2003 Fall Meeting MQUAKE multicast software early warning demonstrated for AU: * Eakins, J A EM: jeakins@ucsd.edu AF: IGPP, SIO, Univ. of California, San Diego, MC-0225 9500 Gilman Drive, La Jolla, CA 92093-0225 United States AU: Hansen, T EM: tshansen@ucsd.edu AF: SDSC, Univ. of California, San Diego, MC-0505 9500 Gilman Drive, La Jolla, CA 92093-0505 United States AU: Vernon, F L EM: flvernon@ucsd.edu AF: IGPP, SIO, Univ. of California, San Diego, MC-0225 9500 Gilman Drive, La Jolla, CA 92093-0225 United States AU: Braun, H AF: SDSC, Univ. of California, San Diego, MC-0505 9500 Gilman Drive, La Jolla, CA 92093-0505 United States AB: MQUAKE distributes real-time multicast parametric information from individual sensors as well as a summarized location and magnitude based on the data recorded from sensors of the ANZA seismic network with the goal of providing event notification prior to arrival of the actual shock wave at the client's location. The program gathers detection and triggering information from an operational Antelope real-time data collection system and sends them to clients via multicast and unicast UDP packets. Multicast packets are preferred as they allow multiple people to receive event packets in the fastest time possible (however, a unicast mode is available since most IP networks do not support multicast). These packets are decrypted in a client software which then produces a list of triggers/events that will be used in future versions of the code to generate wavefront estimate plots and approximate maximum shock wave travel times based on the client's location and limited current information. This systems works in both a wired and wireless environment, such as HPWREN, the High Performance Wireless Research and Education Network. A real-time example of this system was obtained during the Ml5.1 31 October 2001 earthquake that occurred directly under the ANZA seismic network, approximately 70 km away from an MQUAKE client. The MQUAKE program was able to deliver a warning of a significant "event" 10 seconds after the initial ground motion was recorded and about 4 seconds prior to ground motion reaching the client. An actual event location and magnitude approximation was received 71 seconds after the local ground shaking at the client's location (85 seconds after the event). Had the client been located along the coast of San Diego, they would have had additional warning time prior to the shaking. Clients in San Diego, the closest major metropolitan area to this event, could have received up to 12 seconds of early warning.