Its scarred and jagged crater is a reminder of the terrible devastation that Mount St Helens wrought over the Washington countryside 35 years ago.
Now a new study of the volcanic plumbing lurking beneath the 8,363ft (2,459 metre) summit suggests the volcano could yet again blow its top in an explosive eruption.
Geologists studying the volcano, which is responsible for the most deadly eruption in US history, have discovered a second enormous magma chamber buried far beneath the surface.
Geologists have discovered the magma chamber beneath Mount St Helens (pictured) is fed by a much larger chamber deeper below the Earth’s crust. They said earthquakes around the volcano are a sign of magma pumping from the lower reservoir into the upper one, and this could reveal clues about an impending eruption
This giant pool of molten rock, which lies between seven to 25 miles (40km) below the surface, is connected to a slightly smaller chamber that lies directly beneath the mountain.
The researchers also believe a second neighbouring volcano – Mount Adams – may also be fed from the deeper magma chamber.
PREDICTING A SUPER-ERUPTION
It is a discovery that could save the life of million, and safeguard entire species.
Researchers claim to have worked out how to accurately predict the eruption of ‘supervolcanoes’ that blanket the earth in giant ash clouds triggering a ‘nuclear winter’.
They say the discovery could reveal exactly when giant pools of magma greater than 100 cubic miles in volume and formed a few miles below the surface will erupt.
Despite considerable study, geologists are still debating how quickly these magma pools can be activated and erupted, with estimates ranging from millions to hundreds of years.
Now a team of geologists have developed a new ‘geospeedometer’ that they argue can help resolve this controversy by providing direct measurements of how long the most explosive types of magma existed as melt-rich bodies of crystal-poor magma before they erupted.
They have applied their new technique to two super-eruption sites and a pair of very large eruptions and found that it took them no more than 500 years to move from formation to eruption.
They said a series of distinct earthquakes in the months leading up to the massive eruption on 18 May 1980, which killed 57 people, may have been caused by the pumping of magma from the lower to the upper chamber.
This caused the pressure inside the upper chamber to increase dramatically until it erupted explosively.
In a presentation to the annual meeting of the Geological Society of America in Baltimore, Maryland, the researchers said there have been more recent tremors in the area that suggest more magma is being injected.
Mount St Helens began erupting again back in 2004 producing a new lava dome, but fell silent in July 2008.
However, it is still considered to be a high-risk volcano and the US Geological Survey are closely monitoring it for signs for renewed unrest.
Seismologists added the new findings could provide a vital early warning system for potential eruptions at the site.
Eric Kiser, from Rice University, in Houston, Texas, who was among those working on the project, told the journal Science: ‘We can only now understand that those earthquakes are connecting those magma reservoirs.
‘They could be an indication that you have migration of fluid between the two bodies.’
The findings are among the first to emerge from a project to image the magma under Mount St Helens, called IMUSH.
The IMUSH project has detected signs that a second larger magma chamber may lie beneath Mount St Helens, filling the chamber directly under the volcano from below (illustrated) through a series of earthquakes. The chamber may also connect Mount St Helens to other nearby volcanoes
Lava, steam and ash began erupting from Mount St Helens in 2004 but it fell silent again in 2008. Geologists have been closely monitoring the volcano for signs that the unrest may begin again
Using explosive shots fired into the ground, they have been able to build up a picture of the crust around the volcano with a network of 2,500 seismometers.
Combined with data from the frequent small earthquakes that shake the area around Mount St Helens, the experts have been able to reconstruct the structure up to 24 miles (37km) beneath the volcano.
They are hoping more long-term data from future earthquake, and the background ‘hum’ produced by the Earth’s crust itself, will allow them to recreate a picture of what lies up to 50 miles (80km) beneath the surface.
Speaking at the annual meeting of the Geological Society of America, Dr Alan Levander, a geologist at Rice University, said the upper magma chamber directly beneath Mount St. Helens lies between 2 and 8 miles (3km and 13km) beneath the surface.
They said a series of distinct earthquakes in the months leading up to the massive eruption on 18 May 1980 (picutred), which killed 57 people, may have been caused by the pumping of magma from the lower to the upper chamber. Using seismometers, the experts reconstructed up to 24 miles (40km) beneath the volcano