Surface Fault Slip Associated with the 2004 Parkfield, California, Earthquake

2006/09/01 by M. J. Rymer · 1 voice · 15 citations
Earth and Planetary Sciences · #Earthquake Detection and Analysis #Geological and Geochemical Analysis #earthquake and tectonic studies

paper · doi:10.1785/0120050830

openalex publication_date 2006/09/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/22

Abstract

Surface fracturing occurred along the San Andreas fault, the subparallel Southwest Fracture Zone, and six secondary faults in association with the 28 September 2004 ( M 6.0) Parkfield earthquake. Fractures formed discontinuous breaks along a 32-km-long stretch of the San Andreas fault. Sense of slip was right lateral; only locally was there a minor (1–11 mm) vertical component of slip. Right-lateral slip in the first few weeks after the event, early in its afterslip period, ranged from 1 to 44 mm. Our observations in the weeks following the earthquake indicated that the highest slip values are in the Middle Mountain area, northwest of the mainshock epicenter (creepmeter measurements indicate a similar distribution of slip). Surface slip along the San Andreas fault developed soon after the mainshock; field checks in the area near Parkfield and about 5 km to the southeast indicated that surface slip developed more than 1 hr but generally less than 1 day after the event. Slip along the Southwest Fracture Zone developed coseismically and extended about 8 km. Sense of slip was right lateral; locally there was a minor to moderate (1–29 mm) vertical component of slip. Right-lateral slip ranged from 1 to 41 mm. Surface slip along secondary faults was right lateral; the right-lateral component of slip ranged from 3 to 5 mm. Surface slip in the 1966 and 2004 events occurred along both the San Andreas fault and the Southwest Fracture Zone. In 1966 the length of ground breakage along the San Andreas fault extended 5 km longer than that mapped in 2004. In contrast, the length of ground breakage along the Southwest Fracture Zone was the same in both events, yet the surface fractures were more continuous in 2004. Surface slip on secondary faults in 2004 indicated previously unmapped structural connections between the San Andreas fault and the Southwest Fracture Zone, further revealing aspects of the structural setting and fault interactions in the Parkfield area.

Citations

• Slip on the San Andreas Fault at Parkfield, California, over Two Earthquake Cycles, and the Implications for Seismic Hazard
• Coseismic and Initial Postseismic Deformation from the 2004 Parkfield, California, Earthquake, Observed by Global Positioning System, Electronic Distance Meter, Creepmeters, and Borehole Strainmeters
• Paleoseismic and Postseismic Observations of Surface Slip along the Parkfield Segment of the San Andreas Fault
• San Andreas Fault Geometry in the Parkfield, California, Region
• Surface Slip Associated with the 2004 Parkfield, California, Earthquake Measured on Alinement Arrays

Cited by

• Three-Dimensional Compressional Wavespeed Model, Earthquake Relocations, and Focal Mechanisms for the Parkfield, California, Region
• Slip on the San Andreas Fault at Parkfield, California, over Two Earthquake Cycles, and the Implications for Seismic Hazard
• Coseismic and Postseismic Slip of the 2004 Parkfield Earthquake from Space-Geodetic Data
• Coseismic and Initial Postseismic Deformation from the 2004 Parkfield, California, Earthquake, Observed by Global Positioning System, Electronic Distance Meter, Creepmeters, and Borehole Strainmeters
• The 2004 Parkfield Earthquake, the 1985 Prediction, and Characteristic Earthquakes: Lessons for the Future
• Kinematic Inversion of the 2004 M 6.0 Parkfield Earthquake Including an Approximation to Site Effects
• Rupture Propagation of the 2004 Parkfield, California, Earthquake from Observations at the UPSAR
• Anisotropy in the Shallow Crust Observed around the San Andreas Fault Before and After the 2004 M 6.0 Parkfield Earthquake
• Seismomagnetic Effects from the Long-Awaited 28 September 2004 M 6.0 Parkfield Earthquake
• Recordings of the 2004 Parkfield Earthquake on the General Earthquake Observation System Array: Implications for Earthquake Precursors, Fault Rupture, and Coseismic Strain Changes
• Paleoseismic and Postseismic Observations of Surface Slip along the Parkfield Segment of the San Andreas Fault
• Effectiveness of Hybrid Green's Function Method in the Simulation of Near-Field Strong Motion: An Application to the 2004 Parkfield Earthquake
• Some Key Features of the Strong-Motion Data from the M 6.0 Parkfield, California, Earthquake of 28 September 2004
• San Andreas Fault Geometry in the Parkfield, California, Region
• Reassessment of a Slip Budget along the Parkfield Segment of the San Andreas Fault

Discussions

• ⭐️Surface Fault Slip Associated with the 2004 Parkfield, California, Earthquake, M.J. Rymer et al. (2006), doi.org/10.1785/0120... Available until Sept. 23, 2024 #BSSA (18/n) [bsky, 2 points, 1 comments]

Related

• San Andreas Fault Geometry in the Parkfield, California, Region
• Surface Slip Associated with the 2004 Parkfield, California, Earthquake Measured on Alinement Arrays
• Paleoseismic and Postseismic Observations of Surface Slip along the Parkfield Segment of the San Andreas Fault
• Slip on the San Andreas Fault at Parkfield, California, over Two Earthquake Cycles, and the Implications for Seismic Hazard
• Reassessment of a Slip Budget along the Parkfield Segment of the San Andreas Fault