Decompression wave caused eruption chain reaction

Oct 29, 2012

The 2010 eruption of Iceland's Eyjafjallajökull proceeded through fits and starts. A new analysis by Tarasewicz et al.suggests that a downward propagating decompression wave triggered a cascade of explosive eruptions from sequentially deeper magma reservoirs. Drawing on detailed seismic measurements, the authors find that earthquake activity under the volcano propagated deeper into the subsurface as the eruption progressed.

They find that at the onset of the explosive phase of the eruption on April 14, magma was ejected from a chamber located 5 kilometers (3.1 miles) below the summit. Over the subsequent weeks, the eruption calmed and the surface deflated as the subsurface magma chamber emptied. The authors suggest that the decreasing mass of the summit caused the pressure in a subsurface pipeline that fed the main magma chamber to drop.

On May 2, a cluster of earthquakes took place at 10-to-13 kilometers (6-to-8 miles) depth. This seismicity was followed a few days later by a sharp increase in rate. Parallel sequences took place on May 10 and May 15, with earthquake swarms located at 19-to-24 kilometers (12-to-15) being followed by increased explosive activity days later.

The authors suggest that the initial drop in pipeline pressure caused a magma-filled sill, located at 10-to-13 kilometers (6-to-8 miles) depth, to become overpressured relative to the pipeline. The caused the rock separating the sill and the pipeline to fracture, leading to the observed seismicity. This fracturing liberated the magma stored within the sill, driving the surge in explosive eruption rate. The authors suggest that this process then cascaded deeper into the subsurface. The emptying sill led the pressure in the pipeline to be reduced even further, causing a second sill at 19 kilometers (12 miles) deep (and, in turn, a third sill at 24 kilometers (15 miles)) to become similarly overpressured, leading to fracturing and eruption.

Explore further: Satellites sees a question mark in Tropical Storm Ana

More information: Geophysical Research Letters, doi: 10.1029/2012GL053518, 2012

add to favorites email to friend print save as pdf

Related Stories

Magma chambers awake sooner than thought

Mar 07, 2011

Until now it was thought that once a volcano's magma chamber had cooled down it remained dormant for centuries before it could be remobilized by fresh magma. A theoretical model developed by Alain Burgisser of the Orléans ...

Possible trigger for volcanic 'super-eruptions' found

Oct 12, 2011

The "super-eruption" of a major volcanic system occurs about every 100,000 years and is considered one of the most catastrophic natural events on Earth, yet scientists have long been unsure about what triggers ...

Volcanic Quakes Help Forecast Eruptions

Dec 22, 2009

Monitoring the earthquakes caused from magma movements inside an active volcano could help to improve the accuracy of forecasting an eruption.

Recommended for you

Asbestos likely more widespread than previously thought

4 hours ago

Naturally occurring asbestos minerals may be more widespread than previously thought, with newly discovered sources now identified within the Las Vegas metropolitan area. The asbestos-rich areas are in locations not previously ...

User comments : 0