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: Experiments open window on landscape formation

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

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

Experiments open window on landscape formation

14 hours ago

University of Oregon geologists have seen ridges and valleys form in real time and—even though the work was a fast-forwarded operation done in a laboratory setting—they now have an idea of how climate ...

NASA image: Canadian wildfires continue

14 hours ago

Canada is reeling from an early fire season this year as dozens of fires ravage at least three provinces of the country. All of the following reports are as of July 2, 2015.

The very hungry sea anemone

16 hours ago

The surprising culinary preferences of an abyssal sea anemone have been unveiled by a team of scientists from the National Oceanography Centre (NOC).

How Virginia is preparing for the next quake

20 hours ago

The 5.8 magnitude earthquake that struck the commonwealth in 2011 was a wake-up call for many Virginians. Originating deep under Louisa County, the quake was felt as far north as Canada and caused significant ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.