Spatial and Temporal Distribution of slip for the 1992 Landers, California, Earthquake
Wald DJ and Heaton TH. 1994. Spatial and Temporal Distribution of slip for the 1992 Landers, California, Earthquake. Bulletin of the Seismological Society of America. 84(3):668-691
We have determined a source rupture model for the 1992 Landers earthquake (M_W 7.2) compatible with multiple data sets, spanning a frequency range from zero to 0.5 Hz. Geodetic survey displacements, near-field and regional strong motions, broadband teleseismic waveforms, and surface offset measurements have been used explicitly to constrain both the spatial and temporal slip variations along the model fault surface. Our fault parameterization involves a variable-slip, multiple-segment, finite-fault model which treats the diverse data sets in a self-consistent manner, allowing them to be inverted both independently and in unison. The high-quality data available for the Landers earthquake provide an unprecedented opportunity for direct comparison of rupture models determined from independent data sets that sample both a wide frequency range and a diverse spatial station orientation with respect to the earthquake slip and radiation pattern. In all models, consistent features include the following: (1) similar overall dislocation patterns and amplitudes with seismic moments of 7 to 8 × 10^(26) dyne-cm (seismic potency of 2.3 to 2.7 km^3); (2) very heterogeneous, unilateral strike slip distributed over a fault length of 65 km and over a width of at least 15 km, though slip is limited to shallower regions in some areas; (3) a total rupture duration of 24 sec and an average rupture velocity of 2.7 km/sec; and (4) substantial variations of slip with depth relative to measured surface offsets. The extended rupture length and duration of the Landers earthquake also allowed imaging of the propagating rupture front with better resolution than for those of prior shorter-duration, strike-slip events. Our imaging allows visualization of the rupture evolution, including local differences in slip durations and variations in rupture velocity. Rupture velocity decreases markedly at shallow depths, as well as near regions of slip transfer from one fault segment to the next, as rupture was also relatively shallow (less than 10 km) in this region.
- Type
- Journal Article
- Authors
- Wald, David; Heaton, Thomas
- Units
- DEVA
- Keywords
- Acceleration, Analytic, California, Death Valley National Monument CA, Death Valley National Park CA, DEVA, Displacements, Earthquakes, Elastic Waves, fault planes, Faults, Geodesy, geologic sketch maps, Geometry, GRBIB, ground motion, Landers earthquakes 1992, Models, Propagation, Rupture, San Bernardino County CA, seismic moment, seismograms, Serial, Strike Slip Faults, synthetic seismograms, teleseismic signals, United States