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Trapped waves of the 27 November 1945 Makran tsunami: Observations and numerical modeling

Neetu, S and Suresh, L and Shankar, R and Nagarajan, B and Sharma, R and Shenoi, SSC and Unnikrishnan, AS and Sundar, D (2011) Trapped waves of the 27 November 1945 Makran tsunami: Observations and numerical modeling. Natural Hazards, 59 (3). pp. 1609-1618. ISSN 1573-0840

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The 27 November 1945 earthquake in the Makran Subduction Zone triggered a destructive tsunami that has left important problems unresolved. According to the available reports, high waves persisted along the Makran coast and at Karachi for several hours after the arrival of the first wave. Long-duration sea-level oscillations were also reported from Port Victoria, Seychelles. On the other hand, only one high wave was reported from Mumbai. Tide-gauge records of the tsunami from Karachi and Mumbai confirm these reports. While the data from Mumbai shows a single high wave, Karachi data shows that high waves persisted for more than 7 h, with maximum wave height occurring 2.8 h after the arrival of the first wave. In this paper, we analyze the cause of these persistent high waves using a numerical model. The simulation reproduces the observed features reasonably well, particularly the persistent high waves at Karachi and the single high wave at Mumbai. It further reveals that the persistent high waves along the Makran coast and at Karachi were the result of trapping of the tsunami-wave energy on the continental shelf off the Makran coast and that these coastally-trapped edge waves were trapped in the along-shore direction within a ~300-km stretch of the continental shelf. Sensitivity experiments establish that this along-shore trapping of the tsunami energy is due to variations in the shelf width. In addition, the model simulation indicates that the reported long duration of sea-level oscillations at Port Victoria were mainly due to trapping of the tsunami energy over the large shallow region surrounding the Seychelles archipelago.

Item Type: Article
Additional Information: Copyright of this article belongs to Springer
Uncontrolled Keywords: Tsunami Makran subduction zone Tide-gauge data Coastally-trapped waves Tsunami-hazard mitigation
Subjects: Oceanography > oceanography
Depositing User: INCOIS Library
Date Deposited: 06 Dec 2013 15:05
Last Modified: 06 Dec 2013 15:05

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