Main Article Content
Abstract
Landslides are a major hazard in Indonesia’s volcanic terrains, where highly weathered pyroclastic rocks and intense rainfall frequently trigger slope failures. This study aims to identify geological, geomorphological, and soil physical factors controlling slope stability within the Semilir Formation of Gunungkidul, Yogyakarta. Field observations and laboratory analyses were conducted to compare outcrops affected by translational landslides with adjacent stable slopes. Key parameters include bedding orientation, soil bulk density, plasticity index, and water retention capacity. The results indicate that dip-slope bedding orientations strongly predispose slopes to translational failure, whereas counter-dip structures enhance stability. Landslide-prone slopes exhibit higher bulk density, lower plasticity, and reduced water-holding capacity, which accelerate saturation and decrease cohesion during intense rainfall. In contrast, stable slopes possess higher plasticity and greater water retention, often reinforced by vegetation roots. These findings highlight the combined role of geological structure and soil properties as reliable indicators of landslide susceptibility. The study’s novelty lies in its outcrop-scale comparative approach within a single volcanic formation, providing practical implications for slope management through vegetation reinforcement, improved drainage, and locally calibrated rainfall thresholds.
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References
- Amarasinghe, M. P., Kulathilaka, S. A. S., Robert, D. J., Zhou, A. & Jayathissa, H. A. G. (2024). Risk assessment and management of rainfall induced landslides in tropical regions: A review. Natural Hazards, 120(3). DOI: https:// doi.org/10.1007/s11069-023-06277-3.
- Arango-Carmona, M. I., Voit, P., Hürlimann, M., Aristizábal, E. & Korup, O. (2025). Hillslope torrential mountains. hazard cascades in tropical EGUsphere, 1–30. https://egusphere.copernicus.org/preprints/2025/egusphere-2025-1698/.
- Busthan, B., Pachri, H., Alimuddin, I., Bahri, S. & Bundang, S. (2024). A new approach to determining the slip surface in tuff to determine the volume of landslide material: A case study on the West Sinjai road section, Sinjai Regency, South Sulawesi, Indonesia. Journal of Degraded and Mining Lands Management, 11(2), 55335538. DOI: https://doi.org/10.15243/jdmlm.2024.112.5533.
- Chen, B., Shui, W., Liu, Y. & Deng, R. (2023). Analysis of slope stability with different vegetation types under the influence of rainfall. Forests, 14(9). DOI: https://doi.org/10.3390/f14091865.
- Cho, M. T. T., Sato, T., Saito, H., Izumi, A. & Kohgo, Y. (2024). Effects of pore water and pore air pressure on the slope failure mechanisms due to rainfall in centrifuge investigation. Geoenvironmental Disasters, 11 (1). DOI: https://doi.org/10.1186/s40677-02400305-5.
- Cynthia, C. (2024). Geomorphological Evolution of Landscapes: Processess and Timescales. Journal of Earth Science & Climatic Change. 15 (5). DOI: https://doi.org/10.4172/2157-7617.1000799.
- Demir, G., Guswa, A. J., Filipzik, J., Metzger, J. C., Römermann, C. & Hildebrandt, A. (2024). Root water uptake patterns are controlled by tree species interactions and soil water variability. Hydrology and Earth System Sciences, 28(6), 1441–1461. DOI: https://doi.org/10.5194/hess-28-1441-2024.
- Ehsan, M., Anees, M. T., Bakar, A. F. B. A. & Ahmed, A. (2025). A review of geological and triggering factors influencing landslide susceptibility: Artificial intelligence-based trends in mapping and prediction. International Journal of Environmental Science and Technology. DOI: https://doi.org/10.1007/s13762-02506741-6.
- Fata, Y. A., Hendrayanto, Erizal, Tarigan, S. D. & Katsumi, T. (2023). Modelling of mechanical roots on slope stability. Journal of Degraded and Mining Lands Management, 10(4), 47794790. DOI: https://doi.org/10.15243/jdmlm.2023.104.4779.
