A Renewed Look at the Coseismic Surface Deformation and Fault Slip of the 1994 Northridge Earthquake Using Space Geodesy.

摘要

The January 17, 1994 M6.7 Northridge earthquake occurred in the densely populated suburbs northwest of Los Angeles, California, causing 33 deaths and ∼;We measure the coseismic deformation of this earthquake using InSAR data from the ERS-1 and JERS-1 satellites, combined with GPS measurements (Hudnut et al., 1996) that together show uplift of ∼42 cm. Using these data, we first employ a nonlinear inversion to determine the parameters of a best-fitting model using rectangular, uniform slip dislocations. Our best-fitting fault solution contains two faults, a main fault with 2.3 m of slip and a secondary fault to the northwest with 0.8 m.;In detail, however, the deformation pattern of the Northridge event is more complex than can be described by rectangular dislocations. To investigate this, we solve for a detailed slip distribution for the event using a non-planar triangular element fault mesh modified from the SCEC Community Fault Model (Plesch et al.,2007). This model shows a main asperity on a protrusion on the fault, with peak slip of ∼2.7m, bounded at its western edge by a geometrical barrier, a steep down-dip parallel lateral ramp in the fault. Secondary slip of about 0.6m to the northwest of this feature is also present. These two slip patches together shows that the geometry of the fault strongly influences the slip pattern of the event.