AUTOMATIC EARTHQUAKE PROCESSING AT THE U.S. WEST COAST/ALASKA TSUNAMI WARNING CENTER

The automatic earthquake processing system developed at the U.S. West Coast/Alaska Tsunami Warning Center, known as EarlyBird, provides the center with fast, reliable, and accurate locations and magnitudes for worldwide, regional, and local earthquakes. EarlyBird automatically and interactively computes MS, Ml, Mb, Mw, and Mwp magnitudes. It provides an easy method for interactive adjustment of automated P-picks and magnitude determinations during an event. For the time period July 2001 through December 2001, EarlyBird automatically located 94% of worldwide earthquakes magnitude 6 or greater (64 of 68) and 100% of Alaska, British Columbia, and U.S. west coast earthquakes over magnitude 5 (34 of 34). Missed events often occurred in the coda of previous events leading to inaccurate automatic P-picks. Locations of earthquakes over magnitude 6 averaged less than 0.7 degrees from the USGS National Earthquake Information Center’s Preliminary Determination of Epicenter reports.