Molten rock has been rising inside Mount St. Helens for the past six years, but there’s no telling whether the next eruption is close or far off, federal scientists said Tuesday. There’s no sign, though, of any impending eruption.
Federal officials plan to release a statement Wednesday about the volcano in conjunction with the presentation this week of a paper to the Seismological Society of America in Anchorage.
U.S. Geological Survey volcanologist Seth Moran will discuss how earthquake and deformation studies show how fresh molten rock has been recharging the Southwest Washington volcano since its last eruption, which lasted from 2004 to 2008. The eruption was marked by some minor steam and rock explosions and dramatic growth of the volcano’s lava dome. It caused no damage or injuries.
The finding that fresh molten rock is welling up into the 8,363-foot volcano is no surprise. It’s the process that keeps volcanos perking, said Carolyn Driedger, outreach coordinator and spokeswoman for the USGS Cascades Volcano Observatory in Vancouver.
Wednesday’s statement is meant to help keep the research presentation in perspective and take advantage of a teachable moment, Driedger said.
“There are no signs of an impending eruption. This has been going on for some time. We’re no closer (to an eruption) today than we were yesterday,” Driedger said.
An abstract of Moran’s paper describes how the volcano deflated during the last eruption as molten rock poured out — much like a balloon shrinks as air escapes. Since the eruption ended, the process has reversed, with the volcano inflating as molten rock moves into it and swells it back out.
However, Moran said in his paper, the volcano has been much slower to refuel following the 2004-08 eruption than it was following the eruptive period from 1980-1986. The implications of that are unknown.
The volcano on May 18, 1980, unleashed a massive eruption that killed 57 people, flattened 230 square miles of forest, tore away the top of the peak and sent a cloud of ash around the world.