Surface slip associated with the 2004 Parkfield, California, earthquake measured on alinement arrays

Although still continuing, surface slip from the 2004 Parkfield earth-quake as measured on alinement arrays appears to be approaching about 30-35 cm between Parkfield and Gold Hill. This includes slip along the main trace and the Southwest Fracture Zone (SWFZ). Slip here was higher in 1966 at about 40 cm. The distribution of 2004 slip appears to have a shape similar to that of the 1966 event, but final slip is expected to be lower in 2004 by about 3-15 cm, even when continuing slip is accounted for. Proportionately, this difference is most notable at the south end at Highway 46, where the 1966 event slip was 13 cm compared to the 2004 slip of 4 cm. Continuous Global Positioning System and creepmeters suggest that significant surface coseismic slip apparently occurred mainly on the SWFZ and perhaps on Middle Mountain (the latter possibly caused by shaking) (Langbein et al., 2005). Creepmeters indicate only minor (