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EarthScope's use of advanced instrumentation permits us to answer some of the outstanding questions in Earth Sciences by looking deeper, increasing resolution, and integrating diverse measurements and observations.

The Salton Seismic Imaging Project (SSIP)

SSIP is an active-source seismic-imaging project to study earthquake hazards and rifting processes in the Imperial and Coachella Valleys of California. An earthquake along the southern San Andreas Fault, with estimated magnitude between 7.2 and 8.1, is believed to be the greatest natural hazard that California will face in the near future. SSIP uses seismic imaging to determine Earth structure near the southern San Andreas fault to better understand how and where earthquakes and strong shaking will occur.

The project, jointly funded by the NSF MARGINS (now GeoPRISMS) and EarthScope programs and the USGS, involves researchers from Virginia Tech, Caltech, the USGS, and Mexican partner institutions CICESE and UABC, Mexicali. An ocean bottom seismometer deployment in the Salton Sea (Scripps Institution of Oceanography and the University of Nevada, Reno) and a land broadband seismometer deployment across the southern Salton Trough (Stanford University) complement the SSIP project. A SSIP information sheet is available from the USGS. For more information about the project visit SSIP or USGS SSIP.

Seismic shots for the active source land lines started on Wednesday, March 2 2011. Deployment teams include over 40 volunteers, mostly students from universities near and far. The volunteers spent a weekend to learn how to install the Texan and RefTek RT130s seismic instruments and how to use hand-held GPS to navigate to deployment sites. The Imperial Valley College kindly provided classroom space to accommodate training. In the three days prior to onset of firing seismic shots, the teams deployed ~2000 Texan single component instruments and over 180 RT130s with 3C geophones. Five staff members from the IRIS PASSCAL Instrument Center (PIC) manage the handling of the land seismic instruments (instrument preparation and programming; data download, etc.). In addition, the OBS teams have deployed 50 OBS instruments along the N-S axis of the Salton Sea and about 40 broadband stations that were installed several months ago are operating and recorded the shots.

Enjoy some SSIP deployment photos (Images courtesy of B. Woodward, IRIS). The teams are overcoming all the interesting activities that come with field work, including flat tires, stuck vehicles, electric fences, airbags deploying on rough roads, mud, sand, and more.


Volunteers mingling before getting organized on the first morning. The 30,000 square foot warehouse serves as home base for the field operations.


Patrick Bastien and Mouse Reusch (of the PIC) show how to deploy and recover the Texans to half the student volunteers. "Don't use the pick when you dig up the Texan!" The other students are off doing GPS navigation exercises.


Basil Tikoff briefing the experiment map on the edge of the Salton Sea during a field trip for the volunteers. The field trip provided an introduction to the region's geology and context for the experiment.


A practice deployment - the piece of black plastic peeking through the dirt in the foreground is the GPS antenna. The car battery, RefTek, and geophone are buried. Development throughout the Imperial Valley means many stations are installed along dirt roads, requiring "stealthy" installations.


Caltech graduate student Angel Olguin installing a three component station.


William Eastman installs a geophone. The handheld GPS receiver verifies the location of the survey stake.


PI John Hole (blue shirt, back to camera) conducting the end-of-day deployment briefing with the field teams.


For other present and past EarthScope field experiments visit: EarthScope FlexArray seismic instrument and Campaign GPS deployments.