Adree Octova, Mohd Hazizan Mohd Hashim, Tomi Suprianto Simatupang, Heliogina Febriandika, Mulya Gusman, Dedi Yulhendra
This study was conducted in an active limestone quarry in Padang, West Sumatra, Indonesia, to investigate the integrated application of passive seismic and geoelectrical resistivity methods for detecting subsurface cavities and assessing seismic vulnerability. A sinkhole approximately 8 m in diameter was discovered during mining operations, raising concerns about the presence of other undetected voids. To address this, 20 passive seismic measurements were conducted using the Horizontal-to-Vertical Spectral Ratio (HVSR) method to determine dominant frequency (f0) and amplification factor (A0), which were then used to calculate the seismic vulnerability index (Kg). Complementary geoelectrical resistivity surveys were carried out along four profiles—two of 480 m and two of 240 m—covering all seismic points. Resistivity values exceeding 5000 Ωm were interpreted as indicators of air-filled cavities. The results showed spatial variation in Kg, ranging from 0.32 × 10−6 s2/cm to 12.29 × 10−6 s2/cm, with the highest value recorded at SP14, suggesting moderate to significant seismic vulnerability based on existing thresholds. This location also corresponded to a prominent resistivity anomaly. The 2D resistivity sections revealed vertical variations, while a 3D resistivity point-cloud model illustrated the spatial distribution of potential cavities. HVSR curves were superimposed onto the resistivity profiles to visually correlate seismic and resistivity anomalies. The integration of both datasets successfully identified weak zones and enhanced the reliability of subsurface cavity detection. This combined approach provides a robust framework for geotechnical risk assessment in karst environments and supports safer mining operations. © 2025 Elsevier B.V.
Strategic Mineral Niche, School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, Penang, Malaysia; Mining Engineering Department, Universitas Negeri Padang, Padang, Indonesia
