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All Journal Jurnal Penelitian Pendidikan IPA (JPPIPA) INDONESIAN JOURNAL OF APPLIED PHYSICS
Udi Harmoko
Diponegoro University
Agriculture, Biological Sciences & Forestry Astronomy Biochemistry, Genetics & Molecular Biology Chemical Engineering, Chemistry & Bioengineering Chemistry Education Energy Materials Science & Nanotechnology Physics

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Subsurface Instability Characterization Using the Microtremor HVSR Method for Landslide Risk Assessment in Sriharjo Village, Bantul, Yogyakarta, Indonesia Udi Harmoko; Gatot Yuliyanto; Irham Nurwidyanto; Sugeng Widada
Jurnal Penelitian Pendidikan IPA Vol 11 No 12 (2025): December
Publisher : Postgraduate, University of Mataram

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29303/jppipa.v11i12.13313

Abstract

Sriharjo Village, Bantul, Yogyakarta, is affected by recurrent mass movements and slope deformations due to complex geological conditions and groundwater infiltration. This study aims to assess subsurface instability using the Horizontal-to-Vertical Spectral Ratio (HVSR) method. Fifty-three microtremor measurements were conducted along four survey lines, with each recording lasting approximately 20 minutes. The data were processed using Geopsy and Dinver software, employing spectral curve analysis to extract key subsurface parameters. The analysis yielded shear wave velocity (Vs), compressional wave velocity (Vp), Vp/Vs ratio, and Poisson’s ratio. Vs values below 750 m/s indicate soft, less consolidated materials, typically associated with unconsolidated sediments. High Vp/Vs ratios (>2.5) and Poisson’s ratios approaching 0.5 suggest elevated pore water content and low shear strength, indicating saturated and nearly incompressible conditions. Spatial patterns reveal subsurface fluid migration from the north toward the deformation zone, highlighting the role of groundwater infiltration and increased pore pressure in triggering slope instability. This study demonstrates that the interaction between pore pressure and lithological heterogeneity contributes significantly to the development of slip surfaces and ongoing deformation. The findings provide a geophysical framework applicable to slope stability assessment and landslide risk mitigation in vulnerable terrains such as Sriharjo Village.
Analysis of Earthquake Vulnerability of The Demak Coastal Area based on the HVSR (Horizontal To Vertical Spectral Ratio) Method Muhammad Irham Nurwidyanto; Udi Harmoko; Rahmat Gernowo; Gregrius Alvin Fernando; Sorja Koesuma
INDONESIAN JOURNAL OF APPLIED PHYSICS Vol 14, No 2 (2024): October
Publisher : Department of Physics, Sebelas Maret University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.13057/ijap.v14i2.90703

Abstract

Most of the Demak Coastal area, especially on the north coast, has a subsurface structure which is quite thick sediment. The impact of an earthquake will cause damage to subsurface structures and buildings above it, so a method is needed that can determine earthquake vulnerability in an area to take mitigation steps. This research aims to analyze vulnerability to earthquakes based on natural frequency (fo), amplification (Ao) and seismic vulnerability index (SVI). The research was carried out by measuring the microseismic signal response at 89 locations using a 3-component seismograph and data logger. The research results showed that the dominant frequency varied from 0.26 – 5.26 Hz, the amplification factor varied from 0.51 – 3.56 and the seismic susceptibility index varied from 0.14-14.77 micro cm2/s. The study area was classified into low SVI (SVI < 5), medium SVI (5 < SVI < 10), and high SVI (SVI > 10).  The potential earthquake hazard described by SVI with a value range of 10 < SVI (high classification) is found at observation station 60 (Bedono Hamlet) and observation station 70 (Karangwaru Hamlet Cemetery)
Co-Authors Gatot Yuliyanto Gregrius Alvin Fernando Irham Nurwidyanto Muhammad Irham Nurwidyanto Rahmat Gernowo Sorja Koesuma Sugeng Widada