No abstract

Seismic event locations obtained by using P and P arrivals may cause g n severe errors because the Earth's crust is laterally heterogeneous. Location .-"4

ilter. Among the worst were human analysts when operating in the *pick everyhingP mode, the deflection detector, and a prediction-error type detector. The uman analyst could, however, improve to be nearly the best if sufficient care as taken. With a modest amount of care, any detector can be modified to perform ell as an element of an operational system and the choice of single channel etector can be made on other grounds than pure detection such as availability or omputation speed.In this report also we outline the features of the existing on-line detector t the SDAC which, in addition to pure detection, also classifies events as pikes, drop-outs, regionals, and teleseisms and calculates a refined start time.

No abstract