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Data Acquisition The Southern California Seismic Network gathers its data from three sources. The primary source of our data consists of a network of over 300 seismic sensors placed throughout Southern California. These continually transmit information to us via a combination of radio and microwave links, T1 lines, a frame relay cloud, and internet links. Another source of data for the SCSN is a subset of shared stations owned and operated by UC Berkeley. These stations use T1 splitters to transmit the data to our servers as well as theirs. Finally, we have agreements with other seismic networks, enabling us to gather their data through client/server software such as Earthworm and Antelope. Once the data enters our network, it is then handled by the Realtime systems. The seismic data is stored on the RT systems in the wavepool (areas on disk and in RAM) for a period of about 21 days. These two servers, working in a primary/shadow model for redundancy, use specialized software to detect seismic events. Once an event has been declared, the systems notify the authorities (via pager or email), and the data center. The data center then archives the waveforms for that event from the wavepool to its permanent data store (a series of commodity RAID servers).