A peak-over-threshold approach for the numerical modeling of 26 December 2004 Indian Ocean Tsunami at the Kalpakkam coast, Tamil Nadu, India

Abstract

ABSTRACT The Boxing Day tsunami of 26 December 2004 wreaked substantial havoc along the east coast of India. Repetition of an event with similar or greater magnitude will undoubtedly affect the coastal regions of India with much more severity. Precise estimation of tsunami wave heights along the coastal belts would be very important for a Risk Based Decision Making (RBDM) system. Kalpakkam located in the east coast of India, a region of strategic national interest is chosen for this study. In this study, the relevant earthquake data was extracted from NOAA-NCEI for the geographical region bounded between 92.96° E, 14.14° N to 105.75° E, 5.89°N covering regions such as Sumatra Fault, Java Trench, and Spreading Ridge in the Andaman Sea. This study examined 89 earthquake events from 1770 to 2013. The preliminary data on significant earthquake parameters viz; moderate damage, death toll exceeding a total of 10, earthquake magnitude of 7.5 or greater, modified Mercalli intensity of 10 or greater, earthquakes that generated a tsunami were subjected to Peak-over-Threshold (POT) analysis using Generalized Pareto Distribution (GPD) for varying thresholds. Thereafter, the study performed computations of five different earthquake magnitudes corresponding to return periods of 10, 102, 103, 104 and 105 years. Using Mansinha deformation model and SWAN code, tsunami simulations were carried out for all the five different scenarios. In addition five different locations were identified to estimate the tsunami heights considering Kalpakkam as the nodal point. With availability of accurate near-shore bathymetry, a more detailed study can be attempted for coastal inundation characteristics arising from future tsunamigenic events.