XMR1
Melendy Ranch Creepmeter


May  2008 swap-out electronics and DCP for a new version; Telemetry 
voltage range now 0-5v; scale factor is now 140.4 counts(mv) per mm 
fault slip (creep).

July 2010 Conduit cave-in around invar creep wire noticed. Wire "freed-up".

October 2010 Noticed that Creep mechanical bale had been knocked-over
by rodents.  Bale reset and re-alighned.  Resulted in 1mm+ disparity
between micrometer reading and telemetried data. 

Site defunct as of 7/1/14; wire broken/conduit caved due to fault offset;
may be rehabed in the future;

Sept 5, 2018: Site rebuilt with new transducer and carbon fibre rod by R. Bilham and T. Ericksen.
From Sept 2018 through early April 2019, used on site recording; In April 2019, install
GOES telemetry.

-----------------IMPORTANT!!!!!!!!!!------------------------------

NOTE:  For the four year span between 2014 when the original instrument died and Sept 2019,
the site lost "zero".  Using least square regression which simultaneously estimates the
temporal correlations, a long term rate is estimated spanning the interval between 1991 and
Aug. 2019; That way, the new data could be appended to the older data.  This merged
set is available in the data archive, but one needs to be careful with any analysis
that incorporates the interval from July 2014 and Sept 2018
----------------------------------------------------------------- 
          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)