Sains Malaysiana 40(12)(2011): 1393–1405

Kesan Gempa 7.6 Mw Padang Indonesia, 30 September 2009

(Earthquake Impacts of the Mw 7.6, Padang, Indonesia, 30 September 2009)

Sri Atmaja P. Rosyidi

Jurusan Teknik Sipil, Universitas Muhammadiyah Yogyakarta, Jalan Lingkar Selatan

55183 Yogyakarta, Indonesia

Tajul Anuar Jamaluddin

Pusat Pengajian Sains Sekitaran dan Sumber Alam, Fakulti Sains dan Teknologi

Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor D.E., Malaysia

Lim Choun Sian

Institut Kajian Bencana Asia Tenggara (SEADPRI-UKM), Universiti Kebangsaan Malaysia

43600 UKM Bangi, Selangor D.E. Malaysia

Mohd Raihan Taha

Jabatan Kejuruteraan Awam dan Struktur, Fakulti Kejuruteraan

Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor D.E., Malaysia

Received: 2 Disember 2010 / Accepted: 16 Mei 2011

ABSTRACT

The earthquake of 30 September 2009, 7.6 MW that strucked the city of Padang, Padang Pariaman and nearby areas in West Sumatra, Indonesia, killed more than 1200 people. Thousands of damaged houses, buildings and infrastructure have been reported with low to severe damage level. This research reports the effect of the Padang earthquake in terms of building damages and landslides that occured in the city of Padang, Padang Pariaman, Pariaman and Agam. Analysis on earthquake effects was carried out based on the geology, geotechnical, building damages and geohazards data collected from various sources and field works in affected areas. Results from field work showed that damages on the building structures in Padang and Padang Pariaman was due to the quality of construction which did not meet the building code and standard requirements, and the effect of geological conditions, i.e., ground amplification on deep layer of alluvial deposit. Some observed damage in the buildings were related to the building location constructed on the fault lines and soil or rock layers discontinuity.  From the site visit, it was found that landslide cases which occurred in Pariaman and Agam after the earthquake were caused by the topography, geomorphology of area and steep slopes. Further studies should be carried out for hazard risks identification and assessment in order to prepare for future earthquakes.

Keywords: Geohazard; geology, ground amplification; landslide, padang earthquake

ABSTRAK

Gempa bumi pada 30 September 2009, dengan kekuatan 7.6 MW yang melanda Bandar Padang, Padang Pariaman dan wilayah Sumatera Barat, Indonesia, telah mengorbankan lebih daripada 1200 orang. Ribuan buah rumah, bangunan dan infrastruktur lain telah mengalami kerosakan tahap ringan hingga teruk. Kajian ini bertujuan untuk melaporkan kesan gempa bumi Padang terhadap kerosakan bangunan dan tanah runtuh yang berlaku pada kawasan Bandar Padang, Padang Pariaman, Pariaman dan Agam. Kesan gempa bumi ini dianalisis berdasarkan data geologi, geoteknik dan impak geo-bencana yang telah dikumpulkan daripada berbagai sumber dan hasil kajian lapangan. Hasil kajian menunjukkan bahawa kerosakan di kawasan bandar Padang dan Padang Pariaman lebih disebabkan oleh kualiti bangunan yang tidak memenuhi piawaian bangunan dan pengaruh geologi kawasan, iaitu berlakunya amplifikasi tanah disebabkan oleh endapan aluvium yang tebal. Kerosakan teruk pada bangunan antara lainnya dikaitkan dengan kehadiran jalur-jalur sesar kecil atau ketakselanjaran pada lapisan bawah tanah. Beberapa kejadian tanah runtuh besar yang berlaku di Pariaman dan Agam adalah disebabkan oleh geologi kawasan, geomorfologi dan morfologi cerun yang curam. Kajian lanjut diperlukan bagi mengenal pasti dan menilai risiko bencana untuk persediaan menghadapi bencana gempa bumi di masa hadapan

Kata kunci: Amplifikasi tanah; gempa Padang; geo-bencana; geologi; tanah runtuh

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*Corresponding author; email: atmaja-sri@umy.ac.id