The coseismic geodetic signature of the 1999 Hector Mine Earthquake

The M=7.1 Hector Mine earthquake ruptured the Lavic Lake fault near Twentyn ine Palms, CA at 09:46 UTC October 16, 1999. Because it occurred near the e astern edge of the Southern California Integrated GPS Network (SCIGN), a ne twork of permanent, continuously recording GPS receivers for measuring the crustal deformation field around Los Angeles, CA, it was possible to determ ine the deformation associated with the earthquake with unprecedented speed and reliability. Thirty-four stations recorded displacements over the 3-si gma level. The displacements measured with GPS can be modeled by a fault 46 .2 +/- 2.6 km long, 8.2 +/- 1.0 km wide, striking 330 degrees, dipping 84 d egrees east, with 301 +/- 36 cm right lateral strike-slip, and 145 +/- 36 c m of east-up dip-slip, yielding a potency of 1.3 km(3) and geodetic moment of 3.8 x 10(26) dyne-cm. The trace and dip of the model fault is consistent with the observed ground rupture and seismic focal mechanisms.