Global Positioning System (gps), electronic distance meter, creepmeter, and strainmeter measurements spanning the M 6.0 Parkfield, California, earthquake are examined. Using these data from 100 sec through 9 months following the mainshock, the Omori’s law, with rate inversely related to time, 1/tp and p ranging between 0.7 and 1.3, characterizes the time-dependent deformation during the postseismic period; these results are consistent with creep models for elastic solids. With an accurate function of postseismic response, the coseismic displacements can be estimated from the high-rate, 1-min sampling gps; and the coseismic displacements are approximately 75% of those estimated from the daily solutions. Consequently, fault-slip models using daily solutions overestimate coseismic slip. In addition, at 2 months and at 8 months following the mainshock, postseismic displacements are modeled as slip on the San Andreas fault with a lower bound on the moment exceeding that of the coseismic moment.
Online material: Data description and supplementary figures, tables, and data used in models and time-series analysis.