- He, S., Shen, Z., Neal, J., Yang, Z., Chen, J., Wang, D., Yang, Y., Zhao, P., Hu, X., Lin, Y., Rong, Y., Zheng, Y., Su, X., Kong, Y. & Hong, T. (2025). The dual-edged role of vegetation in evaluating landslide usceptibility: Evidence from watershed-scale and site-specific analyses.
- Environmental Hazards, 189, 1–38. Huang, M., Zhang, Y., Hu, J., Hei, Y., Xu, Z. & Su, J. (2023). Experimental study on pore pressure variation and erosion stability of sandy slope model under microbially induced carbonate precipitation. Sustainability, 15(16). DOI: https://doi.org/10.3390/su151612650.
- Irawan, Maswar, Yustika, R. D. & Ariani, R. (2022). Sifat fisik tanah dan metode analisisnya. Balai Penelitian Tanah. DOI: https://doi.org/10.31942/abd.v4i2.3041.
- Jia, J., Mao, C. & Tenorio, V. O. (2024). Slope stability considering multi-fissure seepage under rainfall conditions. Scientific Reports, 14(1), 1–10. DOI: https://doi.org/10.1038/s41598-024-62387-3.
- Krishna, I. P., Zangerl, C., Straka, W., Ottner, F. & Arifianti, Y. (2016). Geology, geomorphology and failure mechanism of volcanic land slide: A case study from large landslide in Banjarnegara, Indonesia. In The 3rd International Conference on Earthquake Engineering and Disaster Mitigation 2016 (ICEEDM-III 2016).
- Kumala Sari, P. T. & Wardani, M. K. (2024). The impact of cracked soil and weathering on slope stability against landslides in hilly regions with heavy rainfall. Potensi: Jurnal Sipil Politeknik, 26(2), 53–58. DOI: https://doi.org/10.35313/potensi.v26i2.6359.
- LaHusen, S. R. & Grant, A. R. R. (2024). Complex landslide patterns explained by local intraunit variability of stratigraphy and structure: Case study in the Tyee Formation, Oregon, USA. Engineering Geology, 329, 107387. DOI: https://doi.org/10.1016/j.enggeo.2023.107387
- Leonarduzzi, E., McArdell, B. W. & Molnar, P. (2021). Rainfall-induced shallow landslides and soil wetness: Comparison of physically based probabilistic predictions. Hydrology and Earth System Sciences, 25 (11), 5937–5950. DOI: https://doi.org/105194/hess-25-5937-2021.
- Lira, B. S., dos Santos Junior, O. F., de Freitas Neto, O. & Sousa, M. N. de M. (2024). Evaluation of the effects of rainwater infiltration on slope instability mechanisms. Sustainability, 16 (21). DOI: https://doi.org/10.3390/su16219530.
- Lovita, V. & Sulistyo, B. (2025). Conservation strategy based on soil erodibility with several land covers and slopes in the upstream of Air Bengkulu Watershed. Jurnal Lahan Suboptimal, 14(1), 51–61. DOI: https://doi.org/10.36706/JLSO.14.1.2025.731.
- Marzini, L., D’Addario, E., Papasidero, M. P., Chianucci, F. & Disperati, L. (2023). Influence of root reinforcement on shallow landslide distribution: A case study in Garfagnana (Northern Tuscany, Italy). Geosciences, 13 (11). DOI: https://doi.org/10.3390/geosciences13110326.
- Masi, E. B., Segoni, S. & Tofani, V. (2021). Root reinforcement in slope stability models: A review. Geosciences, 11(5). DOI: https://doi.org/10.3390/geosciences11050212.
- Millán-Arancibia, C. & Lavado-Casimiro, W. (2023). Rainfall thresholds estimation for shallow landslides in Peru from gridded daily data. Natural Hazards and Earth System Sciences, 23(3), 1191–1206. DOI: https://doi.org/10.5194/nhess-23-1191-2023.
- Muntohar, A. S., Ikhsan, J., Liao, H. J., Jotisankasa, A. & Jetten, V. G. (2022). Rainfall infiltration-induced slope instability of the unsaturated volcanic residual soils during wet seasons in Indonesia. Indonesian Journal on Geoscience, 9(1), 71–85. DOI: https://doi.org/10.17014/ijog.9.1.71-85.
