The detection and location capabilities of large aperture seismic arrays (LASA in Montana and NORSAR in Norway) were determined on the basis of the Detection Logs, Summary Bulletins and NOAA-ERL Preliminary Determination of Epicenters. Estimates of signal and false alarm distributions indicated that LASA can detect on the average 120 seismic signals a day and NORSAR about 35. The probability of detection of an event was estimated for LASA and NORSAR as a function of distance and magnitude.
A method of obtaining theoretical estimates of the location capability of an array as a function of beam resolution, phase type, and slowness, dT/dΔ, is described. Theoretical estimates of the array's location capability compared to observed estimates imply that the arrays are operating close to their expected limits.