Bulletin of the Geological Society of Malaysia, Volume 55, November 2009, pp. 67-72
Department of Geology, University of Malaya, 50603 Kuala Lumpur, Malaysia
Email Address: mustaffk@um.edu.my
Abstract— This paper presents the study on the cause of the recent, small and shallow intraplate earthquakes in the Bukit Tinggi area. It discusses the correlation between the earthquake localities and the regional lineaments/structures of the area interpreted from SRTM digital elevation model. The results of the study show that the earthquakes are located at or near to the intersection of three sets of major lineaments trending N-S, NW-SE and NE-SW. This corresponds to the N-S faults, the NW-SE Bukit Tinggi and Kuala Lumpur fault zones and the NE-SW faults, respectively. It is interpreted that the earthquakes are due to the reactivation of the above faults. The fault reactivations are believed to be the result of stress build-up due to the present-day tectonics in SE Asia (Sundaland), especially the oblique, NNE-oriented subduction of the Indo–Australian plate under the Sundaland. The earthquake occurrences indicate that the core of Sundaland is also deforming and that earthquakes do occur in Peninsular Malaysia. It is implied that the intraplate deformation zone associated with the Sumatran Subduction Zone is wide, encompassing Peninsular Malaysia. Hence, it is suggested that the design of large engineering structures in Peninsular Malaysia must take into consideration the possible seismicity due to the reactivation of ancient major faults zones, the seismicity due to tremors from seismic waves generated with epicentres located in Sumatra and rarely, major dam-induced seismicity.
Abstrak— Kertas kerja ini mengemukakan kajian terhadap punca gempabumi intraplat bermagnitud kecil dan cetek yang berlaku baru-baru ini di sekitar Bukit Tinggi. Kertas ini membincangkan korelasi antara kedudukan gempabumi dengan lineamen dan struktur rantau dengan menggunakan model aras digital SRTM. Hasil kajian menunjukkan gempabumigempabumi ini terletak pada atau berhampiran dengan persilangan antara tiga lineamen utama yang menjurus U-S, BL-TG dan TL-BD yang berpadanan dengan zon-zon sesar Bukit Tinggi – Kuala Lumpur serta sesar menjurus U-S dan TL. Ditafsirkan bahawa gempabumi-gempabumi ini disebabkan oleh pengaktifan semula sesar-sesar atas. Pengaktifan semula ini disebakan oleh peningkatan tegasan intraplat berpunca daripada aktiviti tektonik kini di Asia Tenggara (Pentas Sunda), terutamanya subduksi menyerong Plat Indo-Australia ke bawah Sundaland. Maka disyorkan rekabentuk struktur-struktur kejuruteraan besar di Semenanjung Malaysia mesti mengambil kira kesan seismik akibat pengaktifan semula sesar-sesar kuno tempatan, kesan dari gempabumi yang berpunca dari Sumatra dan gegaran akibat daripada pembebanan empangan major tempatan.
Keywords: intraplate, earthquakes, seismicity, lineaments, tectonics, Bukit Tinggi
https://doi.org/10.7186/bgsm55200911
