[1] MIT, DEPT EARTH ATMOSPH & PLANETARY SCI, CAMBRIDGE, MA 02139 USA
[2] UNIV GRENOBLE 1, GEOPHYS INTERNE & TECTONOPHYS LAB, F-38041 GRENOBLE, FRANCE
[3] PARIS DEF, SOC NATL ELF AQUITAINE PROD, DEPT SISM PUITS, PARIS, FRANCE
[4] UNIV GRENOBLE 1, GEOPHYS INTERNE & TECTONOPHYS LAB, F-38402 St Martin Dheres, FRANCE
[5] UNIV GRENOBLE 1, INST MECAN, MECAN SOLS LAB, F-38402 St Martin Dheres, FRANCE