9512201 Kanamori This grant provides partial support (48%) for the costs of acquisition and installation of state-of-the-art digital seismographic stations in southern California. Each station consists of a broadband Streickeisen (STS-2) seismometer, a force balanced accelerometer, and a 6 channel 24 bit Quanterra Inc. data logger. Five new stations are planned. This instrumentation can measure seismic waves from small and large earthquakes as well as from teleseisms and regional earthquakes accurately and completely. The new proposed instrumentation complements the existing network of broadband seismographic stations, called TERRAscope. Currently, TERRAscope consists of 17 stations. The new instrumentation will significantly increase the spatial resolution of TERRAscope by reducing current station spacing of 150 km by tens of kilometers within the central part of the network. Currently, most existing earthquake data for Southern California are of limited dynamic range or are measured over very narrow frequency bands and thus their usefulness for general research is limited. Furthermore, pre-TERRAscope instrumentation was not calibrated with sufficient accuracy to provide quantitative amplitude data. The location of these instruments in southern California provides the additional benefit of being able to record large California earthquakes on scale and study their source physics in unprecedented detail. The type of research and research training to be conducted will be fundamental seismological studies of earth structure and earthquake physics, as well as training of Ph.D. candidates and postdoctoral fellows in observational and theoretical seismology. Examples of the projects that will be carried out using the new data are: 1) determination of the structure of the core mantle boundary; 2) imaging of the Pacific-North America plate boundary in southern California; 3) studies of earthquake source physics of both teleseisms around the world and regional earthquakes in the Western US, 4) new theoretical and computational methods for modeling the seismic data will be developed. This project will benefit from existing and other proposed projects at Caltech related to the earthquake monitoring effort. The Pacific Bell foundation (CalREN) is providing digital data transmission at no cost. Other projects are providing software support and data processing facilities. The Data Center of the Southern California Earthquake Center located at Caltech and the IRIS DMS will distribute the data to the seismological research community via INTERNET. ***
