PENENTUAN ZONA RAWAN GUNCANGAN BENCANA GEMPA BUMI BERDASARKAN ANALISIS NILAI AMPLIFIKASI HVSR MIKROTREMOR DAN ANALISIS PERIODE DOMINAN DAERAH LIWA DAN SEKITARNYA

Satria Subkhi Arifin

Abstract


Microtremor is a natural harmonic ground vibration that occurs continuously with low amplitude about 0.1 to 1 micron  by subsurface movements. Microtremor characteristics reflect the characteristics and types of rocks based on the value of the dominant period and useful for analyzing of rocks response in strengthening (amplification ) waves vibration based on the impedance difference between basement and sedimentary rocks above it.

Based on seismicity  historical, Liwa had been hit greatly by an earthquake twice on June 24th, 1933 with  magnitude  7.3 skalarichter  and 7.0 skalarichter on February 15th, 1994, and the degree of damage and the number of victims increases . It underlies the research of microtremor in Liwa on April 15, 2013 to May 4, 2013 that limits in providing information that used for the planology development to decrease the earthquake impact.

The Data result of mickrotremor research were the value of the horizontal to vertical spectral ratio (H/V), the dominant frequency and dominant period. From the analyzing that had been done, it determined that the research area was in area within the value of amplification factor (amplification) was more than  5 and the value of the dominant period was more than 0.5 seconds. Lithology of research area was on alluvial rocks. The interaction of faults made it deformated well and cause the research area was very vulnerable when hit by earthquakes.

Keywords: Microtremor, microzonation, amplification

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References


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