Earth scientists are laying plans for a two-year study covering a broad area of southwestern Washington to develop a better understanding of how Mount St. Helens gets its supply of volcanic magma.
“The main goal is to understand the plumbing system of the mountain,” said Kenneth Creager, a University of Washington professor of Earth and space sciences who is leading the study. (more…)
It is not unusual for swarms of small earthquakes to precede a volcanic eruption. They can reach a point of such rapid succession that they create a signal called harmonic tremor that resembles sound made by various types of musical instruments, though at frequencies much lower than humans can hear.
A new analysis of an eruption sequence at Alaska’s Redoubt Volcano in March 2009 shows that the harmonic tremor glided to substantially higher frequencies and then stopped abruptly just before six of the eruptions, five of them coming in succession. (more…)
