Layered crustal anisotropy around the San Andreas Fault near Parkfield, California

Steep-dip seismic imaging of the shallow San Andreas fault near Parkfield.

Seismic reflection and refraction images illuminate the San Andreas Fault to a depth of 1 kilometer. The prestack depth-migrated reflection image contains near-vertical reflections aligned with the active fault trace. The fault is vertical in the upper 0.5 kilometer, then dips about 70 degrees to the southwest to at least 1 kilometer subsurface. This dip reconciles the difference between the co...

Crustal Strain Near the Big Bend of the San Andreas Fault: Analysis of the Los Padres-Tehachapi Trilateration Networks, California

Low-velocity damaged structure of the San Andreas Fault at Parkfield from fault zone trapped waves

[1] We used dense linear seismic arrays across and along the San Andreas Fault (SAF) at Parkfield, California to record fault zone trapped waves generated by explosions and microearthquakes in 2002. Prominent trapped waves appeared at stations close to the SAF main fault trace while some energy was trapped in the north strand at the array site. Observations and 3-D finitedifference simulations ...

Accelerating and spatially-varying crustal uplift and its geomorphic expression, San Andreas Fault zone north of San Francisco, California

Source Duration Scales with Magnitude Differently for Earthquakes on the San Andreas Fault and on Secondary Faults in Parkfield, California

We used a comparison of source time function pulse widths to show that a group of earthquakes on the San Andreas fault near Parkfield have a constant duration over a magnitude range of 1.4–3.7. Earthquakes on secondary faults have an increase in duration with magnitude, which is the expected relationship for the usual observation of constant stress drop. The constant duration suggests that faul...