PERFORMANCE-TEST ON LONG-PERIOD MOMENT TENSOR DETERMINATION FOR NEAR EARTHQUAKES BY A SPARSE LOCAL-NETWORK

We have investigated the accuracy of long-period moment tensor determination for local to regional earthquakes by a sparse local network consisting of three stations equipped with a very-broad-band, three-component seismometer. We present the analysis results for 15 events with seismic moments of 3 x 10(17) to 9 x 10(19) Nm, which occurred in and near the Japanese region during the period from January to December of 1989. The moment tensor solutions obtained for the events are compared with the solutions retrieved from global networks and reported in PDE (Preliminary Determination of Epicenters). The comparison shows that a sparse local network of three-component, very-broad-band seismomenters can reliably determine the moment tensors of near-distance, moderate to large events.