Let's revist Mt. Merapi

However, let me be clear that I dont' think there are any Easy Answers to any earthchanges!!


Earthquakes lead to increased volcanic activity
Malaysia Sun
Wednesday 11th April, 2007
(ANI)
http://story. malaysiasun. com/index. php/ct/9/ cid/89d96798a395 64bd/id/240773/ cs/1/
(okay. I did try to fix the link, I really did!!)

Washington, Apr 11 : Scientists using NASA satellite data have found strong evidence that a major earthquake can lead to a nearly immediate increase in regional volcanic activity.

The intensity of two ongoing volcanic eruptions on Indonesia's Java Island increased sharply three days following a powerful, 6.4-magnitude earthquake on the island in May 2006. The increased volcanic activity further persisted for about nine days.

"During this period, we found clear evidence that the earthquake caused both volcanoes to release greater amounts of heat, and lava emission surged to two to three times higher than prior to the tremor," said lead author of the study, Andrew Harris, from the University of Hawaii, Honolulu.

While scientists have long debated whether earthquakes can trigger new volcanic eruptions, this study linked an earthquake to enhanced volcanic activity at two ongoing eruptions that were being closely monitored by satellite-based sensors on a daily basis.

At the time of the earthquake, each volcano was being checked for changes in heat output by satellite sensors as part of a routine global "hot spot" monitoring effort that uses near real-time satellite data from NASA's Terra and Aqua satellites.

Maps of worldwide hot spot activity are created with data from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on these satellites, pinpointing locations where surface temperatures are much hotter than their surroundings.

Researchers combined these data with other details about the Indonesian volcanoes gathered by the satellites to analyze temperature and lava output rates at both volcanoes over a 35-day period spanning the earthquake.

They found that the two volcanoes, Merapi and Semeru, which are about 260 kilometres apart and roughly 50 kilometres north and 280 kilometres east of the earthquake epicentre, showed an increase in eruption rate due to underground stresses from the earthquake's seismic waves.

The seismic waves pumped magma -- molten rock beneath the surface -- into the conduit to the surface, increasing eruption rates.

"The responses at Merapi and Semeru lagged about three days behind the triggering earthquake, which may reflect the time it took the change felt by magma residing at deeper levels to be transmitted to the surface," said Harris.

The researchers said that regional earthquake events had sufficient power to modify the intensity of activity at ongoing eruptions, although they may not always be able to trigger new volcanic eruptions.

According to their findings, the Java earthquake had a significant influence on the volcanoes for a relatively short period of several days.

"Eruptions must be closely and continuously monitored in the days immediately before, during and after an earthquake if we are to link any earthquake with enhanced volcanic activity," added Harris.

The research was recently published in the American Geophysical Union's Geophysical Research Letters.