Mount St Helens earthquake activity does not necessarily mean eruption

Discovery : Despite some 130 small earthquakes that have occurred since 14 March, Mount St Helens in Washington State is not likely to erupt anytime soon, according to the US Geological Survey (USGS). The earthquake activity is reminiscent of what occurred more than 35 years ago, when a series of small quakes starting in March 1980 preceded the cataclysmic 18 May eruption that killed 57 people. Earthquakes around a volcano are caused by magma bubbling up from deep within Earth and putting pressure on the surrounding rock layers, which can fracture and slip. The magma pools in underground chambers, where it can collect until there is enough pressure to erupt to the surface. Such recharging of a volcanic magma chamber, although worrisome, occurs over long periods of time. Similar seismic swarms occurred around Mount St Helens in 2013 and 2014. Nonetheless, the USGS continues to use its state-of-the-art volcano monitoring network to watch for any other signs, such as changes in gas emissions, shallow quakes, or crust deformation, that indicate a volcanic eruption is imminent.