Plate Tectonics and Seismic Activities in Sabah Area

Kuei-Hsiang Cheng
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Keywords: Arc and Trench System, Tectonic earthquake, Seismic zoning, GM(1,1)model, Seismic potential assessment
A b s t r a c t
Ever since the Pliocene which was 1.6 million years ago, the structural geology of Sabah is already formed; it is mainly influenced by the early South China Sea Plate, which is subducted into the Sunda Plate. However, since the Cenozoic, the Sunda Plate is mainly influenced by the western and southern of the Sunda-Java Arc and Trench system, and the eastern side of Luzon Arc and Trench system which has an overall impact on the tectonic and seismic activity of Sunda plate. Despite the increasing tectonic activities of Sunda-Java Arc and Trench System, and of Luzon Arc and Trench System since the Quaternary, which cause many large and frequent earthquakes. One particular big earthquake is the M9.0 one in Indian Ocean in 2004, leading to more than two hundred and ninety thousand deaths or missing by the tsunami caused by the earthquake. As for Borneo island which is located in residual arc, the impact of tectonic earthquake is trivial; on the other hand, the Celebes Sea which belongs to the back-arc basin is influenced by the collision of small plates, North Sulawesi, which leads to two M above 7 earthquakes (1996 M7.9 and 1999 M7.1) in the 20th century. In Sabah, there is a complete record of earthquake catalog for more than 40 years. The major earthquake affected Sabah area is from the northwest to the southeast of the seismic zone. The present study is based on the 66 earthquakes (M above 3.7) occurred in Sabah areas since 1974. With the use of seismic zoning method, Sabah area is divided into eight seismic zones. The study uses two predictive models, GM (1,1) model and GM (1,1) Verhulst model of Grey Forecasting theory in Grey System Theory, to evaluate these eight seismic potential zones of future earthquakes. The result shows that Sandakan, Semporna and Celebes Sea have reached a critical point of accumulating seismic energy. If any trigger factor appears, there is a high possibility for moderate to heavy earthquakes to occur. Additionally, there will be high earthquake potential in Lahad Datu, Tawau, Kudat, Ranau, Tarakan and Sitangkai within the next seven years (2015-2022). Possible disaster reduction is needed.


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