Seismotectonic evaluation of off Nicobar earthquake swarms, Andaman Sea

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

doi:10.1016/j.jseaes.2021.104948

Cited by 10 publications

(4 citation statements)

References 60 publications

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“…Studies on long term quiescence before 2004 earthquake was also carried out by other researchers (25) . Magmatic pulsations can result in earthquake swarms in volcanically active areas such as Off Nicobar region (6) . Our analysis shows that the northern segments are comparatively quiet since the megathrust earthquake which can lead to a major earthquake in the near future.…”

Section: Discussionmentioning

confidence: 99%

“…The fault systems divide Andaman Sea into Shallow fore arc and deeper back arc regions. The Andaman Sea has also experienced a number of earthquake swarms in 2014, 2015 and 2019 after the megathrust earthquakes a result of complexity in tectonic deformation (6) . West Andaman Fault (WAF) and the Sumatra fault system (SFS) form the boundary between Burma plate and Sunda plate south of the spreading ridge.…”

Section: Introductionmentioning

confidence: 99%

“…It may be never possible to predict an earthquake absolutely, we still have scope for identifying precursors which can be useful as part of an early warning system. Seismic quiescence analysis has shown promising results in identifying precursory abnormalities (1,3,4,6,12,13) . The objectives of the present study are proposed as understanding precursors like https://www.indjst.org/ temporal quiescence, seismicity pattern, earthquake occurrence rate, and changes in temporal 'b' values to provide additional information regarding the seismic potentiality and future seismic hazard in Andaman-Sumatra region.…”

Section: Introductionmentioning

confidence: 99%

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Seismotectonics of Andaman-Sumatra Region: Seismic Quiescence and B Value as Possible Precursors

Anjana¹,

Lasitha²

2023

IJST

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Objectives: a) To analyze the long-term seismicity and understand the potential of seismic quiescence study to use it as a reliable seismic precursor b) To estimate B value and understand the variation in B value as earthquake precursor in seismically active region. Methods: The present study analyses the seismicity pattern from the Andaman-Sumatra region for a period of 1964 to 2018. The area has been divided into epicentral blocks. Earthquakes preceding and succeeding a major earthquake with different seismic phases of quiescence and pattern of seismicity have been studied carefully. All quiescence periods are characterized by high b values and period of major shocks has a low b value. Main shock events for each epicentral block with different phases of quiescence (Q1, Q2 and Q3) and active seismicity have been identified and analyzed. Findings: The study suggests that there is generally approximately 6-12 years of gap between major earthquakes. There are 28 years of quiescence before the major earthquake of the stature of Dec 26, 2004 mega earthquake, suggesting that long term quiescence leads to great earthquakes. The study also proposes that the area between 2 0 and 6 0 N latitudes shows a long-term quiescence which may lead to a major earthquake in the near future. A thorough analysis of long-term seismicity and seismic quiescence can be used as an earthquake precursor, though with limitations. The latest post seismic quiescence period Q2 after the greater events of 2004 and 2005, may yield an impending event of 6.5 M or even greater. Novelty: The present study deals with the precursor studies of one of the most important tectonic zone. Extensive analysis of 54 Years of data has been done and the scope of using seismicity and b value for the long-term prediction of earthquakes has been examined. The periodicity of seismicity has been used to quantify the precursors. Though various statistical studies have been attempted for this zone, methodology adopted here proved one of the reliable methods to check for the possible mega earthquakes of this seismically active zone, which can be applied to other seismically active areas as well.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Seismotectonics of Andaman-Sumatra Region: Seismic Quiescence and B Value as Possible Precursors

Anjana¹,

Lasitha²

2023

IJST

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“…The earthquakes in the northern part are predominantly strike-slip, while those toward Sumatra are both strike-slip and thrust (Kamesh Raju et al, 2007). Aswini et al (2021) have analysed the earthquake swarms in the Nicobar region following the 26 th December 2004 (9.1 Mw), which were reactivated again after the 21 st March 2014 (6.5 Mw) and proposed that a combination of magmatic pulsation in the arc volcanism in response to 2004 and 2005 megathrust events and reactivation of sliver fault systems, are the dominant mechanisms for the observed frequent earthquake swarms (Figure 1). Therefore, since the Andaman-Nicobar region is very active seismic zone, the present study focuses to study the geomagnetic signal recorded in the proximity of active area in search of EM signatures associated with lithospheric deformation.…”

mentioning

confidence: 99%

Investigation of geomagnetic field variations in search of seismo-electromagnetic emissions associated with earthquakes in subduction zone of Andaman-Nicobar, India

Prajapati,

Arora

2024

Preprint

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The study of seismo-electromagnetic (EM) emissions has the potential to provide new insights into the physics of seismic activity and improve our ability to monitor and predict earthquakes and other geophysical events. Continuous recording and monitoring of EM fields in seismically active areas are very complex, but it can open a new regime in the field of earthquake prediction. In this study, one year of ground based geomagnetic data during March 2019 to April 2020 in seismic active subduction zone of Andaman-Nicobar region in search of EM signatures related to lithospheric processes. An anomalous signature in the vertical component of geomagnetic field is preferred to study after removing the global and seasonal effect from the data. Apart from vertical component of geomagnetic field, polarization ratios which also include horizontal component, also studied from spectral density with the same purpose in ULF range. Over the duration of one year, we noted an 80% enhancement in polarisation ratios and 67% deviations in diurnal ratios average 18 days before of earthquake events. Apart from that, the significant enhancements in diurnal and polarization ratio were shown to be successfully correlated with 11 out of 14 earthquakes which is equivalent to approximately 78% success ratio.

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Gas migration signatures over the volcanic cratered seamount, off the Nicobar Islands in the Andaman Sea

Sriram,

Dewangan,

Yatheesh

et al. 2023

Geo-Mar Lett

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Seismotectonic evaluation of off Nicobar earthquake swarms, Andaman Sea

Cited by 10 publications

References 60 publications

Seismotectonics of Andaman-Sumatra Region: Seismic Quiescence and B Value as Possible Precursors

Seismotectonics of Andaman-Sumatra Region: Seismic Quiescence and B Value as Possible Precursors

Investigation of geomagnetic field variations in search of seismo-electromagnetic emissions associated with earthquakes in subduction zone of Andaman-Nicobar, India

Gas migration signatures over the volcanic cratered seamount, off the Nicobar Islands in the Andaman Sea

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