International Seismological Datacenter. Automatic Association of Long Period Surface Wave Data

摘要

An automatic procedure for association of surface waves to defined seismic events is presented. A signal is accepted as associated to an event if the observed arrival time falls within a specified time window around the theoretical arrival time. The theoretical arrival times are calculated from the origin time of the event and the theoretical travel times of the waves from the event to the recording stations. Surface waves are assumed to follow great circle paths. The procedure was tested on surface wave data from a four day period giving good results. About two thirds of all reported surface wave signals were associated and about half of all events were assigned a surface wave magnitude. This magnitude was estimated by using observed signal values and, from stations without observed signals, actual noise values. The event magnitude estimated in this way compares with the station magnitudes and turns out to be a good method of verification of the associations.