Geometry of the Subducting Indian Plate and Local Seismicity in the Andaman Region from the Passive OBS Experiment

Singha, Pabitra; Dewangan, P.; Raju, K. A. Kamesh; Aswini, K. K.; Reddy, Telluri Ramakrushana

doi:10.1785/0120180178

Cited by 24 publications

(13 citation statements)

References 62 publications

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“…We note that no high P-wave velocity anomaly is observed there (Replumaz et al, 2010;Richards et al, 2007). Further south, the slab beneath the Andaman Sea has a steep dip angle as revealed by previous seismic tomographic studies (Pesicek et al, 2010;Replumaz et al, 2010) and the spatial distribution of seismicity (Singha et al, 2019), which is similar to that observed beneath central Myanmar in this study. Recently, Mishra et al (2019) reported that the steeply subducting Indian slab beneath the Andaman Sea has penetrated through the 410-km discontinuity but terminates above the 660-km discontinuity based on their receiver function study.…”

Section: Discussionsupporting

confidence: 89%

Slab Models Beneath Central Myanmar Revealed by a Joint Inversion of Regional and Teleseismic Traveltime Data

et al. 2021

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Myanmar (Burma) occupies a complex tectonic region that plays a vital role in the geodynamic evolution of East Asia (Figure 1a). The elongated Burma Plate, which was first defined by Curray et al. (1979), connects the ongoing India-Asia continental collision along the Himalayan Range in the north to the subduction of the Indo-Australian Plate beneath the Sunda Plate in the south. The Rakhine-Bangladesh megathrust, that is, the northern extension of the Sunda megathrust, defines the western boundary of the Burma Plate, where it overrides the east-dipping Indian Plate. The Burma Plate is bounded to the east by the dextral strike-slip Sagging fault, which links to the Eastern Himalayan Syntaxis in the north and the spreading center of the Andaman Sea in the south. East of the Sagging fault lies the Shan plateau, which is accommodating distributed deformation along both sinistral and dextral strike-slip faults (Wang et al., 2014). The Burma Plate contains two noticeable north-south trending structures (Figures 1a-1b): (1) the Indo-Burman Range (IBR), which connects the Eastern Himalayan Syntaxis in the north with the Andaman-Nicobar Ridge and the outer arc ridge off Sumatra in the south; and (2) the Central Myanmar Basin (CMB), which extends southward into the central basin of the Andaman Sea. The subduction-related Indo-Burman Wedge (IBW) is bounded by the Rakhine-Bangladesh megathrust to the west and the CMB to the east (Figure 1a). The outer IBW is composed of Neogene clastic sequences affected by a series of asymmetric folds, and the inner IBW rises as the IBR (Mallick et al., 2019). The existence of an eastward dipping subduction zone beneath Myanmar has been confirmed by seismicity (e.g.,

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Section: Discussionsupporting

confidence: 89%

Slab Models Beneath Central Myanmar Revealed by a Joint Inversion of Regional and Teleseismic Traveltime Data

et al. 2021

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“…1 ). The details of the passive OBS experiment in the Andaman region are discussed in Dewangan et al (2018) 36 and Singha et al (2019) 38 . In the present study, we considered the OBS data of 21st and 22nd March 2014, when an earthquake swarm occurred in the off Nicobar region.…”

Section: Methodsmentioning

confidence: 99%

“…The picked arrival times were used for locating the earthquakes using Hypocent v.3.2 program 40 and the minimum 1D velocity model established by Singha et al (2019) 38 . We estimated the location error ellipse using a covariance matrix, as defined in the Hypocent program.…”

Section: Methodsmentioning

confidence: 99%

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Sub-surface magma movement inferred from low-frequency seismic events in the off-Nicobar region, Andaman Sea

Aswini

Dewangan

Raju

et al. 2020

Sci Rep

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Monitoring volcanic activity along the submarine volcanoes that are usually induced by subsurface magmatism is a challenge. We present fresh set of Ocean Bottom Seismometer (OBS) data that shows geophysical evidence indicative of subsurface magmatism along the submarine volcanoes in the off Nicobar region, Andaman Sea. In this region, we observed for the first time, hybrid very long-period earthquakes documented by passive OBS experiment. These events were initiated by high-frequency (5–10 Hz) with a clear onset of P-phase followed by low-frequency (0.01–0.5 Hz) oscillations in the range of 300–600 s with a prominent high-frequency (10–40 Hz) hydro-acoustic phase. A total of 141 high-frequency events were detected on 21st and 22nd March 2014 out of which 71 were of low-frequency oscillations. These events are distributed in the northwest–southeast direction along the submarine volcanic arc and Seulimeum strand of Great Sumatra fault. Off Nicobar region has been witnessing frequent earthquake swarms since 26th December 2004 tsunamigenic Sumatra earthquake. These swarms occurred in January 2005, March and October 2014, November 2015 and March 2019. The occurrence of low-frequency earthquakes and prominent hydro-acoustic phase are suggestive of sub-surface tectonic and magmatic influence. We propose that upward movement of magma pulses from deeper magma reservoir to the shallow magma chamber activated the strike-slip movement of sliver faults and induced earthquake swarms in the off Nicobar region.

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“…The latest 1D velocity models derived using ocean bottom seismometer (OBS) data from the Andaman arc region also indicates a Moho at 30 km depth and a sharp increase in the dip of the subducting Indian plate from 26° in the Nicobar segment to 53°i n the Andaman segment, deciphered by mapping the intermediate-depth earthquakes (Singha et al, 2019). They also observed a seismic gap in the subducting Indian plate between 7.5° N and 9.5° N at depths greater than 100 km, which was attributed to partial subduction of the Ninetyeast ridge.…”

Section: Andaman Subduction Zonementioning

confidence: 99%

A review of seismological research in India during the past five years (2015-2019)

Srijayanthi¹,

Kumar²,

Gahalaut³

2020

PINSA

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Geometry of the Subducting Indian Plate and Local Seismicity in the Andaman Region from the Passive OBS Experiment

Cited by 24 publications

References 62 publications

Slab Models Beneath Central Myanmar Revealed by a Joint Inversion of Regional and Teleseismic Traveltime Data

Slab Models Beneath Central Myanmar Revealed by a Joint Inversion of Regional and Teleseismic Traveltime Data

Sub-surface magma movement inferred from low-frequency seismic events in the off-Nicobar region, Andaman Sea

A review of seismological research in India during the past five years (2015-2019)

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