DEFORMATION FOLLOWING THE 1994 NORTHRIDGE EARTHQUAKE (M=6.7), SOUTHERN CALIFORNIA

Following the 1994 M-w=6.7 Northridge earthquake, a 65-km-long, north- south array of 11 geodetic monuments was established across the ruptur e. The array was surveyed with GPS ten times in the 4.25 ya after the earthquake. Although there is evidence for modest nonlinear postseismi c relaxation in the first few weeks after the Northridge earthquake, t he deformation in the subsequent four years can be adequately describe d by constant station velocities. The observed S70 degrees E velocity components are consistent with the deformation expected from steady st rain accumulation on the San Andreas fault. The N20 degrees E velocity components indicate that the southern Northridge fault block is movin g almost as a unit N20 degrees E with repect to the northern fault blo ck, the motion being accommodated by a zone of convergence (width 20 k m) at the north end of the Northridge rupture.