Peak Ground Acceleration and Earthquake Intensity Microzonation in Watukumpul, Pemalang Regency

Urip Nurwijayanto Prabowo,Ayu Fitri Amalia,Widodo Budhi

doi:10.31002/ijose.v3i2.1169

Urip Nurwijayanto Prabowo, Ayu Fitri Amalia + Show 1 more

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https://doi.org/10.31002/ijose.v3i2.1169

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Abstract

Watukumpul is located in Pemalang District, Central Java, which is adjacent to the fault seismotectonic line of Baribis fault in the north and subduction area of the Eurasian and Indies-Australian plates in the south. It makes Watukumpul often experiences an earthquake. This study aimed to map the peak ground acceleration calculated using the Kanai equation and earthquake intensity calculated using Wald equations in Watukumpul. This study used historical earthquake data occurred in 1988-April 2018 from the International Seismological Center and microtremor measurements of 33 points. Microtremor data were processed using the Horizontal to Vertical Spectral Ratio method and resulted the predominant period of study area ranged from 0.13 to 0.74 s. The results showed that the study area had a PGA value of 26.93 - 63.25 gal. The intensity calculation showed that the study area has the potential for earthquake damage with an III-IV MMI scale.  Keywords: Kanai, Watukumpul, Intensity, Earthquake

Highlights

Watukumpul is a sub-district in Pemalang Regency, Central Java, located close to the north coast of Java, passed through the Yogyakarta-Semarang seismotectonic transect in the form of the Baribis fault line (Soehaimi, 2008) and subduction zone between the Eurasian and Indo-Australian plates in the south of Java (Ashadi, 2015)
The mapping of earthquake-vulnerable areas was carried out based on Peak Ground Accelerance (PGA) values and earthquake intensity
In the Horizontal to Vertical Spectral Ratio (HVSR) method, the value of the predominant period is determined based on the peak frequency value of the comparison results of the vertical and horizontal component spectrum expressed in the equation as follows (Nakamura, 1989)

Summary

Introduction

Watukumpul is a sub-district in Pemalang Regency, Central Java, located close to the north coast of Java, passed through the Yogyakarta-Semarang seismotectonic transect in the form of the Baribis fault line (Soehaimi, 2008) and subduction zone between the Eurasian and Indo-Australian plates in the south of Java (Ashadi, 2015). The potential of earthquake sources around the Watukumpul area, Pemalang Regency needs more attention so that it is necessary to map vulnerable areas of earthquake damage as a first step in disaster mitigation and spatial planning. The mapping of earthquake-vulnerable areas was carried out based on Peak Ground Accelerance (PGA) values and earthquake intensity. The value of PGA is the largest land acceleration experienced by an area due to the vibration of the earthquake reaching the area (Broptopuspito, 2006). PGA calculations to determine the susceptibility of an area due to an earthquake have been carried out by various researchers using various attenuation equations including the Boore-Atkinson equation, Youngs (Eva, 2016), Kanai (Permatasari, 2016), Mc Guire (Marlisa, 2016), Fukushima-Tanaka (Saputra, 2010)

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