- Pelascini, L., Steer, P., Mouyen, M. & Longuevergne, L. (2022). Finite-hillslope analysis of landslides triggered by excess pore water pressure: The roles of atmospheric pressure and rainfall infiltration during typhoons. Natural Hazards and Earth System Sciences, 22(10), 3125–3141. DOI: https://doi.org/10.5194/nhess-22-3125-2022.
- Peng, B., & Wu, X. (2024). Optimizing rainfall triggered landslide thresholds for daily landslide hazard warning in the Three Gorges Reservoir area. Natural Hazards and Earth System Sciences, 24(11), 3991–4013. DOI: https://doi.org/10.5194/nhess-24-3991-2024.
- Pisano, M. & Cardile, G. (2023). Probabilistic analyses of root-reinforced slopes using Monte Carlo simulation. Geosciences, 13(3). DOI:https://doi.org/10.3390/geosciences13030075.
- Salee, R., Chinkulkijniwat, A., Yubonchit, S., Horpibulsuk, S., Wangfaoklang, C. & Soisompong, S. (2022). New threshold for landslide warning in the southern part of Thailand integrates cumulative rainfall with event rainfall depth-duration.Natural Hazards,113(1),125– 141. DOI: https://doi.org/10.1007/s11069-022-05292-0.
- Sari, P. T. K., Mochtar, I. B. & Chaiyaput, S. (2023). Effectiveness of horizontal sub-drain for slope stability on cracked soil using numerical model. Geotechnical and Geological Engineering, 41(8), 4821–4844. DOI: https://doi.org/10.1007/s10706-023-02550-1.
- Soil Survey Division Staff. (2017). Soil survey manual (U.S. Department of Agriculture Handbook 18). DOI: https://doi.org/10.2307/1233734.
- Song, H., Huang, J., Zhang, Z., Jiang, Q., Liu, L., He, C. & Zhou, Y. (2024). Analysis of water migration and spoil slope stability under the coupled effects of rainfall and root reinforcement based on the unsaturated soil theory. Forests, 15(4). DOI: https://doi.org/10.3390/f15040640 .
- Spiekermann, R. I., McColl, S., Fuller, I., Dymond, J., Burkitt, L. & Smith, H. G. (2021). Quantifying the influence of individual trees on slope stability at landscape scale. Journal of Environmental Management, 286. DOI: https://doi.org/10.1016/j. jenvman.2021.112194.
- Surono. (2009). Litostratigrafi Pegunungan Selatan Bagian Timur Daerah Istimewa Yogyakarta dan Jawa Tengah. Jurnal Geologi dan Sumberdaya Mineral, 19(3), 209–221.
- Tang, L., Yan, Y., Zhang, F., Li, X., Liang, Y., Yan, Y., Zhang, H. & Zhang, X. (2024). A case study for analysis of stability and treatment measures of a landslide under rainfall with the changes in pore water pressure. Water, 16(21). DOI: https://doi.org/10.3390/w16213113.
- Wu, J., Yang, G., Ma, Y., Guo, X., Lu, N., Chen, Z., Wang, Z., Wang, N. & Du, H. (2024). Effects of vegetation restoration on soil aggregate characteristics and soil erodibility at gully head in Loess hilly and gully region. Scientific Reports, 14(1). DOI: https://doi.org/10.1038/s41598024-82469-6.
- Xin, C., Li, W., Wang, Z., Feng, W., Hajirasouliha, I. & Yu, X. (2024). Shaking table tests on the stability of dip and anti-dip rock slopes with structural planes induced by seismic motions. Engineering Geology, 341, 107707. DOI: https://doi.org/10.1016/j.enggeo.2024.107707.
- Zhang, X., Wang, H., Gao, Z., Xiang, K., Zhai, Q., Satyanaga, A. & Chua, Y. S. (2023). Evaluation of the performance of the horizontal drain in drainage of the infiltrated water from slope soil under rainfall conditions. Sustainability, 15(19). DOI: https://doi.org/10.3390/su151914163.
