Hi all, I'm up early working on text for a long-suffering manuscript. Thought the draft of the paragraph below might be of interest. (dextral means right-lateral on some plane; Holocene is about last 11 thousand years, Quaternary is about last 2 million years. One question would be whether or not the GPS data are showing the areas most likely to have frequent earthquakes......in many cases, the answer is "yes", but it could be misleading in others (????). Don't worry, I won't post my whole paper here....it would be nice to post a figure or 2 but I don't have time and it would hurt publication chances....Chris

The San Andreas Fault defines the dextral boundary between the Pacific and North American plates. Yet, in southern California, GPS data indicate that the combined slip on the southern San Andreas Fault and San Jacinto Fault is only about ~70% of the plate motion, with the San Andreas Fault carrying as little as 30% north of its junction with the San Jacinto fault (Meade and Hager, in press?). Trenching studies at Wrightwood show that, in the last ~1500 years, the rate of right slip is more than twice the GPS slip rate in this area (Weldon et al., 2004). This discrepancy is related to a rate of geodetically-determined dextral shear in the Eastern California Shear zone that is several times higher than the Quaternary and Holocene geologic rates (Refs**..Oskin….Rockwell). GPS data indicate that 30% of plate motion is carried as right-lateral slip on NW-SE faults distributed across almost 300 km southwest of the San Andreas, including almost 10% on faults located west of San Nicolas Island, over 120 km offshore southwest of the Los Angeles mainland (Dixon……Beavan….**). One of the most dramatic ideas being developed by scientists who participate in the Southern California Earthquake Center is that there are strain transients, and that GPS-derived velocities are not consistent with Quaternary or Holocene geologically-derived rates.