Volcanoes scream before they erupt, according to a new study that researchers conducted when evaluating the 2009 eruption of Alaska’s Redoubt.
They found that as a volcano’s activity changes it starts to emit a steady drum beat of noise, which then increases to a rapid succession of tremors. They then turn into a continuous noise that goes silent before it finally explodes.
These occur as the magma meanders through the cracks inside the volcano. This research now appears in the Journal of Volcanology and Geothermal Research, and was conducted just before Redoubt’s 2009 eruption in Alaska.
New analysis showed that the tremors built to higher frequencies in noise, before it then came to a stop less under a minute before the volcano erupted.
Alicia Hotovec-Ellis, a doctoral student involved in the study, from the University of Washington, noted, “The frequency of this tremor is unusually high for a volcano.”
“Because there’s less time between each earthquake, there’s not enough time to build up enough pressure for a bigger one. After the frequency glides up to a ridiculously high frequency, it pauses and then it explodes.”
The University of Cambridge’s Dr Marie Edmonds, despite not being involved in the study, remarked, “This work is probably the most intensive treatment of this phenomenon. If you can get an idea of what is causing these types of patterns then you have a route to prediction of volcanic eruptions.
She then added, “The question that arises is whether you can ever get these sorts of patterns without an eruption following? We had repetitive sequences of volcanic explosions in the Caribbean island of Montserrat in 1997 and 2003 which were preceded by similar tremors, with hybrid earthquakes that were periodic and then recurrence intervals decreased with time before the explosion. People are converging on a view on how magmas behave.”