ALBERT

Description: Abstract: The Potsdam network comprises nine (or, including its local sub-net around the station Moxa, 12) seismological stations. It covers an area of some 250 km x 450 km with various subsurface and signal-to-noise conditions. Its center which is connected to the stations by dedicated and/or dialed telephone lines for data transmission, has recently been equipped with 16-bit PCs and peripheral units for digital data acquisition, processing, storage and communication. Selected examples of data processing are given. This large-aperture network provides good conditions for signal detection, phase correlation, as well as event localization and magnitude classification. The detection thresholds of both single stations and the network as a whole without and with noise filtering for improved signal detection have been determined and are compared with data for global seismological networks and some array stations. Up to about 9000 km distance the detectability threshold of the Potsdam network is only about 0.1-0.5 magnitude units higher than that of the NORSAR array of the global network of data exchange as proposed by the Geneva group of scientific experts (GSE), respectively, when all possibilities for signal processing are exploited. Within central Europe, the network detects and locates events with magnitudes between 1 and 3. Because of the large aperture of the station network, its localization accuracy is better than that of the NORSAR or the Graefenberg array. It can be further improved by taking systematic mislocation errors into account. Then, for a global sample of 164 events, the mislocation by the Potsdam network was less than 3.8 degree in 90% of cases (less than 2 degree for 68.3% of events)