Part of Mount St. Helens' crater has risen an additional 100 feet in the past few days, more evidence of change in the volcano as it enters a new period of activity. Scientists call this uplifted area "the Loaf." It is a fractured zone that underlies glacier ice and part of the crater's lava dome, and it now has risen a total of about 250 feet in the past week, according to the U.S. Geological Survey. Scientists say the deformity is caused by pressure from magma that is fitfully working its way toward the surface and a probable eruption. They say all the events of the last two weeks — earthquakes, harmonic tremors, ash explosions and steaming inside the crater — are likely leading up to such an event.
A substantial drop in earthquake activity prompted scientists to speculate Wednesday that the magma had taken a temporary pause in its rock-breaking journey to the surface. But the Loaf's expansion, detected in overflights later that day, appeared to indicate that magma is still on the move, perhaps with a pathway cleared at least partially by three steam and ash explosions over the past week. "The skids are greased," said Jake Lowenstern, a USGS volcanologist. "It certainly seems like the volcano has found a weak area to push up." |