- Zhou, S. H., Zhou, S. K., Zhang, J. C. & Tan, X. (2021). Effect of bedding orientation and spatial variability of stratification shear strength on stability of transversely isotropic rock slope.Frontiers in Physics, 9, 1–7. DOI: https://doi.org/10.3389/fphy.2021.777216.
- Zhuang, J., Peng, J., Du, C., Zhu, Y. & Kong, J. (2024). Shallow-landslide stability evaluation in loess areas according to the revised infinite slope model: A case study of the 7.25 Tianshui sliding-flow landslide events of 2013 in the southwest of the Loess Plateau, China. Natural Hazards and Earth System Sciences, 24(7), 2615–2631. DOI: https://doi.org/10.5194/nhess-24-2615-2024.
References
Amarasinghe, M. P., Kulathilaka, S. A. S., Robert, D. J., Zhou, A. & Jayathissa, H. A. G. (2024). Risk assessment and management of rainfall induced landslides in tropical regions: A review. Natural Hazards, 120(3). DOI: https:// doi.org/10.1007/s11069-023-06277-3.
Arango-Carmona, M. I., Voit, P., Hürlimann, M., Aristizábal, E. & Korup, O. (2025). Hillslope torrential mountains. hazard cascades in tropical EGUsphere, 1–30. https://egusphere.copernicus.org/preprints/2025/egusphere-2025-1698/.
Busthan, B., Pachri, H., Alimuddin, I., Bahri, S. & Bundang, S. (2024). A new approach to determining the slip surface in tuff to determine the volume of landslide material: A case study on the West Sinjai road section, Sinjai Regency, South Sulawesi, Indonesia. Journal of Degraded and Mining Lands Management, 11(2), 55335538. DOI: https://doi.org/10.15243/jdmlm.2024.112.5533.
Chen, B., Shui, W., Liu, Y. & Deng, R. (2023). Analysis of slope stability with different vegetation types under the influence of rainfall. Forests, 14(9). DOI: https://doi.org/10.3390/f14091865.
Cho, M. T. T., Sato, T., Saito, H., Izumi, A. & Kohgo, Y. (2024). Effects of pore water and pore air pressure on the slope failure mechanisms due to rainfall in centrifuge investigation. Geoenvironmental Disasters, 11 (1). DOI: https://doi.org/10.1186/s40677-02400305-5.
Cynthia, C. (2024). Geomorphological Evolution of Landscapes: Processess and Timescales. Journal of Earth Science & Climatic Change. 15 (5). DOI: https://doi.org/10.4172/2157-7617.1000799.
Demir, G., Guswa, A. J., Filipzik, J., Metzger, J. C., Römermann, C. & Hildebrandt, A. (2024). Root water uptake patterns are controlled by tree species interactions and soil water variability. Hydrology and Earth System Sciences, 28(6), 1441–1461. DOI: https://doi.org/10.5194/hess-28-1441-2024.
Ehsan, M., Anees, M. T., Bakar, A. F. B. A. & Ahmed, A. (2025). A review of geological and triggering factors influencing landslide susceptibility: Artificial intelligence-based trends in mapping and prediction. International Journal of Environmental Science and Technology. DOI: https://doi.org/10.1007/s13762-02506741-6.
Fata, Y. A., Hendrayanto, Erizal, Tarigan, S. D. & Katsumi, T. (2023). Modelling of mechanical roots on slope stability. Journal of Degraded and Mining Lands Management, 10(4), 47794790. DOI: https://doi.org/10.15243/jdmlm.2023.104.4779.
He, S., Shen, Z., Neal, J., Yang, Z., Chen, J., Wang, D., Yang, Y., Zhao, P., Hu, X., Lin, Y., Rong, Y., Zheng, Y., Su, X., Kong, Y. & Hong, T. (2025). The dual-edged role of vegetation in evaluating landslide usceptibility: Evidence from watershed-scale and site-specific analyses.
Environmental Hazards, 189, 1–38. Huang, M., Zhang, Y., Hu, J., Hei, Y., Xu, Z. & Su, J. (2023). Experimental study on pore pressure variation and erosion stability of sandy slope model under microbially induced carbonate precipitation. Sustainability, 15(16). DOI: https://doi.org/10.3390/su151612650.
