Dr. David Schaff
Earth Institute Contact: Dr. David Schaff
We propose to generate a multi-phase detection bulletin derived by two means -- station array processing (multi-station) and source array processing (multi-event). High precision location estimates are expected by appling waveform cross correlation for events that are too small to detect/locate with standard methods based on P-waves. We then will quantify how these array methods improve and supplement the operational procedures used for producing the Reviewed Event Bulletin (REB), which uses single event-station detections for P-waves that have signal-to-noise ratios (STN) above some threshold. In addition to the multi-station and event methods, our experience suggests that using other phases, especially Lg-waves, present many benefits for detecting smaller magnitude events in continental regions as compared to P-waves alone. The primary reason is that Lg-waves typically have the largest amplitude arrivals on regional seismograms.
The experimental detection bulletin will be created for the time period 1995-1999 using the International Monitoring System (IMS) primary and auxiliary networks and compared to the REB. Using the same fixed dataset allows direct comparison of the experimental bulletin with the REB, to see how many new events are acquired, and evaluation of the benefits of the proposed techniques. We shall also compare with denser local and regional bulletins in the vicinity of the Lop Nor test site and within the United States to enable quantification of the lower magnitude detection thresholds achieved by applying multi-station and event methods to available regional phases recorded by the IMS.
Air Force Research Laboratory