XSC1 Slack Canyon Creepmeter On March 6, 1997, the transducer for this instrument was replaced. The transducer had started to fail in early 1997. In addition, critical micrometer measurements were lost. The tie between the measurements prior to March 6, 1997 is tentative; users should treat the data gap as a potential offset. Around Jan 23, 2007, the DCP and electronics amplifier were changed. Noted that the old electronics, for some reason "saturated" or 'hit the rail' when output of electronic exceeded about 3.7 volts (or the micrometer exceeded 20 mm or so). Inspection of micrometer log reveals that during operation of this instrument, that has never happened. With new DCP and electronics, telemetry voltage range now 0-5v; scale factor is now 119 counts(mv) per mm fault slip (creep). July 1, 2011 -- Recalculate scale factor base upon comparison of digital measurements with aperiodic micrometer measurements. scale factor changed by 4.5%. This is reflected in the arhival data. General Notes: FAULT CREEP DATA FROM PARKFIELD The following data represent real-time measurments of fault slip across the San Andreas fault or its "south-west" trace near Parkfield, CA. Creepmeters consists of 2 piers separated by about 30 meters and connected by an invar wire. The main fault-trace lies between the 2 piers. The wire is at roughly a 30 degree angle from the local trace of the fault. A displacement tranducer measures the change in length of the wire (or the change in distance between the piers). These measurements are made once every 10 minutes and are telemetred to Menlo Park. In addition, micrometer measurements are periodically made by "hand". The telemetred creep data are reconciled with the micrometer measurements. The data have been reconciled with the micrometer measurements and then decimated to daily measurements and scaled to represent fault slip in mm. The data provided here has been processed such that telemetry glitches have been removed, data edited for electronic and other problems, offsets due to resets of the instrument have been removed, and the telemetried data have been reconciled with the Micrometer measurements. Please note that when computing secular rates and other statistics that the assumption of data independence (ie gaussian distributed data) is NOT correct. For starters, the statistics of the data are a mixture of random-walk and white (gaussian) noise. You'll need to construct the appropriate data covariance matrix to account for these noise sources. Otherwise, if you let your standard least squares routine compute the secular rate and its standard error, that error bar will most likely be too small relative to the true estimate of standard error. Because the pier are installed at shallow depths (2-3 meters), these piers will tilt in responce to rainfall. ONE NEEDS TO EXAMINE RAINFALL RECORDS WHEN INTERPRETING THESE CREEP MEASUREMENTS. Many people have contributed to this project including: Robert Burford Sandy Schultz Kate Breckinridge Rich Liechti For questions, contact John Langbein (langbein@usgs.gov) or Andy Snyder (asnyder@usgs.gov)