August 15, 2005

NEES Liquefaction Experiment Uses HPWREN for Real-Time Data Communications

Extreme ground shaking during earthquakes can dramatically decrease the stability of saturated soils to the point where the soil becomes a viscous fluid. This behavior, called liquefaction, can cause severe damage to buildings and other structures as their foundations can slide or unevenly settle.

A groundbreaking collaborative experiment was initiated last week to help gain a better understanding of the nature of earthquake ground motion mechanisms. The experiment is being sponsored under the National Earthquake Hazards Reduction Program (NEHRP) by both the U.S. Geological Survey (USGS)/NEHRP External Grants Program (USGS Grant number 04HQGR0073) and the National Science Foundation (NSF)/NEHRP-George E. Brown Jr. Network for Earthquake Engineering Simulation (NEES) Program (NSF award number CMS-0402490).

The NEES program includes 15 geographically distributed major earthquake engineering experimental research facilities that are integrated through a unique IT infrastructure. The NEES components utilized in this experiment are the mobile laboratory from the NEES@UTexas facility, and the Wildlife Liquefaction array experimental site from the NEES@UCSB facility.

NEES@UTexas specializes in dynamic field testing using large-scale shakers. The focus of NEES@UCSB is on permanently instrumented field sites for monitoring ground motion, ground failure, liquefaction, and soil-foundation-structure interaction.

WLA site

NEES@UTexas personnel have been shaking the NEES@UCSB Wildlife Liquefaction Array site, located south of the Salton Sea in California's Imperial Valley. NEES@UTexas is using the Tri-Axial Mobile Shaker, which is also known as "T-Rex." Data is being recorded on temporary sensors deployed by NEES@UTexas as well as the permanent array at the site operated by NEES@UCSB.

Data and the video feed are sent to UC Santa Barbara in real-time via a collaborative effort between NEES@UCSB and the NSF funded High Performance Wireless Research and Education Network (HPWREN) program based at UC San Diego.

The data being collected over a two week period will help us improve our understanding of pore pressure generation during ground shaking. This unique data set will be used for years to come by researchers and their students developing and improving ground motion simulation techniques that include the effects of pore pressure. On the link below is a jpeg image of the pore pressure response that we see building up on the NEES permanent field site transducers when "T-Rex" shakes the site.

A web site for the project with a bit more information can be found at http://nees.ucsb.edu/projects/utexas-2005

WLA data

This experiment is a great example of multi-agency and multi-disciplinary collaboration addressing important scientific problems. The combined resources of these different agencies and institutions are able to accomplish far more than would be possible by individual participants alone.

A controllable camera is located at the Wildlife Liquefaction Array (WLA) site for telepresence viewing. Viewing the site to watch the experiment in action is facilitated by the http://tpm.nees.ucsb.edu/localvideo/ web site at UC Santa Barbara.

Participant Web Links:

  • http://erp-web.er.usgs.gov
  • http://www.nees.org
  • http://hpwren.ucsd.edu
  • http://nees.utexas.edu
  • http://nees.ucsb.edu

    Jamison H. Steidl, Associate Research Seismologist, Institute for Crustal Studies, UC Santa Barbara

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