SENSITIVITY ANALYSIS OF WAVE HEIGHTS OF TSUNAMI FROM MANILA TRENCH,ON OFFSHORE PLATFORMS IN SABAH.

In this paper, the effect of tsunami waves coming from Manila Trench on offshore platforms in Malaysian waters will be studied. Malaysia has always been perceived to be a country safe from the hazards of earthquakes and tsunami as Malaysia is not located within the Pacific Ring of Fire. Therefore, the usual practice in designing offshore structures is to assume the forces induced on the structures due to these tsunami waves are minimal. Local designing standards and codes does not include any suggestions on including tsunami wave impacts in the design. Furthermore, in the year 2004, a 9.3 Mw earthquake occurred outside the Northwest Coast of Aceh, causing tsunamis which caused destruction amounting to US$ 25 million and 68 deaths, in Malaysia, has left questions on the reliability of these offshore platforms. Since then, efforts have been done to study and predict tsunami’s propagation, which includes the developing a local tsunami numerical analysis model TUNA; where previous simulations have shown very satisfactory performance when compared against Cornell Multi-grid Coupled Tsunami Model (COMCOT) and on-site survey results. TUNA-M2, the software used to simulate the tsunami waves, will allow wave heights to be obtained, when it reaches the point of observation. This will be done by incrementally changing the magnitude of the earthquake, thus giving the wave height and the time it reaches the platforms from the time of occurrence. With this wave heights, the tsunami is simulated in SACS a structural analysis software, where the results, in Unity Check (UC), will define the integrity of the offshore platform.