Volcanoes Unrest
Oct 7-9, 2004

USGS responds to Volcano Activity and New Unrest in Alaska, Washington, and Hawaii

Scientists are responding [Oct 7] to several volcanoes in the United States that are erupting or showing signs of restless activity in order to provide up-to-date hazard assessments and warnings of potential eruptions to the public.

 

Mount St. Helens' Crater Floor Rising

Part of Mount St. Helens' crater floor has risen 50 to 100 feet since Tuesday while earthquake rates have been low, signs that magma is moving upward without much resistance, scientists said Thursday. With the latest rising [Oct 7], an area of the crater floor just south of the nearly 1,000-foot lava dome has risen about 250 feet since the mountain began stirring two weeks ago, Lowenstern said. There's no way to tell when magma might reach the surface, he said. On Wednesday, scientists lowered the alert level for the southwest Washington volcano, saying earthquake activity was down to the lowest level since before the mountain started venting steam last week. Despite the new detail Thursday on the magma movement, scientists said there was no reason to raise the alert level back up. Larry Mastin, a USGS expert in the physics of volcano eruptions, said that while there's an outside chance an eruption could send a plume of ash 15 miles into the air or higher, there is no indication that any eruption is imminent or that it would threaten lives or property.

 

Quake Activity Rises at Mount St. Helens

Earthquake activity has increased [Oct 9] at Mount St. Helens, but scientists said Saturday there was no reason to raise the volcano's alert level. Scientists said earthquake activity had been low until Friday, indicating molten rock was moving upward with little resistance. By Saturday, however, quakes of magnitude 2.4 were occurring every one to two minutes, they said.