Aftershock Propagation Characteristics During the First Three Hours Following the 26 December 2004 Sumatra-Andaman Earthquake

Dasgupta, Sujit; Mukhopadhyay, Basab; Acharyya, A.

doi:10.1016/s1342-937x(05)71158-8

Cited by 11 publications

(7 citation statements)

References 3 publications

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“…The 26 December 2004 off Sumatra earthquake (Mw 9.3) is such a large one which has provided an opportunity to understand the features like rupture evolution, co-and post-seismic deformation and many other tectonic phenomena (Ammon et al 2005;Ishii et al 2005;Lay et al 2005;Kreemer et al 2006;Subarya et al 2006;Khan 2007); the study also helps in identifying new faults that are originated due to the internal deformation of the Indian plate caused by the said earthquake. The rupture propagation character, the rupturing processes and tsunami generation have been understood in terms of along-trench change in plate geometry as well as plate driving forces (Dasgupta et al 2005;Ishii et al 2005;Kr€ uger & Ohrnberger 2005;Lay et al 2005;Khan 2007Khan , 2010. Furthermore, the dip and age of subducting plate, plate obliquity, subduction rate, etc.…”

Section: Tectonics Present Crustal Motions and Earthquake Generationmentioning

confidence: 99%

Slab tear and tensional fault systems in the Sunda–Andaman Benioff zone: implications on tectonics and potential seismic hazard

Mukhopadhyay

Dasgupta

Mukherjee

2015

Geomatics, Natural Hazards and Risk

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Transverse slab tear faults and longitudinal trench parallel extensional faults present on the top part of Benioff zone in SundaÀAndaman arc between latitude 6 À15 N and longitude 90 À98 E are marked by seismotectonic analysis using contemporary data related to regional tectonics, seismicity, centroid moment tensor (CMT) fault plane solutions, etc. Characteristics of ten numbers of transverse slab tear faults is taken from our previous studies, whereas four numbers of longitudinal trench parallel extensional faults are marked by the present study. These two sets of fault systems make high angle between them and tectonically complement each other. The disposition, origin, tectonic framework, depth of penetration and seismotectonic evaluations of the fault systems are analyzed. An effort is made to identify the potential seismic hazard in the zone between trench and forearc containing Andaman Group of Island.

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Section: Tectonics Present Crustal Motions and Earthquake Generationmentioning

confidence: 99%

Slab tear and tensional fault systems in the Sunda–Andaman Benioff zone: implications on tectonics and potential seismic hazard

Mukhopadhyay

Dasgupta

Mukherjee

2015

Geomatics, Natural Hazards and Risk

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“…The moment magnitude of Mw 9.3 (Krüger and Ohrnberger 2005) with average slip of around 7-10 m and varying width of 160-240 km of the rupture zone has been modelled (Stein and Okal 2005;Lay et al 2005). Focal mechanisms of the aftershocks indicate predominant thrust earthquakes in the fore-arc region and strike slip to normal faulting in the back-arc region (Dasgupta et al 2005). The precursor study carried out by us has identified a 50-day shortterm quiescence with a high b value zone surrounding the epicentre preceding the main shock (Dasgupta et al 2007).…”

Section: Introductionmentioning

confidence: 99%

“…It is interesting to note that the entire plate interface (with rupture length 1,200 km ? and width 160-240 km) has been ruptured within the first hour of aftershock propagation (Dasgupta et al 2005), and pore-pressure perturbation front was active to generate aftershocks located along the entire rupture zone from Sumatra to north of Andaman Island. In the subsequent hours, the pore-pressure perturbation front was restricted within the rupture area (length 1,200 km ?…”

