Abstract—Phayao Fault Zone (PFZ) is one of the active fault zones in Northern Thailand that has triggered low-magnitude earthquakes in Lampang, Phayao, and vicinities. Despite an active fault zone, the amount of deformation on the landscape affected by tectonic processes is largely unknown. In the study, we used morphotectonic analysis from geomorphic indices to evaluate tectonic activity across Khuang Kom and Ban Kho faults, the two main active faults along the west of the PEZ. These faults are bounded by high terrains in the west and by Mueang Pan sub-basin in the east. A high-resolution digital elevation model was used to extract topographic and hydrologic characteristics across the study site. We primarily analyzed two geomorphic indices of mountain front sinuosity (Smf) and stream length-gradient (SL). The combination of these indices potentially indicates the degree of fault activities and the implication of deformation and tectonic processes. The morphotectonic analysis revealed that the lineament patterns of Khuang Kom and Ban Kho faults mainly trend in the N-S direction. Most drainage patterns are parallel and rectangular drainage patterns, indicating numerous joints and minor faults. Analysis of geomorphic indices from these faults shows that the value of Smf varies from 1.02-2.04, and 89% of the study site is considered an active mountainous area. The value of SL mostly ranges from moderate to high gradient meters near the base of the mountain. Our finding suggests that the location of two abutting faults experiences the highest level of rock uplift and/or deformation from oblique-slip fault movement due to the effects of lithologic contact and intersecting fault networks. Our study optimally provides an insight into the advantage of using topographic analysis and geomorphic indices as a tool to estimate tectonic activity and evaluate the potential deformation in the region.
 

Keywords—phayao fault zone, khuang kom fault, ban kho fault, morphotectonic analysis, geomorphic indices, tectonics

Cite: Pichawut Manopkawee and Jiratchaya Khamkaew, "Assessment of Morphotectonics along Western Phayao Fault Zone in Northern Thailand," International Journal of Geology and Earth Sciences, Vol. 9, No. 1, pp. 11-15, June 2023. doi: 10.18178/ijges.9.1.11-15

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