Descr: BBAD would include 4-5 instruments deployed in a dense array in the town of Bombay Beach near the southern terminus of the San Andreas fault, as well as an additional 2-3 instruments deployed within and just outside of the well-developed gouge zone along the fault north of Bombay Beach. This deployment is motivated by an apparently credible prediction (Keilis-Borok et al.) that a large (M>6.5) earthquake will occur in southeastern California before September of 2004. Although the prediction methodology is still under developmental and experimental, the group did predict two earthquakes (in Japan and central California) that have now occurred. It thus appears reasonable to launch a modest instrumental effort that could result in the collection of valuable and unique data, should the 3rd predicted earthquake occur. BBAD focuses near the southern end of the San Andreas fault, arguably the fault most likely to fulfill the prediction and the location at which such a rupture w! ould most likely initiate. The goal of the deployment would be, first, to obtain high-quality, dense array recordings of nucleation, should the earthquake occur not only when but also where it is anticipated. If the prediction is fulfilled by a large earthquake elsewhere in southern California, the BBAD deployment will still offer a good opportunity to record remotely triggered earthquakes. Based on past experience, it is likely that a regional earthquake of M7 or larger will be followed by remotely triggered earthquakes in the Brawley Seismic Zone. Source studies of remotely triggered earthquakes have been difficult because of data limitations, and because these events often occur within the coda of large regional mainshocks. Dense-array recordings of triggered earthquakes would offer a unique opportunity to investigate the source properties of the events. If the predicted earthquake does not occur, it is likely that the instruments will record some data of interest, as the Salton Sea region is one of the most seismically active locations in California. The investment of time, resources, and manpower will moreover have been modest, as only minimal travel and other expenses will be required to service instruments from the PI's home base in Pasadena. BBAD is a gamble, but one that offers potentially terrific bang for the (modest) buck.
