Sains Malaysiana 50(7)(2021): 1871-1884

http://doi.org/10.17576/jsm-2021-5007-04

Geophysical Characterization of a Sinkhole Region: A Study Toward Understanding Geohazards in the Karst Geosites

(Pencirian Geofizik di Kawasan Lohong: Suatu Kajian untuk Memahami Bahaya Geologi dalam Geotapak Karst)

SAWASDEE YORDKAYHUN*

Division of Physical Science, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla, 90112, Thailand

Geophysics Research Center, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla, 90112, Thailand

Received: 16 March 2020/Accepted: 19 November 2020

ABSTRACT

The outstanding geosites in Satun UNESCO Global Geopark, Thailand are mainly karst topography. Sinkhole which is originated from the dissolution of karst rocks by groundwater or acidic rainwater is one of the potential natural disasters in these geosites. To gain the confident among geotourism, detecting karst features, cavities and surficial dissolution is crucial in risk assessment and sustainable geopark management. As a part of geohazard assessment, non-invasive geophysical methods were applied for detecting near-surface defects and karst features. In this study, electrical resistivity tomography (ERT), seismic tomography and multichannel analysis of surface waves (MASW) have been integrated to understand the mechanism of an existing sinkhole formation in Satun Geopark region. ERT appeared to be an effective approach to investigate the cavity development at shallow subsurface. MASW and seismic tomography were combined to help constrain the interpretation of lithology and karst features in vicinity of the sinkhole. The results indicated that the sinkhole occurrence in this area was probably developed by forming of cavity due to an increased dissolution of the fractured limestone bedrock. This carbonate layer is in contact with the overlying groundwater and weathering shale or cohesive soil layer. The changing of water table and infiltration of surface water by heavy rainfall allowed for a sudden vertical downward of overlying sediments into the empty voids, leading to the sinkhole hazard.

Keywords: Geosite; resistivity; Satun Geopark; seismic; sinkhole

ABSTRAK

Geotapak yang luar biasa di Satun UNESCO Global Geopark, Thailand adalah topografi karst. Kawasan lohong yang berasal daripada pembubaran batu karst oleh air bawah tanah atau air hujan berasid adalah salah satu potensi bencana alam di geotapak ini. Untuk mendapatkan keyakinan di kalangan pelancongan geografi, mengesan ciri karst, rongga dan pembubaran permukaan sangat penting dalam penilaian risiko dan kelestarian pengurusan taman geologi. Sebagai sebahagian daripada penilaian bahaya geologi, kaedah geofizik tidak invasif digunakan untuk mengesan kecacatan permukaan dekat dan ciri karst. Dalam kajian ini, tomografi kerintangan elektrik (ERT), tomografi seismik dan analisis pelbagai saluran ombak permukaan (MASW) telah disatukan untuk memahami mekanisme pembentukan kawasan lohong yang ada di wilayah taman geologi Saturn. Kelihatan ERT merupakan pendekatan yang berkesan untuk mengkaji perkembangan rongga di permukaan bawah yang cetek. MASW dan tomografi seismos digabungkan untuk membantu mengekang tafsiran litologi dan ciri karst di sekitar kawasan lohong. Hasil kajian menunjukkan bahawa kejadian lubang di kawasan ini mungkin dikembangkan dengan pembentukan rongga akibat peningkatan pelarutan batuan dasar batu kapur yang patah. Lapisan karbonat ini bersentuhan dengan air bawah tanah dan lapisan serpihan cuaca atau lapisan tanah yang bersatu. Perubahan meja air dan penyusupan air permukaan oleh hujan lebat memungkinkan mendapan mendadak ke bawah ruang kosong, yang membawa kepada bahaya kawasan lohong.

Kata kunci: Geotapak kawasan lohong; kerintangan; seismos; taman geologi Saturn

REFERENCES

Abidin, M.H.Z., Saad, R., Wijeyessekera, D.C., Ahmad, F., Baharuddin, M.F.T., Tajudin, S.A.A. & Madun, A. 2017. The influences of basic physical properties of clayey silt and silty sand on its laboratory electrical resistivity value in loose and dense conditions. Sains Malaysiana 46(10): 1959-1969.

Beres, M., Luetscher, M. & Olivier, R. 2001. Integration of ground-penetrating radar and microgravimetric methods to map shallow caves. Journal of Applied Geophysics 46(4): 249-262.

Bunopas, S. 1981. Paleogeographic history of Western Thailand and adjacent parts of Southeast Asia - A plate tectonics interpretation. Ph.D. thesis. New Zealand:  Victoria University of Wellington. Reprinted in 1982 as Geological Survey Paper No.5. Thailand: Geological Survey Division, Department of Mineral Resources.

Carrière, S.D., Chalikakis, K., Sénéchal, G., Danquigny, C. & Emblanch, C. 2013. Combining electrical resistivity tomography and ground penetrating radar to study geological structuring of karst unsaturated zone. Journal of Applied Geophysics 94: 31-41.

Debeglia, N., Bitri, A. & Thierry, P. 2006. Karst investigations using microgravity and MASW; application to Orleans, France. Journal of Near Surface Geophysics 4(4): 215-225.

Department of Mineral Resources. 2013. Geological Zoning for Geological Resources Management in Satun Province. Bangkok: Department of Mineral Resources. p. 123.

Department of Mineral Resources. 1997. Sinkhole Detection and Mitigation in Satun Province. Songkhla: Mineral Resources Office. p. 57.

