UW Today

July 14, 2013

Some volcanoes ‘scream’ at ever-higher pitches until they blow their tops

Redoubt Volcano's active lava dome as it appeared on May 8, 2009.

Swarms of small earthquakes before a volcanic eruption can come in such rapid succession that they create a signal called harmonic tremor. A new eruption analysis from Alaska’s Redoubt Volcano shows the harmonic tremor glided to higher frequencies, then stopped abruptly just before six eruptions in 2009.