount St Helens in the past eight weeks, seismologists have revealed. The US Geological Survey (USGS) said the series of small quakes showed “the volcano is still very much alive”. Although there are no signs of an imminent eruption, the volcano - 95 miles south of Seattle - is recharging, the seismologists have said. An eruption in 1980 blasted more than 1,300ft off the top of the mountain and left 50 people dead.
Earthquake rates have been steadily increasing since March, reaching nearly 40 located earthquakes per week.
US Geological Survey
Most of the tremors are less than 0.5 in magnitude and the largest was 1.3 - rumbling about 1.2 to four miles beneath the surface. Although the quakes are relatively small, it is the frequency that is concerning scientists. The USGS said the volcano’s collection of magma is “re-pressurising”, but said the process can continue for years without an eruption. Similar patterns of “earthquake swarms” were detected in 2013, 2014 and in the 1990s, said the USGS.