Temporally variable recurrence regimes of mega-tsunamis in the 6500 years prior to the 2004 Indian Ocean event

Sanwal, J and Rajendran, CP and Heidarzadeh, M and Mache, S and Anandasabari, K and Rajendran, K (2023) Temporally variable recurrence regimes of mega-tsunamis in the 6500 years prior to the 2004 Indian Ocean event. In: Marine Geology, 460 .

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Abstract

The analyses of cores retrieved from three sites near Port Blair (South Andaman) revealed out-of-sequence deposits at various depths. They are identified as previous episodes of tsunami by their sediment characteristics and microfossil content, using the 2004 event deposition as a template. These deposits have median ages of 601 cal. yr BP, 837 cal. yr BP, 1440 cal. yr BP, 3018 cal. yr BP, 3591 cal. yr BP, 4712 cal. yr BP, 5607 cal. yr BP, and 6357 cal. yr BP and are chronologically equivalent of those from the far-field locations in the Indian Ocean region. The distant deposits that are correlated with the South Andaman sites most likely owe their origin to the 2004-type events, as indicated by tsunami simulations in the study region. The long-term record presented here is characterized by an early phase of a quasiperiodic recurrence regime that transitions into a distinct interval of temporally clustered events. The quasiperiodic regime that appears around the mid-Holocene with an inter-event interval of 980 ± 385 years is followed by a sizable quiescent period of 1605 ± 245 years, before being succeeded by a regime of temporally clustered events. The chronology of nine tsunami events in the last 6500 years from the Indian Ocean region, thus implies a nonlinear pattern for the causative earthquakes. As demonstrated in the subduction zones elsewhere, the temporal variability of tsunamigenic great earthquakes is supported by the theoretical models espousing the characteristics of long-term stress recycling processes active within the subduction zones and transfer processes between the lower viscoelastic layer and the upper seismogenic crust.

Item Type:	Journal Article
Publication:	Marine Geology
Publisher:	Elsevier B.V.
Additional Information:	The copyright of this article belongs to Elsevier B.V.
Keywords:	Andamans; Andamans and Nicobars; Indian Ocean; Port Blair; South Andaman; Deposits; Oceanography; Tsunamis; Far-field; Indian ocean; Indian ocean regions; Microfossils; Out of sequences; Sediment characteristic; Subduction zones; Supercycle; The 2004 earthquake; Tsunami recurrence; earthquake; Holocene; microfossil; recycling; seismotectonics; subduction zone; temporal variation; tsunami; Earthquakes
Department/Centre:	Division of Mechanical Sciences > Civil Engineering
Date Deposited:	14 Jun 2023 07:54
Last Modified:	14 Jun 2023 07:54
URI:	https://eprints.iisc.ac.in/id/eprint/81867

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