Microzonation efforts of disaster mitigation using mikrotremor refraction method (ReMi) in Kuwu, Grobogan

Abstract

Microtremor refraction is one application of geophysical methods for disaster mitigation microzonation in a region based on dominant frequency value and amplification value. The purpose of this study is to determine microzonation of soil vulnerability index (Kg) from the result of the dominant frequency value (f0) and amplification (A0). This research has been done in the Kuwu of Grobogan District using P.A.S.I Seismograph Mod. 16S24-P and 3D Borehole Geophone Model GFA 60/100. Measurements at each point for 20 minutes and performed for 2 repetitions. The interval of each measurement point is about 350-400 m with a total of 12 points of measurement. Microtremor data processing using Geopsy and Surfer 11 software to create microzonation maps. The result of the dominant frequency value is between 2.14 Hz to 10.26 Hz with an amplification value between 1.47 to 2.40. The value of soil vulnerability index is between 0.23 to 2.20. The location with the highest soil vulnerability index value is at location 5 with a soil vulnerability index value of 2.20.