ASSESSMENT OF TSUNAMI HAZARD AND TSUNAMI RESILIENT STRUCTURE PROPOSED FOR THE COASTAL REGION OF INDIA
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Date
2026
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Department of Civil, NITS
Abstract
This study introduces a comprehensive, multi-scale framework for tsunami hazard assessment
that combines global probabilistic forecasting, geospatial vulnerability mapping, and structural
resilience analysis to guide risk-informed planning and mitigation. On a global level, a
stochastic model estimates future tsunami occurrences across 14 high-risk tsunamigenic zones,
using Conditional Probability (CP) and the Total Probability Theorem (TPT). This dual
methodology considers both mixed tsunami conditions (any wave height) and high-impact
events (wave height > 3 meters). Inter-arrival times are modelled with the best-fitting
distributions, such as Gamma, Lognormal, Weibull, and Log-logistic. The tsunami-to
earthquake ratio (r) is included in TPT calculations to account for spatial seismic-tsunamigenic
variability. Results indicate that, under mixed conditions, the highest tsunami probabilities are
in Zones 1 (Colombia, Ecuador, Brazil), 7 (Japan, China, North Korea), and 11 (Solomon
Islands, Vanuatu, New Caledonia). For high-impact tsunamis, Zones 3 (Cuba, Jamaica, Haiti),
9 (Malaysia, Brunei, Australia), and again Zone 1 show the greatest risk. This probabilistic
framework offers a robust basis for early warning systems and transnational preparedness.
A comprehensive tsunami vulnerability assessment for India’s eastern coast was performed at
the regional level, utilizing GIS-based spatial analysis combined with a multicriteria decision
making framework. Six key parameters, elevation, slope, coastal proximity, land use/land
cover (LULC), flow accumulation, and population density, were incorporated through the
Analytic Hierarchy Process (AHP) to generate detailed vulnerability maps. These maps
highlighted Nagapattinam (166.46 km²), Cuddalore (245.64 km²), Kanyakumari (37.65 km²),
Karaikal (35.71 km²), and Chennai (35.63 km²) as highly susceptible coastal zones. To enhance
these insights, connectivity overlays depicting major roads, railways, and high-elevation safe
locations were added, offering essential guidance for emergency response and sustainable
coastal development.
On the structural front, the study assessed the tsunami performance of Open Ground Storey
(OGS) G+2 reinforced concrete (RC) buildings, with a specific focus on retrofitted stepped
column designs. Using Artificial Neural Networks (ANNs) and Monte Carlo Simulations
(MCS), fragility curves were developed for three damage states: Immediate Occupancy (IO),
Life Safety (LS), and Collapse Prevention (CP). Compared to traditional RC frames, buildings
with stepped columns showed substantial performance improvements, with about a 50%
reduction in inter-storey drift and lower exceedance probabilities of 27.05% (IO), 28.57% (LS),
and 32.4% (CP). Stepped-column buildings withstood tsunami wave heights of 9.4 m (IO),
11.4 m (LS), and 12.9 m (CP), while regular RC buildings failed at lower wave heights of 7.2 m
(IO), 9.3 m (LS), and 10.6 m (CP). The study also compared square and circular stepped
column geometries, highlighting the crucial role of column shape in enhancing tsunami
resistant performance. At a 50% exceedance probability, circular columns withstood greater
wave heights of 10.3 m (IO), 12.1 m (LS), and 13.6 m (CP), outperforming square columns by
9.6%, 6.1%, and 5.5%, respectively. They also exhibited reduced inter-storey drift ratios and
delayed hinge formation, indicating superior ductility and energy dissipation. Although circular
columns involve approximately 9% higher initial construction costs, they provide long-term
economic benefits, including 5–10% reductions in overall lifecycle losses. These findings
confirm that circular stepped-column retrofits offer a cost-effective and structurally resilient
solution for tsunami-prone infrastructure.
Overall, this study integrates global tsunami forecasting, regional hazard mapping, and
performance-based structural design into a unified framework, providing practical insights for
infrastructure planning, disaster preparedness, and coastal policy-making, particularly in highly
vulnerable areas such as coastal India.