Bilqis El Farsiyyi, Mochamad Aryono Adhi, Nugroho Budi Wibowo, Desi Mustami' Limayukha, Elsa Fadlika Widyantari, Ilqia Rahma, Rahmania Sofyana Ulya

Identification of Seismic Vulnerability in Sleman Regency Based on Site Effect Analysis Using Microtremor Data

Introduction

Identification of seismic vulnerability in sleman regency based on site effect analysis using microtremor data. Analyze seismic vulnerability in Sleman Regency using microtremor data & HVSR method. Identifies earthquake-prone zones based on site effects, dominant frequency, and amplification factors with GIS.

Abstract

Yogyakarta is a province in the southern part of Java Island which is close to volcanoes. In this area there are sedimentary materials, such as silt, sand, tuff, breccia, agglomerate and conglomerate so that they are at risk of being affected by local site effects when an earthquake occurs. This study aims to determine earthquake vulnerable zones in several areas in Sleman Regency, including Berbah, Kalasan and Prambanan Districts based on site effect analysis with dominant frequency parameters (f0), amplification factor (A0) and seismic vulnerability index (Kg) using micro seismic data with data of 27 points which are then processed using the Horizontal to Vertical Spectral Ratio (HVSR) method and micro zonation using Geographic Information System (GIS). The results of data processing show that the site class in Sleman Regency is divided into 3, namely SD (Medium Soil), SC (Very Dense Soil) and SB (Rock). Areas with rock formations with soft soil structures are the most vulnerable areas to earthquakes. The lowest

Review

This study, titled 'Identification of Seismic Vulnerability in Sleman Regency Based on Site Effect Analysis Using Microtremor Data,' addresses a critical issue of seismic hazard assessment in a geologically complex and seismically active region. The authors aim to delineate earthquake vulnerable zones within specific districts of Sleman Regency, Yogyakarta, a province characterized by diverse sedimentary materials and proximity to volcanoes. The objective of determining local site effects, a significant contributor to earthquake damage, is highly relevant for urban planning, infrastructure development, and disaster risk reduction strategies in such an exposed area, particularly given the region's known seismic activity. The methodology employed for this analysis is robust, utilizing microtremor data collected from 27 points and processed through the well-established Horizontal to Vertical Spectral Ratio (HVSR) method. This approach allows for the estimation of key parameters such as dominant frequency (f0), amplification factor (A0), and seismic vulnerability index (Kg), which are essential for characterizing site response. The subsequent integration of these results into a Geographic Information System (GIS) for microzonation is a practical and effective way to visualize and communicate spatial variations in seismic vulnerability. Preliminary findings indicate the presence of three distinct site classes—SD (Medium Soil), SC (Very Dense Soil), and SB (Rock)—with the crucial, albeit somewhat enigmatic, conclusion that 'areas with rock formations with soft soil structures are the most vulnerable areas to earthquakes.' While the study presents a sound methodological framework and addresses a highly pertinent topic, a more complete understanding of its findings is hindered by the truncated abstract. The statement regarding 'rock formations with soft soil structures' being most vulnerable requires further elucidation, as it likely refers to specific geological conditions, such as shallow soft soil layers overlying bedrock, which are known to amplify seismic waves. A full presentation of the f0, A0, and Kg values, especially those identified as 'lowest' in the incomplete sentence, would be crucial for a comprehensive evaluation of the results. Future work should elaborate on the mechanisms driving vulnerability in the identified zones, potentially comparing these findings with historical earthquake damage patterns or integrating them directly into local building codes and urban development plans to maximize their societal impact. Despite the limitations of the provided abstract, the study promises a valuable contribution to regional seismic hazard assessment.

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