Potential volcanological applications of the DORIS system. A geodetic study of the Socorro Island (Mexico) coordinate time-series

Abstract

SUMMARY We analysed DORIS data from Socorro Island (Mexico), providing weekly coordinates in ITRF2000 from 1900 to 2006. Careful analysis of this time-series shows horizontal and vertical movements related to recent activity of the Mt. Evermannn volcano. A deflation of the volcano between 1993 and 1996 (–94 mm yr –1 in the N23 ◦ W direction, directly pointing in the direction of the crater summit) is observed. We identify also a clear horizontal discontinuity of 81 mm and a significant change in velocity on 2002 October 3. We use a Mogi formalism to provide constraints from our geodetic results on the successive locations and size of the depletion and inflation sources. Our model is consistent with a deflation source for the period 1993–1996 located beneath Mt. Evermannn at a depth of about 6.2 km below sea level. However, our data constrain only the azimuth and dip angles of the source, which could be located elsewhere along the azimuth of the summit, depth and volume varying linearly with the distance.