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Published July 11, 2002 | public
Journal Article

A satellite geodetic survey of large-scale deformation of volcanic centres in the central Andes


Surface deformation in volcanic areas usually indicates movement of magma or hydrothermal fluids at depth. Stratovolcanoes tend to exhibit a complex relationship between deformation and eruptive behaviour. The characteristically long time spans between such eruptions requires a long time series of observations to determine whether deformation without an eruption is common at a given edifice. Such studies, however, are logistically difficult to carry out in most volcanic arcs, as these tend to be remote regions with large numbers of volcanoes (hundreds to even thousands). Here we present a satellite-based interferometric synthetic aperture radar (InSAR) survey of the remote central Andes volcanic arc, a region formed by subduction of the Nazca oceanic plate beneath continental South America. Spanning the years 1992 to 2000, our survey reveals the background level of activity of about 900 volcanoes, 50 of which have been classified as potentially active. We find four centres of broad (tens of kilometres wide), roughly axisymmetric surface deformation. None of these centres are at volcanoes currently classified as potentially active, although two lie within about 10 km of volcanoes with known activity. Source depths inferred from the patterns of deformation lie between 5 and 17 km. In contrast to the four new sources found, we do not observe any deformation associated with recent eruptions of Lascar, Chile.

Additional Information

© 2002 Nature Publishing Group. Received 30 April 2002; Accepted 27 May 2002. European Space Agency (ESA) remote-sensing satellite (ERS) synthetic aperture radar (SAR) imagery for this study was acquired as a Category 1 research project from the ESA. We thank A. Linde for a critical review, L. Rivera and R. Lohman for modelling software, S. de Silva for an electronic version of his volcano database, andH. Zebker, Y. Fialko, P. Segall, E. Brodsky and M. Battaglia for useful discussions. This material is based upon work partially supported by the National Science Foundation under a grant to M.S. M.E.P. was partly supported by NASA and NSF fellowships.

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