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The active tectonic aspects of the Indo-Myanmar Range (IMR) have not yet been studied in detail in spite of the fact that it's seismically active. In the present study qualitative and quantitative geomorphic analyses have been carried out to understand the active tectonic evolution of Nungba, and Barak- Makru thrust sheets (NBTS and BMTS) in the central part of IMR. The focus of the study is on understanding the active spatial growth pattern of adjacent thrust sheets in an evolving mountain range and providing baseline data for further detailed seismotectonic and seismic hazard vulnerability analyses. Drainage characteristics, disposition of landforms and statistical analyses of Normalized Steepness Index (ksn), Hypsometric Integral (HI) and Transverse Topography Symmetry Factor (T), computed for a total of 164 4th-order drainage basins, reveal that both of these adjoining thrust sheets are actively uplifting. Higher values of ksn (mode = 111) and HI (mode = 0.46) in NBTS suggest its faster uplift than the BMTS, which has comparatively lower values of ksn (mode = 56) and HI (mode = 0.43). Moreover, the northern parts of the both the thrust sheets are uplifting faster than their southern parts due to along-strike variations in the movement on their basal thrusts, as a result of which the NBTS has been south-southeastwardly down-tilting and the BMTS is south-southwestwardly down-tilting. The study reveals that both the adjacently lying NBTS and BMTS have almost the same spatial growth patterns that are mainly controlled by the movements on their basal thrusts. [ABSTRACT FROM AUTHOR]

Southwestern Taiwan exhibits multiple fold-thrust systems as a consequence of the interaction between the Philippine Sea Plate and the Eurasian Plate. A prominent geological feature of this region is the extensive layer of GuTingKeng mudstone, with a thickness of approximately 4 km, which serves as a source material for the formation of mud or shale diapirs. The 2016 Mw 6.4 Meinong earthquake, striking southwestern Taiwan at a depth of 15–20 km and inducing approximately 100 mm of uplift, has prompted investigations into the potential involvement of shallow structures (< 4 km) in this uplift. Recent studies have proposed that such shallow structures may have contributed significantly to the observed uplift during the earthquake. This study aims to elucidate the role of buried mud diapirs in the context of coseismic deformation. Here, we present a modeling approach that utilizes sill-like dislocations to simulate the deformation at the upper tip of the diapir. Our results indicate a vertical opening of approximately 60 mm at a depth of 1.4 km, which closely aligns with the spatial distribution of tomographic and gravity anomalies. We also examine how the coseismic stress changes induced by the Meinong earthquake can lead to a dilatational strain of about 1.2 microstrain within the shallow depth range of 0–4 km, resulting in extension within our modeled region. In contrast, the dilatational strain diminishes from 0.2 to − 1.2 microstrain at greater depths (4–8 km), implying compression in the subsurface beneath the diapir's top. This study discusses the potential mechanisms how fluid-rich and high-pressure mudstone may be deformed through coseismic process and how mud diapirs may contribute to additional deformation within the seismic cycle. [ABSTRACT FROM AUTHOR]