by Arben Pitarka, Nancy Collins, Hong-Kie Thio, Robert Graves and Paul Somerville
Pitarka, Arben, Nancy Collins, Hong-Kie Thio, Robert Graves and Paul Somerville (2006). Implications of Rupture Process and Site Effects in the Spatial Distribution and Amplitude of the Near-Fault Ground Motion From the 2004 Parkfield Earthquake. SMIP06
Seminar on Utilization of Strong-Motion Data, p. 19 - 40.
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The 2004 Mw6 Parkfield earthquake is the last in a series of several strike-slip earthquakes that have
occurred on the same fault located in a zone that marks the transition between a creeping section and a
locked section of the San Andreas Fault in central California. Ground motion data recorded at a dense
network of near-fault stations installed by California Geological Survey (CGS) and United States Geological
Survey (USGS) are unprecedented in terms of quality and characteristics for this type of earthquake in
California. Although of moderate size, the earthquake produced near-fault ground motion acceleration
that exceeds predictions from empirical ground motion models. At three sites the recorded acceleration
was more than 1.0 g (Shakal et al., 2005). Very large peak ground velocities of up to 83 cm/s were also
recorded at both ends of the fault. On the other hand, most of the stations located very near to the
fault recorded ground motion with very low acceleration and velocity. In this study we investigate the
implication of the rupture kinematics and dynamics, and local site effects in the amplitude and spatial
variation of the near-fault ground motion for this earthquake.