November 17, 2008

HPWREN: An Important Aid to Earth Strain Monitoring

By Duncan Agnew and Frank Wyatt -- UCSD/SIO

We are operating an array of longbase laser strainmeters at three locations in the HPWREN area:

  • Pinyon Flat, where we run three of these 1/2-mile-long instruments and many others; this is a location for collaborative measurements of many geophysical parameters.

  • Durmid Hill, where we run two strainmeters within a kilometer of the San Andreas fault.

  • South of Salton City, where we have installed and operate two strainmeters with funds from the Plate Boundary Observatory initiative of the NSF Earthscope project, which also supports one of the two Durmid Hill systems.

    The purpose of these instruments is to measure how the Earth deforms over time, and especially before and after earthquakes. Reliable realtime data are essential, for two reasons: These data provide a unique measure of how the Earth deforms over the full period-range of hours to months; unusual changes in this deformation would be cause for concern, and conversely, a lack of changes mean that other unusual phenomena (as are reported at times) are not being caused by earth deformation. Roughly once a year we have been able, thanks to having realtime data, to affect discussions that have a potential impact on public safety.

    For these complex instruments, which are both large and very exposed to the elements, realtime data are crucial to keeping them running consistently. We check the realtime data at least daily; the access provided by HPWREN facilitates us in making assessment and adjustments remotely, lowering costs and greatly improving quality.

    HPWREN has provided easy data access to all these sites, for which commercial access would be somewhere between very costly and unavailable. For our projects the benefits of HPWREN have translated directly into lower cost and improved performance. These cost savings have flowed directly to NSF in the case of the three strainmeters just completed as part of the NSF Earthscope program.

    View of the longbase strainmeters near Salton City -- showing the junction of the long evacuated pipes for the two instruments. The HPWREN telemetry-antenna is evident on the end-building.

    Main HPWREN web site (includes information for acknowledgments/disclaimers and feedback/contact)