A global digital seismic network called GEOSCOPE, deployed by France [Romanowicz et al., 1984], now has 18 operational stations distributed worldwide (Figure 1). All of these stations are equipped with three-component broadband STS seismometers [Wielandt and Streckeisen, 1982], which are gradually being upgraded to the very broad band (VBB) response, permitting the recording of all data relevant to teleseismic observations from one single data stream [Wielandt and Steim, 1986]. A data center, located at the Institut de Physique du Globe in Paris, is also attached to the network. Its primary task is to produce network tapes for distribution of GEOSCOPE data to users around the world. Data are also available on the CD-ROMs (compact disk-read-only memory) produced and distributed by the National Earthquake Information Center (NEIC), Denver, Colo.