Perpustakaan Digital ITB

The objective of this paper is to discuss some aspects of the Bengkulu 2007 earthquake which needs to be clarified or explained. A big earthquake of magnitude 8.4 hit Bengkulu on September 12, 2007 at 18;10 (West Indonesian Time). Another big one (an aftershock of the first big one?) hit Bengkulu again at 06;49 the following day, September 13, 2007. Notwithanding the sizes of these two earthquakes the distribution of the damaged areas took a very peculiar form. It is as follows: 1. The destruction inflicted by the two big shocks was practically confined to a very narrow zone or strip along the coast line. Among the slightly damaged buildings or houses there were spots of completely destroyed buildings or houses (completely flattened to the ground).These on the other hand were usually relatively new buildings/houses. 2. The destruction were due to improper engineering design and construction (too heavy roofing), or poor workmanship and the use of very poor building materials. 3. Compared to the June 1914 earthquake of which destruction reached the very end of the Malayan Peninsula, Singapore, Bangka and Belitung, the damages inflicted by the 2007 Bengkulu earthquake were relatively speaking very light. How do we explain this? Next to paying attention to the source zone areas of earthquakes, the Indonesian Gvt. and the society at large should also pay more attention to the local subsurface structures, the preparedness of the people, increasing the quality of the engineering design & construction, improving workmanship in building dwelling houses, and strengthening or retrofitting any dwelling houses in earthquake prone areas. This should be part of the national mitigation program. Ultimately the application of the national program of disaster management. Until today the Gvt has been the one who is responsible for carrying the burden of the reconstruction and rehabilitation program after any disaster. A program of risk transfer by having the insurance industry as a partner of the Gvt is very timely, really implementing the Public-Private Partnership (PPP) principle. Could the Bengkulu 2000 earthquake, the Aceh 2004 earthquake, the Nias 2005 earthquake, the 2007 West Sumatra earthquake, and the Bengkulu 2007 earthquakes be a precursor to a much bigger one in the South, in the area between South Lampung-Sunda Strait-Southern part of West Java? Could one ignore the aftershocks of those earthquake? In that case the earthquake of September 13.2007, which had a magnitude of 8.4, must be considered to be very odd (Is it an aftershock of the 12 September 07 earthquake, or is it a new shock/main shock of a new series of earthquakes which will lead to a new big one. The authors suggest that the earthquakes along the west coast of Sumatra be used as a test area for the EEPAS Earthquake Forecasting concept. An accurate recording, study, analysis of the numerous aftershocks along the west coast of Sumatra has to be done.