Dobecki, T.L. & Upchurch, S.B. 2006. Geophysical applications to detect sinkholes and ground subsidence. The Leading Edge 25(3): 336-341.

Ezersky, M. 2008. Geoelectric structure of the EinGedi sinkhole occurrence site at the Dead Sea shore in Israel. Journal of Applied Geophysics 64(3-4): 56-69.

Hagedoorn, J.G. 1959. The plus-minus method of interpreting seismic refraction sections. Geophysical Prospecting 7(2): 158-182.

Helly, M.A.A., Muhammad, R.F., Shuib, M.K., Fatt, N.T., Abdullah, W.H., Bakar, A.A. & Kugler, R. 2019. Rock slope stability analysis based on terrestrial LiDAR on karst hills in Kinta Valley Geopark, Perak, Peninsular Malaysia. Sains Malaysiana 48(11): 2595-2604.

Kruse, S., Grasmueck, M., Weiss, M. & Viggiano, D. 2006. Sinkhole structure imaging in covered karst terrain. Geophysical Research Letters 33(16): L16405.

Lai, G.H., Mang, W.J., Rafek, A.G., Serasa, A.S., Mazlan, N.A., Razib, A.M.M., Hussin, A., Ern, L.K. & Mohamed, T.R. 2018. Stability assessment of limestone cave: Batu Caves, Selangor, Malaysia. Sains Malaysiana 47(1): 59-66.

Loke, M.H. 2003. Rapid 2D Resistivity & IP Inversion using the Least-Squares Method. Geotomo Software. https://www.academia.edu/39226833/Rapid_2_D_Resistivity_and_IP_inversion_using_the_least_squares_method.

Martínez-Moreno, F.J., Galindo-Zaldívar, J., Pedrera, A., Teixido, T., Ruanoa, T., Peña, J.A., González-Castillo, L. Ruiz-Constán, A., López-Chicano, M. & Martín-Rosales, M. 2014. Integrated geophysical methods for studying the karst system of Gruta delas Maravillas (Aracena, Southwest Spain). Journal of Applied Geophysics 107: 149-162.

Olona, J., Pulgar, J.A., Viejo, G.F., Fernandez, C.L. & Cortina, J.M. 2010. Weathering variations in a granite massif and relted geotechnical properties through seismic and electrical resistivity methods. Near Surface Geophysics 8: 585-599.

Ortiz, D.G. & Crespo, T.M. 2012. Assessing the risk of subsidence of a sinkhole collapse using ground penetrating radar and electrical resistivity tomography. Engineering Geology 149(2): 1-12.

Palmer, D. 1980. The Generalized Reciprocal Method of Seismic Refraction Interpretation. Australia: Society of Exploration Geophysics. p. 104.

Park, C.B., Miller, R.D. & Xia, J. 1999. Multichannel analysis of surface waves MASW. Geophysics 64(3): 800-808.

Ruban, D.A. 2018. Karst as important resource for geopark-based tourism: Current state and biases. Resources 7(4): 82.

Sardsud, A. & Wongwanich, T. 2017. Role of geoheritage sites in contribution to development of Satun aspiring geopark. DMR-CCOP-TNCU Technical Seminar on Biostratigraphy and Karst Morphology of Satun Aspiring Geopark. pp. 50-59.

Satarugsa, P. 2011. The lessons learnt from geophysical investigation of sinkholes in rock salt in Thailand. International Conference on Geology, Geotechnology and Mineral Resources of Indochina (GEOINDO 2011). pp. 445-455.

Signanini, P. & Torrese, P. 2004. Application of high resolution shear-wave seismic methods to a geotechnical problem. Bulletin of Engineering Geology and the Environment 63: 329-336.

Thepju, W., Yamansabedean, N. & Bamrungsong, P. 2017. Karst features in Satun geopark, Satun province. DMR-CCOP-TNCU Technical Seminar on Biostratigraphy and Karst Morphology of Satun Aspiring Geopark. Thailand: Satun Aspiring Geopark. pp. 50-59.

UNESCO. 2020. Global Geoparks. http://www.unesco.org/new/en/natural-sciences/environment/earth-sciences/unesco-global-geoparks/. Accessed on 11 March 2020.

Van Shoor, M. 2002. Detection of sinkholes using 2D electrical resistivity imaging. Journal of Applied Geophysics 50(4): 393-399.

Waltham, T., Bell, T. & Culshaw, M. 2005. Sinkholes and Subsidence. Berlin: Springer.

Wongwanich, T. 1990. Lithostratigraphy, sedimentology and digenesis of the Ordovician carbonates, Southern Thailand. University of Tasmania. Ph.D. Thesis. p. 215.

Xia, J., Miller, R.D. & Park, C.B. 1999. Estimation of near-surface shear wave velocity by inversion of Rayleigh waves. Geophysics 64(3): 691-700.

Yordkayhun, S., Tryggvason, A., Norden, B., Juhlin, C. & Bergman, B. 2009. 3D seismic traveltime tomography imaging of the shallow subsurface at the CO2SINK project site, Ketzin, Germany. Geophysics 74: G1-G15.

Zhou, W., Beck, B.F. & Adams, A.L. 2002. Effective electrode array in mapping karst hazards in electrical resistivity tomography. Journal of Environmental Geology 42: 922-928.

*Corresponding author; email: sawasdee.y@psu.ac.th