Top of lava dome falls into St. Helens crater

03 July 2005 | 12:45 Code : 5305 Geoscience events
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A large chunk was knocked off the growing lava dome on Mount St. Helens Saturday, sending an ash plume above the crater rim, the U.S. Geological Survey reported.
A large chunk was knocked off the growing lava dome on Mount St. Helens Saturday, sending an ash plume above the crater rim, the U.S. Geological Survey reported.

A rockfall at 6 a.m. caused what scientists called a "substantial seismic signal" and knocked the piece off the lava dome. Despite persistent smaller rockfalls, the volcano was relatively quiet for the rest of the day.

The U.S. Geological Survey and the University of Washington have monitored the volcano closely since it rumbled back to life Sept. 23, with shuddering seismic activity that peaked above magnitude 3 as hot magma broke through rocks in its path. Molten rock reached the surface Oct. 11, marking resumption of dome-building activity that had stopped in 1986. On March 8, it shot ash higher than 30,000 feet, but since then has maintained low-key activity, with wispy smoke regularly floating from the crater.

Scientists have said a more explosive eruption, possibly dropping ash within a 10-mile radius of the crater, is possible at any time.

THE ASSOCIATED PRESS

tags: QAZVIN


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