Rupture process and near-source shaking of the 1965 Seattle-Tacoma and 2001 Nisqually, intraslab earthquakes

We inverted teleseismic data for the 1965 Seattle-Tacoma earthquake slip and rake. The earthquake had 2 asperities of 12 and 16 km2 near the hypocenter with average slip of 2 and 2.8 m respectively (Mo = 9.4 × 1025 dyne-cm; Mw = 6.6). We also inverted strong-motion and teleseismic data for the 2001 Nisqually earthquake. This earthquake had 2 subevents with an asperity area of 45 km2 between 59 and 62 km depth with an average slip of 1.7 m (Mo = 1.7 × 1026 dyne-cm; Mw = 6.8). Shake-maps of peak ground acceleration (PGA) and spectral acceleration (Sa) were generated using a time-domain approach including slip model, site, and basin-depth corrections based on California geology. Corrections reduced the residuals between observed and predicted PGA and Sa. The simulated pattern of shaking from the 1965 earthquake was twice as high as in the 2001 earthquake due to the proximity of the 1965 epicenter to sedimentary basins.