FY 1993

Some observations related to the Flores Island earthquake and tsunami

González, F., S. Sutisna, P. Hadi, E. Bernard, and P. Winarso

In Tsunami '93, Proceedings of the IUGG/IOC International Tsunami Symposium, Wakayama, Japan, 23–27 August 1993, 789–801 (1993)

Documentation of the 12 December 1992 Flores Island, Indonesia earthquake and tsunami is presented in the form of solid earth, oceanographic, and aerial photography data, and preliminary estimates of death and damage. Geodetic estimates of crustal deformation at Maumere and 16-day aftershock distribution are examined and found to be consistent with crustal deformation computations based on the Harvard CMT solution for the main shock. However, computed maximum uplift is insufficient (about 1.5 m) to account for very large tsunami values (12-20 m) observed by the International Flores Island Survey Team. Tsunami data include a tide gage record at Palopo, 650 km north of the epicenter, and aerial photographic survey data, consisting of more than fifteen hundred overlapping images of approximately 300 km of the Flores Island coastline. The first tsunami wave cycle at Palopo is characterized by positive first motion 104 minutes after the main shock, a maximum of 27 cm and minimum of -47 cm, and a period of 69 minutes. Two air photos are presented; these were taken before and after the disaster, and clearly document the total destruction of Kampungbaru, a small village on Babi Island. These photos demonstrate the value of aerial photography in the collection of tsunami data.