Spatial landscape response to active tectonics along the Western Mae Chan Fault, Northern Thailand

Mae Chan Fault (MCF) is one of the active faults in northern Thailand, Lao PDR, and Myanmar. Despite fault activeness, the records of recent earthquakes show a lower frequency and magnitude of earthquakes across the MCF than those of the surrounding regions. The morphotectonic analysis evaluates relative tectonic activity based on the drainage systems’ adjustment and geomorphic expressions. We analyzed the Western Mae Chan Fault (WMCF) to explore the spatial response of landscape to relative rock uplift and long-term deformation. We delineated fault segment lines from the remote sensing and the topographic expressions from the digital elevation model. We analyzed the topographic variations from 70 low-order channels developed along the WMCF and evaluated the tectonic activity using geomorphic indices, including the hypsometric integral and hypsometric curve, the standardized stream length-gradient index, the elongation ratio, the drainage basin asymmetrical factor, the mountain front sinuosity, and the valley floor width-to-height ratio. Combining these geomorphic factors with field observations provides the relative indices of active tectonics (RIAT). Our findings revealed that lineament detection from the remote sensing technique indicated the ENE-WSW direction of fault segments. The overall tectonic activity is relatively moderate, but high tectonic activity is present along the western terrain and high topography in the east. The various tectonic activities are consistent with the spatial variations in lineament density and differential rock uplift, where the terrain experienced spatial variations in transtensional and transpressional regimes. This study highlights the potential long-term tectonic activity along the WMCF that dominantly sculpts the modern landscape.