XMM1
Middle Mountain Creepmeter

Electronics for this instrument were changed on
March 7, 1996. Scale factor to coverting DCP counts
to RL slip in mm was changed from 142 to 133. Cleaned
data below has this change included; However, there
may be a slight offset in the data which has not
necessarily been taken-out.


The Sept 28, 2004 Parkfield Earthquake caused the wire to
stretch beyond the limits of the micrometer. (ie, the meter 'pegged')
Released tension on wire by feeding 68mm from the anchor end; Micrometer
read -0.7mm

It appears the both the 'Big Creep' counter gauge and electronics
worked through the EQ.


Examination of the differences between the micrometer and telemetry
values indicate that the calibration of this meter is not correct.
In particular, the data from 1993 to 1996 (and perhaps the period 
between 1986 and 1988) indicate a mis-calibration. The equipment change
in 1996 is documented above. Finally, the post-Parkfield EQ data
indicate another change in calibration; but there was no equipment
change. We will investigate this, soon.

Sept-October 2005; The wire had lots of friction due to that 6 inch diameter
conduit pulling apart from slip on the fault; the
pull-apart allowed for the soil to cave-in and covered the wire. 
The wire was replaced and the conduit was patched.

May 2007; swap-out electronics and DCP for a new version; Telemetry 
voltage range now 0-5v; scale factor is now 147 counts(mv) per mm 
fault slip (creep).

Note ---  (Aug 2022)  The data from ~June 2021 and the present suggest
that site is not detecting creep --- rate has been 0mm/yr -- expect something
like 10 mm/yr rate; essentially, the last "good" data is from 2019.
 
Possible times of Offsets;
N 201403202140 Wire reset (AS)
N 201504010250 Wire reset (AS)
N 201603222230 Wire reset (AS)
N 201701261800 Ditto
N 201705040000 Ditto 
N 201804032140 Ditto
N 2019j1020040 reset (JOL)
S N 2021j1690500 reset (TLE)  offset is done in fixitXMR+ script  let out 26 mm of wire (30 mm slip)


For more information, please consult:
Open-File Report 2024-1011, “Summary of Creepmeter Data from 1980 to 2020—Measurements Spanning the Hayward, Calaveras, and San Andreas Faults in Northern and Central California” https://pubs.usgs.gov/publication/ofr20241011

and
Open File Report 89–650, "Catalog of creepmeter measurements in California from 1966 through 1988" https://pubs.usgs.gov/publication/ofr89650

Many people have contributed to this project including:
Roger Bilham
Robert Burford
Sandy Schulz
Andy Snyder
Kate Breckinridge
Todd Erickson
Rich Liechti
Vince Keller
John Langbein

For questions, contact John Langbein (langbein@usgs.gov)