The Pacific Infrasound Event of April 23, 2001
SCIENCE APPLICATIONS INTERNATIONAL CORP MCLEAN VA
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For the past several years, the Defense Threat Reduction Agencys DTRA Center for Monitoring Research CMR in Arlington, Virginia, has been developing and testing software to extend the International Data Centre nuclear explosion monitoring system to include infrasound monitoring of the atmosphere. This system can form infrasound-only events, or form fused events using any combination of infrasound, seismic, and hydroacoustic data. Evaluation of the performance of the infrasound processing system is hampered by the scarcity of major infrasound events. On April 23, 200, a significant infrasound event occurred, providing a good test case for the system. Signals from this event, subsequently confirmed by optical observations to be a bolide impact over the Northern Pacific Ocean, were recorded on a number of infrasonic arrays in North America and Hawaii. Using arrival information from several International Monitoring System IMS infrasound arrays, an acoustic-only event was built automatically as part of standard event processing at the Prototype International Data Center PIDC. After optical confirmation it was determined that the infrasound and optical locations differed by 3 minutes in origin time and 80 km in location, which is within the estimated error of the infrasound location. This paper presents the Prototype IDC analysis of this event and the subsequent studies undertaken at CMR to refine the hypothesized source location and evaluate the infrasound processing system.
- Seismic Detection and Detectors