The Sumatra volcano-triggering experiment: Contributions from Space Geodesy

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An open question in volcano science is whether and how earthquakes trigger volcanic eruptions. It is well known that there is a short-term interaction related to the passage of the seismic waves (minutes to days after the earthquake) but it is not understood whether there is an intermediate-term or a long-term interaction (weeks to month or month to decades after the earthquake). This project uses satellite interferometry to survey the volcanic activity in Sumatra before and after the 2004 and 2005 earthquakes to answer this question. The earthquakes were among the largest-ever instrumental earthquakes and provide a unique opportunity to investigate eruption triggering because they were associated with significant decompression of the volcanic arc. The InSAR survey tests the hypothesis that earthquake-induced decompression triggers eruptions. The rationale of this project is that new volcanic activity is associated with the ascent of magma from deep sources towards the surface and thus detectable by precise space geodetic measurements. In the first phase of the project 2005-2010 imagery of the Canadian Radarsat-1 and the Japanese ALOS satellite will be analyzed to detect any anomalous surface deformation that occurred after the earthquakes. In the second phase 1993-1998 imagery from the JERS-1 satellites will be analyzed to map surface deformation prior to the earthquakes. Comparison of pre-earthquake with post-earthquake data will identify triggered volcano deformation. This project is a partnership between the University of Miami and the Institute of Technology in Bandung (ITB), Indonesia. ITB will lead ground-based investigations of satellite-detected active centres in collaboration with Indonesian government and research institutions.