Section: Introductionmentioning

confidence: 99%

Modelling the pore fluid diffusion process in aftershock initiation for 2004 Sumatra earthquake: implications for marine geohazard estimation in the Andaman region

et al. 2011

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The role of fluid injection on the occurrence and migration path for the aftershocks of 2004 Sumatra earthquake (Mw 9.3) and January 2005 Andaman earthquake swarm within the aftershock sequence is investigated here from the viewpoint of pore fluid diffusion process. The Sumatra earthquake created a regionally extensive crustal rupture plane exceeding 1,200 km length below the Andaman Sea. The r-t plots (Shapiro et al. 1997) are constructed for these aftershocks in order to examine the role of poroelastic effects as rupturing progressed with time. Their main results are as follows: the r-t plot corresponding to first 3 h of aftershock activity (when only 44 events of mb C 4.5 originated) reveals that 95% of the data points occurred below the modelled parabola with relatively high D value of 20 m 2 /s, whereas a significantly low D value of 3.5 m 2 /s characterises the aftershock activity for the first 24 h (when 420 events of mb C 4.0 occurred). Here, the Coulomb stress was transferred from the main shock with a rapid imposition of normal stress, thus inducing the pore-pressure change that started diminishing almost immediately by fluid diffusion, at a rate, defined by the diminishing D value. The modelling results for fault seismicity at far off distances from the main epicentre are interpreted here as potential indicators for large-scale sub-seabed rupturing-consequent to stress changes induced by bending of the Indian Ocean plate. Bathymetric slopes under the Andaman subduction zone are particularly amenable to sub-marine slides where crustal E-W hinge faults inferred seismically cut across the N-S trending regional thrust and strike-slip faults. Seabed rupturing appears to allow deep-slab hydration in these areas, producing pressure gradients along the normal faults. These features are important since they can herald marine geohazards in the Andaman region.

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“…Recurrence of major seismic energy bursts (Ishii et al 2005), activation of three isolated fault segments in the southern, central and northern part (Dasgupta et al 2005), and identified high stress condition (Mishra et al 2007;Walter and Amelung 2007) along the Andaman-Sumatra margin during the 2004 event do not support the sectorspecific stationarity of coupling arises from seamounts/ asperity subduction (Dmowska et al 1996). Instead, the 2004 event can be identified in the backdrop of minimum stress obliquity (Khan 2007), lowest flexing depth, shallowest dip angle, and two-stage opening of Andaman Sea from the off Sumatra area (Khan and Chakraborty 2005).…”

Section: Introductionmentioning

confidence: 99%

Role of unbalanced slab resistive force in the 2004 off Sumatra mega-earthquake (M w > 9.0) event

Khan

2010

Int J Earth Sci (Geol Rundsch)

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Present study addresses the role of major platedriving forces, particularly the slab pull and slab resistive forces, for the generation of 26 December 2004 M w [ 9.0 off Sumatra megathrust earthquake. Major controls on the plate-driving forces are normally visualized through age, speed, and average dip of the slab during subduction. Wide variation in age, plate obliquity, stress obliquity, subduction rate, dip angle, and flexing depth of the subducting oceanic lithosphere between Andaman and Sumatra thus allowed us for quantitative evaluation of the slab pull (F SP ) and slab resistive (F SR ) forces in three well-defined sectors (I, II and III). Computed values of these forces in the three sectors: (1) F SP = 1.29 9 10 13 N/m, F SR = 1.41 9 10 13 N/m; sector I, (2) F SP = 2.10 9 10 13 N/m, F SR = 1.13 9 10 13 N/m; sector II, and (3) F SP = 2.08 9 10 13 N/m, F SR = 2.72 9 10 13 N/m; sector III clearly suggest a spatial variation of stress regime in the subducting oceanic lithosphere. Excess F SR in sectors I and III are interpreted as the causative forces behind the triggering of major seismic energy bursts near Sumatra and Andaman on 26 December 2004. A gap of minimum seismic energy burst near Great Nicobar possibly was controlled by the excess of F SP in sector II. This study further advocates that the cyclic stress, resulted from unbalanced component of slab resistive force, had a definite control on the occurrence of 2004 off Sumatra megathrust earthquake around the flexing zone of the subducting lithosphere.

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Aftershock Propagation Characteristics During the First Three Hours Following the 26 December 2004 Sumatra-Andaman Earthquake

Cited by 11 publications

References 3 publications

Slab tear and tensional fault systems in the Sunda–Andaman Benioff zone: implications on tectonics and potential seismic hazard

Slab tear and tensional fault systems in the Sunda–Andaman Benioff zone: implications on tectonics and potential seismic hazard

Modelling the pore fluid diffusion process in aftershock initiation for 2004 Sumatra earthquake: implications for marine geohazard estimation in the Andaman region

Role of unbalanced slab resistive force in the 2004 off Sumatra mega-earthquake (M w > 9.0) event

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