KAJIAN KARAKTERISTIK DINAMIKA TANAH TERHADAP RESIKO KERAWANAN SEISMIK DAN DAMPAKNYA TERKAIT RENCANA TATA RUANG WILAYAH DI KOTA MATARAM BAGIAN TIMUR

Icha Untari Meidji, Prof. Dr. Sismanto, M.Si.

2014 | Tesis | S2 Ilmu Fisika

Telah dilakukan suatu penelitian mikrotremor di Kota Mataram bagian timur yang terletak di Pulau Lombok. Penelitian ini didasarkan pada kejadian gempabumi dari pemantauan United State Geological Survey (USGS) serta Badan Meteorologi Klimatologi dan Geofisika (BMKG) di Pulau Lombok, terutama di Kota Mataram. Penelitian ini dilakukan untuk mengetahui tingkat kerawanan gempabumi di Kota Mataram bagian timur berdasarkan karakteristik dinamika tanah yang hasilnya dapat untuk perencanaan tata ruang wilayah dengan analisis sebaran nilai periode dominan, ketebalan sedimen dengan menggunakan Vs30 USGS dan inversi eleptisitas, indeks kerentanan seismik (Kg), ground shear strain (γ) dan percepatan getaran tanah maksimum (PGA). Hasil penelitian menunjukkan bahwa di wilayah Kota Mataram bagian timur mempuyai sebaran nilai ketebalan lapisan sedimen berkisar antara 12,8 meter sampai 57,2 meter, sebaran nilai indeks kerentanan seismik berkisar antara 1,65 sampai 22,80, sebaran nilai PGA lapisan tanah permukaan berkisar antara 299,59 gal sampai 850,92 gal dan sebaran nilai ground shear strain berkisar antara 2,41x10-4 sampai 3,56x10-3. Oleh karena itu, Kota Mataram bagian timur teridentifikasi memiliki tingkat kerawanan seismik dengan skala rendah (kategori resiko I, II, III dan IV), sedang (kategori I dan II) hingga tinggi (kategori resiko I). Kecamatan Selaparang memiliki tingkat kerawanan seismik berskala menengah dan dominan tinggi, Kecamatan Cakranegara memiliki tingkat kerawanan seismik berskala menengah dan dominan rendah, serta Kecamatan Sandubaya memiliki kerawanan seismik dengan skala rendah, sedang dan di beberapa lokasi berskala tinggi. Kata Kunci: Mikrotremor, PGA, Vs30, Indeks Kerentanan Seismik, Ground Shear Strain, HVSR, Kota Mataram.

Has been done a research of microtremor in the eastern part of Mataram City in the Lombok Island. This study was based on analysis data of microtremor with additional data from monitoring earthquake occurence by United State Geological Survey (USGS) and boring data in Lombok Island, especially in the city of Mataram. This study was conducted to analyze the vulnerability of earthquakes impact based on the caracteristics of soil dynamics such as the thickness of sediment layer using data Vs30 and elipticity inversion. seismic vulnerability index (Kg), ground shear strain (γ) and the Peak Ground acceleration (PGA) that useful for Urban Land Plan for Mataram’s goverment. The results showed that in the eastern part of the Mataram City has distribution of thickness sediment layer is 12.8 meters to 57.2 meters, the distribution of seismic vulnerability index values ranged from 1.65 to 22.80, the distribution of PGA values of surface soil layer ranged between 299.59 gal to 850.92 gal and distribution of ground shear strain values ranged from 2.41 ×10-4 to 3.56 × 10-3. The Seismic vulnerability map shows that the eastern part of Mataram City has been identified with the scale of the seismic vulnerability from low (risk category I, II, III and IV), medium (risk category I and II) to high scale (risk category I). Subdistrict Selaparang has seismic vurnerability medium scale and high scale, Subdistrict Cakranegara has seismic vurnerability medium scale and low scale, as well as District Sandubaya has seismic vulnerability scale of low, medium and high scale in some locations. Keyword: Microtremor. PGA, Vs30, Seismic Vulnerability Index, Ground Shear Strain, HVSR, Mataram City

Kata Kunci : Mikrotremor, PGA, Vs30, Indeks Kerentanan Seismik, Ground Shear Strain, HVSR, Kota Mataram, Microtremor. PGA, Vs30, Seismic Vulnerability Index, Ground Shear Strain, HVSR, Mataram City