NSF EarthScope USArray Transportable Array Catalog and Magnitude Comparisons

One of the responsibilities of the Array Network Facility (ANF) for the Earthscope USArray Transportable Array (TA) seismic network is analyst review of local, regional, and teleseismic earthquakes. As the network traverses the United States, it crosses the authoritative areas of multiple regional networks, which produce their own unique catalog or bulletin of events. Each regional network has its own methods and rules about which magnitude type is calculated and whether station corrections are used. In addition, the seismometers and data acquisition systems vary between (and sometimes within) networks. Since the initial installation of TA stations in 2004, analysts have associated >29,330 events recorded by at least one regional network, as well as located ~15,500 events with more than 10 phase picks where no regional network solution was available, providing over 2.63 million arrivals for >44,830 events. As part of the TA operations, a Richter Ml is calculated for each event observed inside the footprint of the TA. Taking advantage of the consistent and well calibrated TA equipment, we present comparisons of local magnitudes published by each regional network to the standard Ml estimates provided by the TA. The results show in some cases that the TA Ml results are biased when compared to the authoritative regional networks published magnitudes. The observed biases can be caused by the regional networks using different magnitude estimators, different stations, station corrections, path corrections, and/or regional geological settings.