Continued structural descent of the Indian lithosphere below the Sunda-Andaman trench produced several destructive large to great earthquakes in the region of Andaman and Nicobar Islands. The pattern of strain accumulation and its release in the context of great plate boundary mega thrust earthquakes and slip partitioning along active faults in the Andaman and Nicobar region during these events is unclear, owing to lack of on-fault primary paleoseismic evidences, structural complexity associated with subduction processes and lack of primary surface ruptures of large to huge magnitude earthquakes. In this context, preliminary paleoseismic trench investigations were performed across a 6-m high fault scarp at Bathubasti (South Andaman) to understand the slip partitioning and rupture dynamics of subduction zone earthquakes. Ground-penetrating radar (GPR) profiles and the trench exposure across the scarp suggest progressive deformation and several episodes of co-seismic scarp generation where Andaman Flysch Sandstone (Oligocene) is in fault contact with the late Holocene sediments. A total of eight stratigraphic units (a to g) including three fault strands (F0, F1, and F2) were observed and mapped in the trench stratigraphy. OSL ages constrain that event 1 occurred along F0 around 2312 ± 302 years BP and thrust unit (g) Andaman Flysch -bedrock over unit (f) paleosols. Event 2 has deformed unit (C)-medium sand bed and the basal portion of unit (b)-fine sand bed along F1 and F2 around 422 ± 57 years BP. Given the scarp height of 6 m and with, a vertical displacement of approximately 3 m of unit (g)- bed rock along low-angle fault (θ = 18°) implies an average slip rate of 4.12 mm/year, shortening rate of 3.88 mm/year, and an uplift rate of 4.54 mm/year.

Sun达-安达曼海沟下方印度岩石圈持续的结构下降，在安达曼和尼科巴群岛地区造成了几次破坏性的大到大地震。在这些事件期间，板块边界特大逆冲地震和沿活动断层沿安达曼和尼科巴地区的活动断层滑动分布的情况下，应变积累及其释放的模式尚不清楚，原因是缺乏断层上的主要古地震证据，以及相关的结构复杂性具有俯冲过程，并且没有发生大到特大地震的一次表面破裂。在这种情况下，在巴图巴斯蒂（南安达曼）的一条6米高断层陡坡上进行了古地震海沟初步调查，以了解俯冲带地震的滑移划分和破裂动力。探地雷达（GPR）剖面和整个陡坡上的沟渠暴露表明，渐进形变和同震陡坡产生的几次发作，其中Andaman Flysch砂岩（渐新世）与晚期全新世沉积物发生断层接触。总共观察到包括三个断层股线（F0，F1和F2）的八个地层单位（a至g）并将其绘制在沟槽地层中。OSL年龄限制了事件1沿F0发生在2312±302年BP和推力单位（g）Andaman Flysch-基岩之上的单位（f）古土壤。事件2在422±57年BP左右沿F1和F2使单元（C）-中砂床变形，单元（b）-细砂床的基础部分变形。假定陡峭高度为6 m，且沿低角度断层的单位（g）基岩的垂直位移约为3 m（θ  = 18°）意味着平均滑移率为4.12毫米/年，缩短率为3.88毫米/年，上升率为4.54毫米/年。