Recent earthquakes in Japan and Chile caused several volcanoes located on land, parallel to the coastlines of Japan, Chile and Argentina, to sink, report two studies published online this week in Nature Geoscience. Similarities in the observations at both earthquake locations imply that this phenomenon could be widespread.
In two unrelated studies, Youichiro Takada and Yo Fukushima, and Matthew Pritchard and colleagues, used satellite data to analyse the deformation of Earth’s surface caused by the 2011 magnitude 9.0 Tohoku earthquake in Japan and the 2010 magnitude 8.8 Maule earthquake in Chile, respectively. Following both quakes, volcanoes situated nearby to the ruptured faults subsided by up to 15 cm. The sinking in Japan was probably caused by subsidence of magma reservoirs and hot, weak rocks beneath the volcanoes, whereas the sinking in Chile was probably caused by a release of hydrothermal fluids from beneath the volcanoes.
In an accompanying News and Views article, Sigurjon Jonsson writes that “Although consensus on what caused the volcanoes to sink has not been reached, these remarkable observations highlight that large earthquakes cause significant changes in volcanic regions and may therefore influence volcanic hazard.”