| The lava dome in the crater of Mount St. Helens apparently is growing and moving slightly northward, a top volcano scientist said today. "There seems to be some movement in the lava dome," Jeff Wynn, chief scientist at the U.S. Geological Survey's Cascade Volcano Observatory in Vancouver, Wash. The pressure could come either from a buildup of gases within the 8,364-foot mountain, which erupted with devastating force 24 years ago, or from molten rock moving into the dome, Wynn said. Seth Moran, a seismologist at the observatory, estimated the initial movement at 4 centimeters, about an inch and a half. Wynn said the movement "sort of suggests that we're getting closer" to an eruption that could hurl rocks and ash a few thousand feet into the air. He emphasized that the estimates were highly preliminary and inexact because there is only one measuring device on the dome. He estimated scientists will need about 48 hours to interpret the data more clearly. |