Seismic Activity Increases at Mount St. Helens



Any eruption would be small compared to the one that dramatically changed the shape of the mountain in May 1980, killed 57 people, destroyed more than 200 homes and flattened acres of evergreen spruce forest.

Small earthquakes were occurring at the rate of three to four per minute, with larger ones of magnitude 3 to 3.3 detected every three to four minutes, the USGS said in a statement. The lava dome that was formed after the 1980 eruption has moved 2.5 inches (6 cm) since Monday.

Any potential eruption would most likely be similar to a minor 1986 eruption that disrupted the lava dome in the volcano's crater, Scott told reporters, adding that the main concern was whether a plume of ash formed and interfered with air traffic.

Ash from the 1980 eruption billowed across North America and was carried as far east as Oklahoma.

"Any time there's ash in the air where there is aircraft, it is a concern," Scott said. Volcanic ash can make aircraft engines stall.

Mount St. Helens is in the southeastern part of Washington state, about 100 miles south of Seattle and 50 miles north of Oregon's largest city, Portland.

Air traffic officials said they were on alert and prepared to divert air traffic in case of an ash-spewing eruption.

Government scientists are also conducting daily helicopter flights over the volcano's horseshoe-shaped crate to try to detect any signs of gases associated with the movement of magma, or molten rock. So far, they reported nothing out of the ordinary.

Seismologists said there was no connection between activity at Mount St. Helens and a strong earthquake near Parkfield, California or a smaller series of quakes in Alaska earlier this week.

The violent eruption of Mount St. Helens on May 18, 1980, blew off the top of the volcano, reducing its summit from 9,677 feet to 8,364 feet.

The lava dome erupted once in October 1986 and strong earthquakes were detected in 1989, when fresh magma entered the volcano's lava system.

This thing is gonna blow. I wonder if bookmakers are taking odds on when. Imagine the news shifting from Florida hurricanes over to NW volcanic activity. Instead of endless pictures of reporters in windbreakers in front of storm-damaged homes, we'll have endless pictures of Northwest parking lots with cars covered in volcanic ash.

SEATTLE (Reuters) - The number of small earthquakes at Mount St. Helens increased on Thursday while the volcano's lava crust shifted further, government scientists said, keeping the volcano's alert status at the second-highest level...


Posted: Fri - October 1, 2004 at 12:44 AM        

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