Irawan, Maswar, Yustika, R. D. & Ariani, R. (2022). Sifat fisik tanah dan metode analisisnya. Balai Penelitian Tanah. DOI: https://doi.org/10.31942/abd.v4i2.3041.
Jia, J., Mao, C. & Tenorio, V. O. (2024). Slope stability considering multi-fissure seepage under rainfall conditions. Scientific Reports, 14(1), 1–10. DOI: https://doi.org/10.1038/s41598-024-62387-3.
Krishna, I. P., Zangerl, C., Straka, W., Ottner, F. & Arifianti, Y. (2016). Geology, geomorphology and failure mechanism of volcanic land slide: A case study from large landslide in Banjarnegara, Indonesia. In The 3rd International Conference on Earthquake Engineering and Disaster Mitigation 2016 (ICEEDM-III 2016).
Kumala Sari, P. T. & Wardani, M. K. (2024). The impact of cracked soil and weathering on slope stability against landslides in hilly regions with heavy rainfall. Potensi: Jurnal Sipil Politeknik, 26(2), 53–58. DOI: https://doi.org/10.35313/potensi.v26i2.6359.
LaHusen, S. R. & Grant, A. R. R. (2024). Complex landslide patterns explained by local intraunit variability of stratigraphy and structure: Case study in the Tyee Formation, Oregon, USA. Engineering Geology, 329, 107387. DOI: https://doi.org/10.1016/j.enggeo.2023.107387
Leonarduzzi, E., McArdell, B. W. & Molnar, P. (2021). Rainfall-induced shallow landslides and soil wetness: Comparison of physically based probabilistic predictions. Hydrology and Earth System Sciences, 25 (11), 5937–5950. DOI: https://doi.org/105194/hess-25-5937-2021.
Lira, B. S., dos Santos Junior, O. F., de Freitas Neto, O. & Sousa, M. N. de M. (2024). Evaluation of the effects of rainwater infiltration on slope instability mechanisms. Sustainability, 16 (21). DOI: https://doi.org/10.3390/su16219530.
Lovita, V. & Sulistyo, B. (2025). Conservation strategy based on soil erodibility with several land covers and slopes in the upstream of Air Bengkulu Watershed. Jurnal Lahan Suboptimal, 14(1), 51–61. DOI: https://doi.org/10.36706/JLSO.14.1.2025.731.
Marzini, L., D’Addario, E., Papasidero, M. P., Chianucci, F. & Disperati, L. (2023). Influence of root reinforcement on shallow landslide distribution: A case study in Garfagnana (Northern Tuscany, Italy). Geosciences, 13 (11). DOI: https://doi.org/10.3390/geosciences13110326.
Masi, E. B., Segoni, S. & Tofani, V. (2021). Root reinforcement in slope stability models: A review. Geosciences, 11(5). DOI: https://doi.org/10.3390/geosciences11050212.
Millán-Arancibia, C. & Lavado-Casimiro, W. (2023). Rainfall thresholds estimation for shallow landslides in Peru from gridded daily data. Natural Hazards and Earth System Sciences, 23(3), 1191–1206. DOI: https://doi.org/10.5194/nhess-23-1191-2023.
Muntohar, A. S., Ikhsan, J., Liao, H. J., Jotisankasa, A. & Jetten, V. G. (2022). Rainfall infiltration-induced slope instability of the unsaturated volcanic residual soils during wet seasons in Indonesia. Indonesian Journal on Geoscience, 9(1), 71–85. DOI: https://doi.org/10.17014/ijog.9.1.71-85.
Pelascini, L., Steer, P., Mouyen, M. & Longuevergne, L. (2022). Finite-hillslope analysis of landslides triggered by excess pore water pressure: The roles of atmospheric pressure and rainfall infiltration during typhoons. Natural Hazards and Earth System Sciences, 22(10), 3125–3141. DOI: https://doi.org/10.5194/nhess-22-3125-2022.
Peng, B., & Wu, X. (2024). Optimizing rainfall triggered landslide thresholds for daily landslide hazard warning in the Three Gorges Reservoir area. Natural Hazards and Earth System Sciences, 24(11), 3991–4013. DOI: https://doi.org/10.5194/nhess-24-3991-2024.
