Evaluation of National Seismograph Network detection capabilities. Annual report, July 1994--July 1995: Volume 1

This first annual report presents detection thresholds and probabilities, and location error ellipse projects for the United States National Seismic Network (USNSN) with and without cooperative stations in the eastern US. Network simulation methods are used with spectral noise levels at stations to simulate the processes of excitation, propagation, detection, and processing of seismic phases. USNSN alone should be capable of detecting 4 or more P waves for shallow crustal earthquakes in nearly all the eastern and central US at magnitude 3.8 level. When cooperative stations are added, the network should be able to detect 4 or more P waves from events 0.2 to 0.3 magnitude units lower. Planned expansion of USNSN and cooperative stations should improve detection levels by an additional 0.2-0.3 magnitudes units in many areas. Location uncertainties for USNSN can be improved by adding real-time cooperative stations. Median error ellipses for magnitude 4.5 earthquakes depend strongly on location, but uncertainties should be less than 100 km{sup 2} in the central US and degrade to 200 km{sup 2} or more offshore and sosuth and north of the international boundaries. Close cooperation with the Canadian National Network should substantially improve detection thresholds and location uncertainties along the Canadian border