New insights into the tectonic evolution of the Andaman basin, northeast Indian Ocean

Raju, K. A. Kamesh; Ramprasad, T.; Rao, P. S.; Rao, B. Ramalingeswara; Varghese, Juby

doi:10.1016/s0012-821x(04)00075-5

Cited by 180 publications

(98 citation statements)

References 34 publications

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“…In such an eventuality, the buoyancy of the root would tend to flatten the subducting plate, inhibiting the subduction process itself and the associated back arc volcanism and seismicity. We do find from Fig.1 that volcanism is indeed absent between 6 o N and 11 o N. However, it should be noted that the backarc spreading center in the Andaman sea [3] is also located between these latitudes and whether the lack of volcanism is due to the spreading processes operating along the spreading center or due to the subducting process of a basement high (NER) or both, needs to be resolved. Another possibility is that the upper part of the NER (its topography) is getting obducted or accreted to the forearc while the lower part (the root material) along with the oceanic lithosphere is getting subducted.…”

Section: Discussionmentioning

confidence: 76%

“…At some places, particularly between 8 o -11 o N, the bathymetry is quite deep, exceeding 4000 meters, and is more prominent than the trench signature at the same latitudes. The rise in bathymetry east of this forearc basin is due to the distribution of seamounts in the Andaman sea [3,8]. To the northwest, the Bengal fan sediments display a gently rising bathymetry towards north.…”

Section: Description Of Bathymetry and Gravitymentioning

confidence: 97%

“…Thick buoyant roots underlying the basement highs tend to flatten the subducting plate and thereby inhibit the subducting process. Subduction of such bathymetric highs may also have its own effect in the spreading processes in the back arc basin [3].…”

Section: Introduction and Tectonic Settingmentioning

confidence: 99%

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Geophysical characteristics of the Ninetyeast Ridge–Andaman island arc/trench convergent zone

Subrahmanyam

Gireesh

Chand

et al. 2008

Earth and Planetary Science Letters

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The convergence tectonics of the Ninetyeast ridge (NER), upon the Andaman island arctrench system is examined through an analysis of ETOPO2 bathymetry, satellite-derived free air gravity and seismic data. Oblique subduction and the buoyancy forces arising from subduction of the NER render the subduction processes near the Andaman arc highly complex. The bathymetric expression of the NER is visible up to Lat. 10 o N but seismic reflection data indicate that it extends up to about Lat.17 o N. The gravity anomalies are strongly positive over the exposed segment of the ridge but are subdued over the buried portion. There is a prominent break in the continuity of the trench gravity low, where the NER seems to impinge upon the island arc. Further, a strong curvilinear belt of negative anomalies just behind and running parallel to the island arc, associated with the forearc basin, is a dominant feature of the gravity map. An offset in the continuity of this strong negative anomaly occurs at about the same latitude where the NER seems to be converging upon the island arc. Seismic reflection data indicate that the NER is very close to the trench. Flexural modeling of the gravity anomalies for the subducting Indian ocean lithosphere, loaded by sediments and the NER, indicate that the NER is at the starting phase of its collision with the island arc and may not have started affecting the subduction process itself. We infer that the en-echelon block structure of the NER in the proximity of the convergent zone is a consequence of complex strike-slip and subduction related tectonic forces.

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Section: Discussionmentioning

confidence: 76%

Section: Description Of Bathymetry and Gravitymentioning

confidence: 97%

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Geophysical characteristics of the Ninetyeast Ridge–Andaman island arc/trench convergent zone

Subrahmanyam

Gireesh

Chand

et al. 2008

Earth and Planetary Science Letters

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“…The Central Andaman Sea basin is c. 118 km wide and is a region of active tectonics, characterized by extensional earthquakes (Kamesh Raju et al 2004;Diehl et al 2013).…”

Section: Andaman Sea Spreading Centre and Transform Faultmentioning

confidence: 99%

Chapter 13 Anatomy of the Andaman–Nicobar subduction system from seismic reflection data

