XGH1 Gold Hill Creepmeter Site subject to temp-related diurnals Electronic data feed started drift from LVDT calibrations between 5/16/14 & 9/10/15 and is questionable since then; Re-calib. needed; In April 17, 1998, site was visited and it was observed that the invar wire had slipped off the rocker arm. The wire was restored to its proper place. However, when reconciling the micrometer measurements in May 98 with a measurement in November 97, these measurements implied a 0.3 MM Left lateral movement; the telemetry data implied a 1.5 mm left lateral movement. Thus, it is BELEIVED that the telemetried data showing the large LL motion between Dec 97 and April 98 is BOGUS; The offset shown is late April in the data below was installed to force the telemetried values equal to the micrometer measurements; Later complilations of this data may have the data from Dec 97 through late April deleted. June 8, 2004; Noted that recent (last few years) of micrometer and telemetry data seem to be inconsistant with original calibration of 134 cnt/mm-RL slip. Performed a calibration of the instrument by sliding wire on anchor end and measuring displacement on micrometer and collecting the DCP counts; Calibration confirms original results. Sept 28 2004 Parkfield EQ--- site stayed on scale November 2006 swap-out electronics and DCP for a new version; Telemetry voltage range now 0-5v; scale factor is now 146 counts(mv) per mm fault slip (creep). Nov 28, 2006 -- revised scale factor by 3% after comparing digital data to aperiodic micrometer measurements. The archival data reflects this change in scale factor April 1, 2014 -- revised scale factor by 50% after comparing digital data to aperiodic micrometer measurements. The archival data reflects this change in scale factor Data after Jan 2019 is probably bad due to lack of maintenance. 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)