--> Study of Relative Active Tectonic Features on Kaladan- Mrauk U Fault, Rakhine Coastal Region

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Study of Relative Active Tectonic Features on Kaladan- Mrauk U Fault, Rakhine Coastal Region


This study focused the regional assessment of active tectonics based on geomorphic indices in morphology and topography. The present area lie along the western base of the Indo-Myanmar ranges in the Rakhine Coastal region, existing in the India-West Burma collision zone within the accretionary wedge region. It is located along the Mrauk U Fault that is also known as Kaladan -Mrauk U Fault. The study covers the area between Latitude N20˚ and N22˚ and between Longitude E92˚ –E94˚. In the area, most of Miocene sedimentary rocks show ENE dipping with high angle (~50˚-65˚) and generally eastern part of the area show highly folded nature. From the stress field analysis, the compressional field show in NE-SW regime and the dilational field show in NNW-SSE regime. Thus the study could have identified two different senses of shear along a fault trace. In the longitudinal cross-section along the Andaman subduction zone at Lat N20˚-N21˚, the slab appears continuous (Jeremy Dale Persicek, 2009) based on the neotectonic features and previous earthquake data (from 2000 to 2017 November) around the study area (the focal depth 30km-70km, effected magnitude is 4M -6M and 390 times) . From the focal depth model analysis and earthquake data indicated that Mrauk U fault is an active fault. Possible kinematic result is: the overthrust faults on the Burma Plate (slab above the subduction) caused upward slip motion along the fault plane because the subduction slab has been active beneath the study area. Also, fault dip style and shear nature indicate oblique slip shear or dextral reverse sense of shear. On the other hand, although the Kaladan – Mrauk U fault system expresses dextral features (with oblique slip), it has been active in and active thrust manner. For methodology of this study, we analyzed on three selected area along the Kaladan-Mrauk U fault. The data on geomorphic indices that have been used in following indices: index of mountain front sinuosity (Smf) ratio of valley floor width to valley height (Vf) index of drainage basin shape (Bs) and finally expressed as an index of relative active tectonics (Iat). That provided into information of potential tectonic activity. According to kinematic result of Iat (S/n>2), the study area is fall in the moderately active tectonics region.