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

Site Classification Based on Shear Wave Velocity from H/V Curve Inversion in Prambanan Subdistrict, Klaten Regency for Earthquake Risk Mitigation

Introduction

Site classification based on shear wave velocity from h/v curve inversion in prambanan subdistrict, klaten regency for earthquake risk mitigation. Prambanan, Klaten earthquake risk mitigation. Site classification uses H/V curve inversion & shear wave velocity (Vs30) to identify B, C, D sites, aiding disaster preparedness.

Abstract

One of the areas that has become a historical tourist attraction in Klaten Regency is Prambanan District. Prambanan District in the south is directly adjacent to Kapanewon Prambanan which has an Opak Fault. This study aims to microzonate earthquake-prone areas based on microseismic parameters using a portable seismograph at 27 measurement points. Data analysis was performed using the Horizontal to Vertical Spectral Ratio (HVSR) method and the ellipticity curve with the help of Geopsy and Dinver software. The results showed that the range of f0 values was between 0.9 and 18 Hz, which was predominantly included in the Type I classification. The A0 values were in the range of 1.2-4 with the size of the distribution of A0 being dominantly low. The value of Kg in this area is classified as low category with a range of 0.1-14. Prambanan District has vs30 values ranging from 234–1260 m/s which are classified into 3 sites namely B, C, and D. The results of this study indicate that Prambanan District has soil with a thick layer of sediment based on information on the distribution of shear wave velocity values to depth 30 meter. These results are relevant as an effort to mitigate earthquake disasters, especially in vulnerable areas such as Prambanan which has a history of seismic activity due to the presence of the Opak Fault.

Review

This study presents a crucial microzonation effort in Prambanan Subdistrict, Klaten Regency, a region of historical significance and direct proximity to the active Opak Fault. Employing a portable seismograph at 27 points, the authors leverage the Horizontal to Vertical Spectral Ratio (HVSR) method and ellipticity curve inversion, using Geopsy and Dinver software, to derive key seismic parameters. The findings, including f0 values predominantly classified as Type I (0.9-18 Hz), low A0 values (1.2-4), and low Kg values (0.1-14), contribute valuable insights into the area's seismic response characteristics. Most notably, the determination of vs30 values ranging from 234–1260 m/s allows for a clear site classification into categories B, C, and D, alongside the identification of a significant thick sediment layer. The paper makes a substantial contribution to earthquake risk mitigation by providing concrete site classification data based on robust geophysical methods. The classification of Prambanan into distinct site categories (B, C, D) according to vs30 values is a practical and directly applicable output for engineering design and urban planning, especially for a region with a documented history of seismic activity. The inference of a thick sediment layer based on shear wave velocity distribution to 30 meters depth is particularly important, as such geological features can significantly amplify seismic waves and thus increase ground motion intensity during an earthquake. This detailed characterization forms a foundational dataset for more targeted hazard assessments and land-use planning. While the abstract provides a strong overview of the methods and results, the full paper would benefit from a more explicit discussion on how the H/V curve inversion was specifically utilized to derive the shear wave velocity profiles that subsequently led to the vs30 values and site classifications. Further elaboration on the implications of the identified "thick layer of sediment" in terms of potential seismic amplification and its linkage to the historical seismic activity would enhance the practical impact. Overall, this research delivers critical information for local authorities and disaster management agencies, laying the groundwork for improved earthquake disaster preparedness and mitigation strategies in the vulnerable Prambanan area.

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