November 2015 – WASHINGTON – 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 meter) 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 U.S. history, have discovered a second enormous magma chamber buried far beneath the surface.
The researchers also believe a second neighboring volcano – Mount Adams – may also be fed from the deeper magma chamber. 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. –Daily Mail
Multiple magma chambers found below volcano: Scientists have released the first results of a pioneering, $3 million study of the plumbing below Mount St. Helens, and they shed light on how the volcano may have erupted in 1980. The study has found three more magma chambers, or reservoirs, below and east of the peak. Scientists before had only been able to confirm one immediately below the crater, though they had suspected the existence of the others. The findings, released Tuesday, show the volcano’s plumbing system is far more complex than geologists thought and that the molten rock that fueled the 1980 explosion may have come from much deeper underground. And it didn’t have a straight path to the surface.
Instead, as earthquakes cracked solid rocks, the magma may have twisted and turned between three different pools of magma. So far, researchers think they’ve identified four magma chambers in the vicinity of the summit: the previously known small chamber right beneath the crater; two chambers 3 to 8 miles below sea level; and one larger chamber 9 to 25 miles below sea level that extends as far east as the Indian Heaven Wilderness. Researchers said there’s still no evidence yet that the big pool of molten rock fuels other volcanoes, such as Mount Adams or Mount Rainier.
Three of the chambers appear to be connected, though, because earthquakes that occurred before and during the 1980 eruption moved up along the edge of the biggest magma chamber and into the upper chamber below the mountain, Rice University geophysicist Alan Levander said. This understanding could help scientists better track rising magma the next time the volcano acts up. “If the mountain ever wakes up again, we could put out more informative statements about why things are happening,” U.S. Geological Survey researcher Seth Moran, a collaborator on the project, told The Daily News on Thursday.
Results of the study were released by Levander in Baltimore at a meeting of the Geological Society of America. He presented the first images of a study launched last fall to map the underground terrain under the volcano. Part of the study involved detonating 23 explosive shots around the mountain, then tracking how the shock waves traveled through the earth. Because one type of seismic waves moves more slowly through liquid than solid rock, scientists could map the suspected pockets of molten rock. –The Columbian