The following is a finite difference simulation of a Mw6.7 earthquake located on the southern Hayward Fault. The red lines show the locations of major Bay Area faults. The earthquake initiates at the southern end and ruptures toward the north. The color shows the amplitude of waves in meters per second.
Blues indicate negative amplitudes and the reds indicate positive amplitudes.
The asymmetry of the wavefield is due to three-dimensional geologic structure, which has been incorporated in this simulation. Note that the largest amplitudes occur along the portion of the Hayward Fault where the earthquake rupture takes place and in the San Pablo Bay where sedimentary rocks in the model amplify the ground motions. The movie shows 48 seconds of the wavefield. Even after 48 seconds the ground motions in the San Pablo Bay remain quite large. In comparison the length of time for the fault to rupture was 11 seconds.