Pisano, M. & Cardile, G. (2023). Probabilistic analyses of root-reinforced slopes using Monte Carlo simulation. Geosciences, 13(3). DOI:https://doi.org/10.3390/geosciences13030075.
Salee, R., Chinkulkijniwat, A., Yubonchit, S., Horpibulsuk, S., Wangfaoklang, C. & Soisompong, S. (2022). New threshold for landslide warning in the southern part of Thailand integrates cumulative rainfall with event rainfall depth-duration.Natural Hazards,113(1),125– 141. DOI: https://doi.org/10.1007/s11069-022-05292-0.
Sari, P. T. K., Mochtar, I. B. & Chaiyaput, S. (2023). Effectiveness of horizontal sub-drain for slope stability on cracked soil using numerical model. Geotechnical and Geological Engineering, 41(8), 4821–4844. DOI: https://doi.org/10.1007/s10706-023-02550-1.
Soil Survey Division Staff. (2017). Soil survey manual (U.S. Department of Agriculture Handbook 18). DOI: https://doi.org/10.2307/1233734.
Song, H., Huang, J., Zhang, Z., Jiang, Q., Liu, L., He, C. & Zhou, Y. (2024). Analysis of water migration and spoil slope stability under the coupled effects of rainfall and root reinforcement based on the unsaturated soil theory. Forests, 15(4). DOI: https://doi.org/10.3390/f15040640 .
Spiekermann, R. I., McColl, S., Fuller, I., Dymond, J., Burkitt, L. & Smith, H. G. (2021). Quantifying the influence of individual trees on slope stability at landscape scale. Journal of Environmental Management, 286. DOI: https://doi.org/10.1016/j. jenvman.2021.112194.
Surono. (2009). Litostratigrafi Pegunungan Selatan Bagian Timur Daerah Istimewa Yogyakarta dan Jawa Tengah. Jurnal Geologi dan Sumberdaya Mineral, 19(3), 209–221.
Tang, L., Yan, Y., Zhang, F., Li, X., Liang, Y., Yan, Y., Zhang, H. & Zhang, X. (2024). A case study for analysis of stability and treatment measures of a landslide under rainfall with the changes in pore water pressure. Water, 16(21). DOI: https://doi.org/10.3390/w16213113.
Wu, J., Yang, G., Ma, Y., Guo, X., Lu, N., Chen, Z., Wang, Z., Wang, N. & Du, H. (2024). Effects of vegetation restoration on soil aggregate characteristics and soil erodibility at gully head in Loess hilly and gully region. Scientific Reports, 14(1). DOI: https://doi.org/10.1038/s41598024-82469-6.
Xin, C., Li, W., Wang, Z., Feng, W., Hajirasouliha, I. & Yu, X. (2024). Shaking table tests on the stability of dip and anti-dip rock slopes with structural planes induced by seismic motions. Engineering Geology, 341, 107707. DOI: https://doi.org/10.1016/j.enggeo.2024.107707.
Zhang, X., Wang, H., Gao, Z., Xiang, K., Zhai, Q., Satyanaga, A. & Chua, Y. S. (2023). Evaluation of the performance of the horizontal drain in drainage of the infiltrated water from slope soil under rainfall conditions. Sustainability, 15(19). DOI: https://doi.org/10.3390/su151914163.
Zhou, S. H., Zhou, S. K., Zhang, J. C. & Tan, X. (2021). Effect of bedding orientation and spatial variability of stratification shear strength on stability of transversely isotropic rock slope.Frontiers in Physics, 9, 1–7. DOI: https://doi.org/10.3389/fphy.2021.777216.
Zhuang, J., Peng, J., Du, C., Zhu, Y. & Kong, J. (2024). Shallow-landslide stability evaluation in loess areas according to the revised infinite slope model: A case study of the 7.25 Tianshui sliding-flow landslide events of 2013 in the southwest of the Loess Plateau, China. Natural Hazards and Earth System Sciences, 24(7), 2615–2631. DOI: https://doi.org/10.5194/nhess-24-2615-2024.