Singh¹,

Moeremans²

2017

Memoirs

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The Andaman–Nicobar subduction system is the northwestern segment of the Sunda subduction system, where the Indian Plate subducts beneath the Sunda Plate in a nearly arc-parallel direction. The entire segment ruptured during the 2004 great Andaman–Sumatra earthquake (Mw=9.3). Using recently acquired high-resolution seismic reflection data, we characterize the shallow structure of the whole Andaman–Nicobar subduction system from west to east, starting from the nature of the subducting plate in the Bay of Bengal to back-arc spreading in the Andaman Sea. We find that the Ninety-East Ridge is overlain by thick continental margin sediments beneath the recent Bengal Fan sediments. The boundary between these two sedimentary units defines the plate interface. We observe evidence of re-activation of fracture zones on the subducting plate beneath the forearc, influencing the morphology of the upper plate. The forearc region, which includes the accretionary wedge, the forearc high and the forearc basin, is exceptionally wide (250 km). We observe an unusually large bathymetric depression within the forearc high. The forearc high is bounded in the east by a normal fault, whereas the forearc basin contains an active backthrust. The forearc basin is floored by the continental crust of Malayan Peninsula origin. The active sliver strike-slip fault lies in a deep basin, created during the rifting of the forearc continental crust and the Malayan Peninsula. The sliver fault connects with the Great Sumatra Fault in the south and with the Sagaing Fault in the north, via the Andaman Sea spreading centre and a large transform fault in the Andaman Sea.

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“…The formation of the East Andaman Basin and the Mergui Basin results from backarc-related extensional tectonics, active throughout the area (Chakraborty and Khan, 2009;Curray, 2005). For the development of the Andaman Sea basins multi-stage models have been suggested (Kamesh Raju et al, 2004;Curray, 2005;Kamesh Raju, 2005;Chakraborty and Khan, 2009). The area of rifting moved from the Mergui Basin over the East Andaman Basin to its current position ( Fig.…”

Section: Regional Settingmentioning

confidence: 99%

Submarine mass wasting and associated tsunami risk offshore western Thailand, Andaman Sea, Indian Ocean

Schwab

Krastel

Grün

et al. 2012

Nat. Hazards Earth Syst. Sci.

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Abstract. 2-D seismic data from the top and the western slope of Mergui Ridge in water depths between 300 and 2200 m off the Thai west coast have been investigated in order to identify mass transport deposits (MTDs) and evaluate the tsunamigenic potential of submarine landslides in this outer shelf area. Based on our newly collected data, 17 mass transport deposits have been identified. Minimum volumes of individual MTDs range between 0.3 km 3 and 14 km 3 . Landslide deposits have been identified in three different settings: (i) stacked MTDs within disturbed and faulted basin sediments at the transition of the East Andaman Basin to the Mergui Ridge; (ii) MTDs within a pile of drift sediments at the basin-ridge transition; and (iii) MTDs near the edge of/on top of Mergui Ridge in relatively shallow water depths (< 1000 m). Our data indicate that the Mergui Ridge slope area seems to have been generally unstable with repeated occurrence of slide events. We find that the most likely causes for slope instabilities may be the presence of unstable drift sediments, excess pore pressure, and active tectonics. Most MTDs are located in large water depths (> 1000 m) and/or comprise small volumes suggesting a small tsunami potential. Moreover, the recurrence rates of failure events seem to be low. Some MTDs with tsunami potential, however, have been identified on top of Mergui Ridge. Mass-wasting events that may occur in the future at similar locations may trigger tsunamis if they comprise sufficient volumes. Landslide tsunamis, emerging from slope failures in the working area and affecting western Thailand coastal areas therefore cannot be excluded, though the probability is very small compared to the probability of earthquake-triggered tsunamis, arising from the Sunda Trench.

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New insights into the tectonic evolution of the Andaman basin, northeast Indian Ocean

Cited by 180 publications

References 34 publications

Geophysical characteristics of the Ninetyeast Ridge–Andaman island arc/trench convergent zone

Geophysical characteristics of the Ninetyeast Ridge–Andaman island arc/trench convergent zone

Chapter 13 Anatomy of the Andaman–Nicobar subduction system from seismic reflection data

Submarine mass wasting and associated tsunami risk offshore western Thailand, Andaman Sea, Indian Ocean

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