Nyland Ranch lies at the southernmost end of the 1906 rupture and the location of the fault is bracketed by a dextral kink in the wooden fence caused by surface creep at approximately 7 mm/yr. A subsurface slow earthquake near San Juan Bautista on the San Andreas fault 16 March 2004 was recorded by a Gladwin borehole Tensor strainmeter and by two creepmeters (SJB2 and CONR). The creepmeter (CONR) is installed SE (left) of the driveway shown above.

CONR ( Specifications 36.85499° N  121.54628°W ,  DC-SE#2248 34 mm range, 45° obliquity, 12 m length. Shallow piers. Multidecade creep rate 5 to 7 mm/yr) has recorded the following signal since March 2004. A water pipe broke near the instrument broke 25-26September and it was repaired the following day. The Parkfield earthquake occurred the following day.

The summary data plot for the slow earthquake in March was assembled by Marie Mee and Michael Gladwin.

Nyland Creep data for 11-23 March 2004 may be downloaded by clicking on the following links3.2 Mb Excel file or 448 K tab-delimited four column text, First line is header indicating date/GMTtime/temperature/dextral_mm

The creepmeter was first installed by Bob Nason in 1968 and is the most northernmost point on the central creeping segment of the San Andreas fault.  It has been operated occasionally in a continuous recording mode since then with various transducers. The site was abandoned two decades ago because of annual flooding, and was operated for a few years before and following the Loma Prieta earthquake. Funding was curtailed in 1987 and renewed in Dec 2003.  A submergible low-power creepmeter was installed in February 2004.

We thank Kathleen Manning for allowing us access to this important measurement site.