The Campus Laboratory Collaboration Program


The Campus Laboratory Collaboration (CLC) Program was initiated in 1995, supported by the Office of the UC president, with the intention of mapping seismic hazards at five areas daily visited by a large amount of people: UCSB UCSD, UCR, UCLA, and LLNL. The results of the project have been used to select sites for boreholes with future plans of deploying down hole arrays of seismic instruments and may possible lead to seismic retrofitting of critically located buildings. This Program has improved our understanding of the seismic hazards facing the different campuses as well as providing a template for future work at other critical sites.

Seismic Refraction Survey

At UCSB, we used borehole data available from prior geotechnical investigations to generate a 3-D contourmap of the shallow subsurface. We used this map to identify layers and faults. Using shallow seismic refraction surveys we estimated the location of shallow faults and P- and S-wave velocity structure and correlated the results with the existing geotechnical and borehole data. The seismic sources consisted of a 10 lb sledgehammer and a hydraulic shear-wave generator. The results show that the thickness and S-wave velocity for the quaternary marine terrace deposits reanges between 3-6m and 350-500 m/s. A strong velocity contrast separates this top layer from the second, Miocene, layer which we found to have a velocity of 1500 m/s. The resolution of the method was limited to the upper 30 m. This does not give us data for a third layer. The campus itself is situated of top of a sediment-filled syncline which is expected to display basin amplification effects on a small scale.

Seismic Array

Further studies at UCSB involved the deployment of nine sites on and around the UCSB campus. The location of the sites are as follows: Environmental Health and Safety Building, Old Gym, Childcare Center, Engineering 1 Building, Casitas, Centenial House, Goleta Airpot (Goleta Slough), MATJ, and Figuroa Mountain (Western Transverse Range). The sites were deployed from October 1996 until March 1997 and recorded events in both continuous mode and triggered mode. Raw data was analysed and converted to SEGY format. Specific site amplification results have not yet been determined.

Modal Shaking of Structures

The viability test program for this was performed at UCSB, and involved shaking the Engineering I building.