ESTIMATE OF THE TSUNAMI SOURCE OF THE 1992 NICARAGUAN EARTHQUAKE FROMTSUNAMI DATA

The Nicaraguan earthquake of September 2, 1992 excited large tsunamis which caused significant damage along the Nicaraguan coasts. Some of t he inhabitants felt only minimal shock before the tsunami arrived, ind icating that excitation of short-period seismic waves was very small. Numerical simulation with the initial tsunami source estimated by the seismic data is carried out to study the characteristics of the tsunam i source by comparing the calculated data with the measured data along the Nicaraguan coast. Finding of the comparison shows that the disloc ation of the fault estimated from the measured data is 5.6 to 10.0 tim es larger than that from seismic data. The tsunami source area, which is 200km in length x 100km in width, is used to explain the distributi on of measured tsunami heights along the coast and the wave period as shown in the tide record at Corinto. The effect of rise time on tsunam i excitation indicates a slow process, which corresponds with the seis mic waves. This event falls under the tsunami earthquake category to p roduces anomalously large tsunamis relative to earthquake magnitude.