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

Swarms of small earthquakes can precede a volcanic eruption, sometimes resulting in "harmonic tremor" resembling sound from some musical instruments. A new analysis shows tremor during a 2009 sequence at Alaska's Redoubt Volcano glided to substantially higher frequencies, then stopped abruptly just before six of the eruptions.

by via ScienceDaily: Latest Science News