Geomorphology of submarine channel-levee system in the northernmost segment of the Andaman Backarc Basin, Andaman Sea

High resolution Multibeam survey and sub-bottom profiler study in the tectonically active part of the Andaman Backarc basin depict two active channels and seven abandoned channels. Abandoned channels illustrate an extensive meandering pattern with a well-developed levee system. The most extended channel (CH-1) is a faultcontrolled channel, which runs through 168 km and displays an immature morphology in the middle section with low sinuosity. CH-5 is another active meandering to the sinuous channel, and it follows the trend of the marginal fault present in the Segment D of Andaman Backarc Basin (ABB). In contrast, the channels to the north of Segment D have undergone a long evolutionary history with numerous abandoned meanders, meander cutoffs, and evidence of progressive channel migration. Channel-2 (CH-2) and Channel-3 (CH-3) are categorized into antecedent drainages as they show the signature of flow against the present-day general slopes. CH-2 was a distributary of CH-3 and was abandoned due to the NE-SW shifting fault trails of the Sagaing fault splay. The subbottom profile reflectors, showing broad, low amplitude single hyperbola with semi-parallel internal reflectors indicate lateral migration of gravity-driven sediment waves on either side of the channels CH-1, CH-2, and CH-3. The channel levee system in the northern part of the Andaman back-arc basin displays a structurally controlled complex channel levee system similar to that of the Irrawaddy River in the upstream regime.