KAJIAN KONDISI FISIK WILAYAH RAWAN GEMPABUMI UNTUK PENILAIAN KERENTANAN FISIK BANGUNAN DI KECAMATAN WEDI DAN KECAMATAN GANTIWARNO KABUPATEN KLATEN

SRI MULYATI, Prof. Dr. Junun Sartohadi, M.Sc.; Dr. Djati Mardiatno, M.Si.

2015 | Tesis | S2 MANAJEMEN BENCANA

Kecamatan Gantiwarno dan Kecamatan Wedi merupakan dua kecamatan di Kabupaten Klaten yang mengalami kerusakan terparah di wilayah Provinsi Jawa Tengah akibat gempabumi Bantul 27 Mei 2006. Wilayah penelitian merupakan wilayah yang jauh dari pusat gempabumi namun mengalami kerusakan parah pada bangunan. Penelitian ini bertujuan untuk 1) memetakan tingkat kerawanan fisik wilayah di Kecamatan Gantiwarno dan Kecamatan Wedi, 2) memetakan tingkat kerentanan fisik bangunan tempat tinggal di Kecamatan Gantiwarno dan Kecamatan Wedi, 3) menganalisis hubungan tingkat kerawanan fisik wilayah dengan kerentanan fisik bangunan terhadap bahaya gempabumi. Analisis data mikrotremor menggunakan metode HVSR (Horizontal to Vertical Spectrum Ratio). Titik pengukuran mikrotremor sebanyak 35 titik pada 6 satuan bentuklahan yaitu satuan bentuklahan Fluvial, Fluvial Vulkanik, Fluvial Denudasional, Denudasional, Struktural Denudasional dan Struktural. Penilaian kerawanan fisik wilayah berdasarkan nilai amplifikasi, frekuensi, kedalaman lapisan sedimen dan PGA di batuan dasar. Penilaian kerentanan fisik bangunan dilakukan dengan mengklasifikasikan kerentanan berdasarkan jenis atap bangunan rumah (joglo, limasan dan kampung). Analisis data menggunakan metode kuantitatif. Hasil penelitian menunjukkan bahwa tingkat kerawanan fisik wilayah sangat tinggi berada di Kecamatan Gantiwarno, sedangkan kerawanan fisik wilayah rendah berada di Kecamatan Wedi. Wilayah penelitian memiliki tingkat kerawanan tinggi terhadap gempabumi disebabkan oleh sebagian besar wilayah memiliki satuan bentuklahan Fluvial yang bersifat lunak. Tingkat kerentanan fisik bangunan di wilayah penelitian tergolong tinggi. Hal ini dikarenakan bangunan di wilayah penelitian didominasi oleh rumah dengan tipe atap kampung yang memiliki tingkat kerentanan tinggi. Pola kerusakan bangunan total dan berat berada pada tingkat kerawanan fisik yang tinggi, sedangkan bangunan dengan tingkat kerusakan ringan tersebar pada tingkat kerawanan sedang dan rendah.hal ini menunjukan hubungan antara pola kerentanan bangunan dengan pola sebaran kerawanan fisik wilayah. Kata Kunci: Kerawanan, Kerentanan, Mikrotremor, Bentuklahan

Gantiwarno and Wedi Districts were two districts in Klaten Regency at Central Java Province which suffered most during the earthquake in Bantul on 27 May 2006. The research area was far from the earthquake center, but it had the most severe damage of building. This research aimed to 1) map the level of physical susceptibility in Gantiwarno and Wedi Districts, 2) map the level of residential building physical vulnerability in Gantiwarno and Wedi Districts, 3) analyze the relationship between the level of physical area susceptibility and physical vulnerability of building towards earthquake hazards. The data analysis of microtremor was done by using HVSR (Horizontal to Vertical Spectrum Ratio) method. The spots for microtremor measurement were 35 spots on 6 plots, with the landform of Fluvio, Fluvio Vulcanic, Fluvial Denudational, Denudational, structural and structural denudational. The assessment of physical area susceptibility was based on the value of amplification, frequency, sediment layer depth and PGA in the bed rock. The assessment of physical building vulnerability was done by classifying the vulnerability based on the types of building roof (joglo, limasan and kampung). The data analysis was done in descriptive quantitative. The result of the research shows that the very high level of physical area susceptiblity was in Gantiwarno District, whereas the low level of physical area susceptibility was in Wedi District. The research area had high susceptibility level towards earthquake because most of the area had the landform of fluvial plot that had soft feature. The level of physical building vulnerability in the research area was considered high. This was because the buildings in research area were dominated by house with kampung roof with high vulnerability level. The total and weight of building damage pattern were on high physical vulnerability, while buildings with low damage level were spreading on medium and low vulnerability level. This shows the relationship between the pattern of building vulnerability and physical area susceptibility spreading pattern. Keywords: Susceptiblity, Vulnerability, Microtremor, landform

Kata Kunci : Kerawanan, Kerentanan, Mikrotremor, Bentuklahan / Susceptiblity, Vulnerability, Microtremor, landform