Surveying Volcanic Arcs with Satellite Radar Interferometry: The Central Andes, Kamchatka, and Beyond
Satellite Interferometric Synthetic Aperture Radar (InSAR) permits both synoptic and detailed surveys of magmatic activity in volcanic arcs. To illustrate this capability, we summarize here the results of an extended study of inferred magmatic activity in the central Andean arc (Pritchard and Simons, 2002; Pritchard, 2003; Pritchard and Simons, 2004), as well as new results from Kamchatka. In the central Andes, encompassing parts of Peru, Bolivia, Chile, and Argentina, we have observed ~900 volcanoes between 1992 and 2003 and found four previously undocumented sources of deformation. Coupled with surveys in other arcs, this deformation indicates that short-lived pulses of magma movement are common, although the relation of these movements to eruptive activity is unclear. In fact, no co-eruptive deformation was detected from eruptions at four other Andean volcanoes. In Kamchatka, the limits of current InSAR satellites are apparent in terms of the quality of the measurements and coverage of the arc. Nonetheless, we observe subsidence associated with a large lava flow that erupted 28 years ago and inflation of a geothermally active caldera. While a global inventory of volcanic arcs is impossible with current datasets, InSAR is a critical tool for understanding volcanic hazard at most of the world's poorly monitored subaerial volcanoes as well as for searching for large magma reservoirs.