ANALYSIS AND AUTOMATIC PROCESSING IN NEAR-FIELD OF 8 1992-1994 TSUNAMIGENIC EARTHQUAKES - IMPROVEMENTS TOWARDS REAL-TIME TSUNAMI WARNING

We study eight tsunamigenic earthquakes of 1992-1994 with data from single near-field 3-component long-period stations. The analysis is made from the standpoint of tsunami warning by an automatic process which estimates the epicentral location and the seismic moment through the variable-period mantle magnitude M(m). Simulations of early warning based on the real-time computation of the seismic moment are also tested with this system, which would give a justified warning in each region of tsunami potentiality. By exploiting the dependence of moment rate release with frequency, the system has the capability of recognizing both ''tsunami earthquakes'' such as the 1992 Nicaragua and 1994 Java events, as well as instances of the opposite case of low-frequency deficiency, interpreted as indicating a deeper than normal source (1993 Guam event). We report both the results of delayed-time processing of the near-field stations, and the actual real-time warnings at PPT, which confirm the former.