Compilation and analysis of displacement measurements obtained on the Superstition Hills fault zone and nearby faults in Imperial Valley, California, following the earthquakes of November 24, 1987

Abstract

FIGURE 1. Index map showing the location of the SHFZ and the two epicenters of the November 1987 earthquakes. Surface rupture along the SHFZ and the northeasttrending faults are shown schematically (from Sharp et al 1989). FLOW CHART field notes for lip measurements slip data files 'SITE'.DAT S J N prior parameter files 'SITE'.OUT slip parameter files 'SITE'.OUT 1 plots of data and model fits for slip sites intermediate parameter tables 'GROUP'.TBL 'SITE'R.TBL TABLE 1. Format of the 'SITE'.DAT file, shown by NQUAD.DAT, required by the QUAD3D program.

Surface Slip Associated with the 2004 Parkfield, California, Earthquake Measured on Alinement Arrays

“…The amount of afterslip before then cannot be precisely determined for that 6-day gap. Two days before our initial survey, slip on cracks in the Highway 46 asphalt was estimated at Յ0.5 cm (M. J. Rymer, personal comm., 2004), but across the continuous GPS network near the lat- Budding et al, (1989). † Event slip (main trace only) is the value of slip calculated from the AFTER function § for the time at which the inferred rate of afterslip (i.e., the slope of the AFTER function § ), equals the background rate of interseismic slip as shown in the table.…”

“…Parameter b is the inverse of the power-law duration (b ‫ס‬ 1/T), where T is the time period during which surface slip follows the power law, and c is the power-law exponent. The program employs Monte Carlo simulation to make error estimates of the constants u f , b, and c (for code see Budding et al [1989]). The term u f , or final slip, however, is probably a misnomer for the Parkfield arrays, where the expected resumption of large interseismic creep rates precludes the afterslip curve from ever terminating in the asymptotic form assumed for the program.…”

Long‐Term Afterslip of the 2004M 6.0 Parkfield, California, Earthquake—Implications for Forecasting Amount and Duration of Afterslip on Other Major Creeping Faults

“…Fortran code for AFTER was supplied by J. Boatwright (U.S. Geological Survey [USGS], Menlo Park, California); the documentation and the code are available in Budding et al (1989) at http://pubs.usgs.gov/of/1989/ 0140/report.pdf (last accessed March 2017). Fortran code for Omori4, a program by J. O. Langbein to fit afterslip data to the MOL of Langbein et al (2006), was supplied by J. O.…”

“…For purposes of forecasting final slip, we used the AFTER program Budding et al, 1989) to invert postseismic slip observations (i.e., differential displacement between two sides of the fault), obtaining best-fitting coefficients for an empirical afterslip relation (1) that fits afterslip observations for continental strike-slip earthquakes well: E Q -T A R G E T ; t e m p : i n t r a l i n k -; d f 1 ; 3 1 3 ; 4 9 7 ut u f = 1 T t c 1 (Aagaard et al, 2012). Displacement, u accumulates with time t, in days following the earthquake, toward a final value u f (in cm), which includes coseismic and postseismic afterslip; in which T may be described as the duration, or the time for which this relation behaves as a power law with exponent c. After time T, the afterslip continues but at a lower rate while approaching u f asymptotically.…”

Proceedings of conference XLV; a workshop on Fault segmentation and controls of rupture initiation and termination

“…(For extrapolated slip amounts at 1 day and final slip see Fig. 4 A and Budding et al, 1989. ) Dashed line represents approximate 12-day cumulative right slip summed for the north and Imler strands and the extensions of the strands beyond the area of maximum slip crossover.…”