USGS
Mount St. Helens Is Waking Up!
News story originally written on October 5, 2004
After remaining quiet for 18 years, Mount St. Helens, a volcano in the Cascade Range of Washington, U.S.A., is showing signs of activity, puffing steam and ash as scientists look for clues to whether we can expect a large flow of lava in coming days.
On September 29th, 2004 an increased frequency of small earthquakes in the vicinity of Mount St. Helens alerted scientists that the characteristics of the volcano were changing. Two days later, researchers flying over the volcano noticed a bulge at the top and cracks along the surface that were as much as several feet wide and perhaps tens of feet deep. Later that day the area with the cracks emitted steam and ash for almost half an hour. The volcano puffed more steam and ash a few days later. Scientists say that a more significant eruption is likely.
But do the belches of steam and ash that are currently coming out indicate that a flood of lava is on the way? Ash particles that have settled on the leaves of trees nearby Mount St. Helens in the last few days may help scientists understand whether the volcano's recent eruptions are coming up from deep within the magma chamber or from near the volcano’s surface. The researchers are looking closely at the mineral composition and the shape of the ash particles for clues. If the ash particles are made of sharp, glassy shards of rock and contain certain groups of elements, then magma is likely rising toward the surface and will eventually erupt. If the ash particles are made of weathered rock dust, then smaller events at the base of the volcano are lifting old rock into the air.
Preliminary analysis of the ash suggests that it came from older rock inside the volcano. That means hot magma was probably not racing toward the volcano's surface on Friday when the ash was released into the air. However, scientists continue their studies to see if the volcano is changing as it spits more ash. The characteristics of the ash may change, signifying magma coming to the surface.
