XXX Magma Chamber deep under Merapi?

November 7, 2010, by Ken Jorgustin

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merapi-volcano-magma-chambers


Given the recent attention and interest of the Merapi volcano in Indonesia that has been erupting since 26-Oct-2010, it may be of interest to discover some of the details of its magma chamber.

In fact, there apparently is not just one magma chamber underneath Merapi, but quite likely two chambers, one of them possibly being triple size XXX the volume of the other.

A shallow magma chamber is approximately located between 1.5 km and 2.5 km beneath the surface. This is the magma chamber that has delivered most of the eruptive materials during most of its eruptive history.

The average size explosive eruption has been a VEI 2, meaning the magma chamber is probably in the vicinity of  10 million cubic meters (the total amount typically ejected during a VEI 2 eruption).

However, it may be that a larger and deeper magma chamber is feeding the upper shallow chamber.


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A study by Francois Beauducel from the Department of Seismology of the Institut de Physique du Globe de Paris, reveals that there is a larger deep magma chamber located 8.9 km beneath the surface whose chamber may be three times the total volume of the one above it.

The findings are derived from GPS displacements and tilt observations.

A magma conduit channel measuring 20 meters in diameter extends from the chamber to about 1 km beneath the Merapi summit.

A illustration from the study depicts some of the reasoning.

A PDF of the study can be downloaded here.

merapi-volcano-magma-chamber-study-by-francois-beaudecel


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The Merapi volcano first started erupting during October 26, 2010. The eruption has been the largest there in 100 years.

Unfortunately more than 150 people have lost their lives by pyroclastic flows and ash, as it continues. The volcanic ash has reached altitudes of 40 to 50 thousand feet causing restricted air travel and cancellations, while several hundred thousand people have been evacuated nearby.

Surely this ash will travel the globe, having reached into the stratosphere. The question is, how long will it go on and how bad will it get.

The Merapi volcano is one of the most active volcanoes in the world, regularly produces pyroclastic flows, it has been active for 10 thousand years, and is considered to be very dangerous.



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