PEMETAAN MIKROZONASI AREA SUMUR MINYAK TUA DESA BENDOHARJO, GROBOGAN, JAWA TENGAH BERDASARKAN PENGUKURAN MIKROSEISMIK

ANNISA FITRI, Drs. Imam Suyanto, M.Si

2015 | Skripsi | S1 GEOFISIKA

Telah dilakukan pengukuran mikroseismik di daerah sumur minyak tua Desa Bendoharjo, Grobogan, Jawa Tengah dengan tujuan memetakan karakteristik dinamis lapisan tanah permukaan, seperti frekuensi resonansi dan faktor amplifikasi, menggunakan seismometer short period Lennartz 3D Lite dengan frekuensi sampling 80 Hz. Penelitian dilakukan di grid 2 x 3,5 km dengan 40 titik pengukuran. Analisis data dilakukan menggunakan metode Horizontal to Vertical Spectral Ratio (HVSR). Hasil penelitian menunjukan bahwa nilai frekuensi resonansi berkisar 3 -22 Hz; faktor amplifikasi berkisar 0,8 - 5,6; ketebalan lapisan lapuk adalah 3 - 30 m; indeks kerentanan seismik berkisar 0,1 -2,9; dan percepatan getaran maksimum berkisar 8 - 23 gal.

Geophysical study by applying microseismic method has been conducted in order to generate a microzonation map, consisting the dynamic soil and rock propeties such as resonant frequency and amplification factor in an old-well area in Bendoharjo, Gabus, Grobogan, Central Java, using one short period seismometer Lennartz 3D Lite with 80 Hz sampling frequency. The research area covers a grid of 2 x 3.5 km with 40 measurement points. Processed data from GEOPSY by applying HVSR (Horizontal to Vertical Spectrum Ratio) method shown that resonant frequency ranges from 3 - 23 Hz with amplification factor 0.83 - 5.6. Thickness of weathered soil ranges from 3 - 30 m. Seismic susceptibility index ranges from 0.1 - 2.9. And peak ground activity ranges from 8 - 23 gal.

Kata Kunci : mikroseismik, HVSR, indeks kerentanan seismik, percepatan getaran tanah maksimum.