Some volcanoes 'scream' at ever-higher pitches until they blow their tops
Sunday, July 14, 2013 - 12:30
in Earth & Climate
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.