New magma chambers have spurred fears that Mount St. Helens might erupt again, but researchers are now trying to dissipate those rumors.
Previously, it had been thought that there is just one magma chamber, right underneath the volcano’s crater. However, recent maps have shown that in fact there are three more other significantly sized chambers, located at a greater depth below the caldera, and eastwards from the peak.
Two of them are at 3 to 8 miles beneath sea level, whereas the third one positioned right below the original one is approximately 9 to 25 miles under sea level. This third section is actually much broader, covering several miles to the east, and it appears that it’s sending magma to the chamber located above it.
The pools of molten rock were identified as researchers from the United States Geological Survey were conducting a $3 million analysis of Mount St Helens’ magmatic plumbing. Their purpose had been to detect potential clues regarding the following major eruption.
Geologists had used controlled detonations around the composite volcano, taking into account the fact that seismic waves move at a lower velocity through plasma and liquid, than through hard rock. That is how they managed to achieve a more accurate cartographic representation of the insides of Mount St Helens.
They have also come to the conclusion that in fact all the 4 chambers are interdependent and connected to one another, which means that changes in pressure from molten lava in one area have a direct impact on the other sections as well.
As magma travels across these chambers, the solid rocks eventually crack, and this leads to small earthquakes. When the volcano’s plumbing system bursts open and molten lava injects through it, long-duration seismic movements called harmonic tremors appear.
The more earthquakes build up in frequency, the more the flow of magma increases. This is how the catastrophic eruption of May 18, 1980 initially signaled its approach.
It was by far the most destructive and lethal volcanic event recorded in the history of the United States, causing 57 people to die, and wrecking 47 bridges, 250 homes, 185 miles of highway and 15 miles of railways.
Minor eruptions accompanied by low magnitude earthquakes and ash plumes were also detected between 2004 and 2008, as a new lava dome formed and broke apart.
It is hoped that this recent discovery will allow researchers to understand much better how magma pressure builds inside Mount St. Helens, as molten lava passes from chamber to chamber.
Especially if this high-risk volcano shows more signs of activity, additional information could be collected so as to predict next eruptions much earlier and more precisely than before.
The findings were presented at 2015 Geological Society of America Annual Meeting, which took place in Baltimore, Maryland, between November 1 and 4.
Since this recent study only investigated the volcano at depths of 25 miles, further research will be conducted now at 50 miles beneath the crust.
It appears that lately there have been small tremors suggesting that lava might be traveling upwards, so geologists will be keeping a close eye on Mount St. Helen. After all, a violent eruption would have the potential to generate large ash clouds, which could block out the sun like in a nuclear winter.
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