The Tsunami Run-up Assesment of 1977 Sumba Earthquake in Kuta, Center of Lombok, Indonesia

Abstract

A strong earthquake had been occurred on Friday, August 19th 1977 in Indonesia. The earthquake is known as Sumba Earthquake because originated at under the seabed south side of Sumba Island with magnitude Mw 8.3. The earthquake had triggered the tsunami wave, which is propagated toward south side of Sumba, Sumbawa, Lombok and Bali Island. Some post disaster field survey had been conducted immediately to assess the casualty and material losses of disaster. The information of this tsunami disaster is very limited due to the situation in that time. The access of some tsunami disaster locations are very difficult because the lack of transportation facility in that time especially in Lombok, Sumbawa and Sumba Island. This research attempts to conduct again the post tsunami field survey, especially in Kuta Lombok, in order to reveal the spatial distribution of tsunami run-up. The GPS technology was utilized in this survey when identified the height and position of tsunami run-up. Based on the field survey results, the run-up depth is about 1.5 m with the positions are almost close each other. The simulation results show that the tsunami time arrival is about 20∼30minutes. The result of run-up depth is acceptable compare with the field survey result, i.e. 1.6 m depth. The run-up of tsunami reaches about 300 ∼ 800 m inland from the beach line. The run-up of tsunami occurs in the west area of Kuta Beach and the all area of Seger Beach.