'Megaquakes' Cause Volcanoes to Sink into the Earth

Earthquakes can cause devastation in their wake, leveling buildings, creating tsunamis and even opening cracks in the Earth. Now, scientists have found out something else that "megaquakes" can do. These massive earthquakes can move mountains, causing volcanoes to sink into the ground.

In 2010 and 2011, two earthquakes struck Chile and Japan. These quakes, aside from causing massive damages, also caused several big volcanoes to sink up to 6 inches into the ground. It's a first time for a string of volcanoes to suddenly drop--as far as the scientists are aware.

In order to actually make these findings, the researchers used satellite data to look for deforming ground around the volcanoes before and after the massive 2010 magnitude 8.8 Maule earthquake in Chile and the 2011 magnitude 9.0 Tohoku earthquake in Japan. They were actually searching for signs of increased volcanic activity, but instead found that the volcanoes seemed to have sunk slightly after the earthquakes.

"The observations are so similar in both places," said Matthew Pritchard of Cornell University in an interview with Discovery News. "It's just a spectacular observation."

So what actually caused the volcanoes to sink? The scientists aren't sure. There are two different theories from the two different teams that conducted this study independently. One team believes that the seismic shaking uncorked fissures and fractures that released pent-up hydrothermal fluids at the volcanoes. As the fluids escaped, the ground settled and sank. The other group theorizes that magma chambers under the volcanoes sank more than the surrounding region. The hot rock is weaker and deforms more in response to the crustal changes caused by earthquakes, which could explain the sinking, according to LiveScience.com.

While the findings are certainly interesting, though, sinking volcanoes probably aren't that unusual. It's more likely that we've just observed it for the first time rather than it being a bizarre phenomenon. Currently, the scientists plan to comb through satellite data in order to find more instances of sinking, which could allow them to determine exactly what mechanism causes the volcanoes to fall.

"These remarkable observations highlight that large earthquakes cause significant changes in volcanic regions and may therefore influence volcanic hazard," said Sigurjon Jonsson, a geologist at King Abdullah University of Science and Technology, in an interview with Discovery News.

The findings are published in the journal Nature Geoscience.