Abstract:
This research focuses on assessing the exposure of Sri Lanka's southwestern coast to tsunami
hazards. Tsunamis are a series of ocean waves triggered by impulsive disturbances, such as
undersea earthquakes, volcanic eruptions, landslides, and cosmic explosions. The catastrophic
impact of tsunamis, as demonstrated by the devastating Indian Ocean tsunami (IOT) event in
December 2004, underscores the urgent need for an effective early warning system to mitigate
the loss of life and property in coastal regions.
The study specifically examines the vulnerability and exposure of the southern coastline
ranging from Rathgama to Dadalla. The Community Model Interface for Tsunami (ComMIT)
is used in the research's numerical simulation. Access to a precomputed tsunami scenario
database and the MOST (Method of Splitting Tsunami) model created by the NCTR (National
Center for Tsunami Research) is made possible through ComMIT, a user-friendly graphical
interface. The model simulates tsunami waves with magnitudes ranging from 7.6 to 9.2 Mw,
originating from selected unit sources along the Sunda trench in Indonesia and the Makran fault
in Pakistan. The Sunda Arc is a volcanic arc that formed the islands of Java and Sumatra.
Makran fault is located to the northwest off the coast of Pakistan. Makran trench is less affected
relative to Sunda arc. For this research study five zones in Sunda trench and one zone in Makran
fault are taken for segmentation of unit sources.
By combining the model's output with Green's law, the research calculates the maximum wave
heights at a depth of 1 m. This data is crucial in identifying the levels of tsunami exposure
along the coastal stretch. Furthermore, it enables the accurate projection of the exposure,
facilitating the incorporation of lag-time effectively into early warning systems.
The findings of this study will contribute to enhancing the understanding of tsunami hazards
in Sri Lanka and specifically the southwestern coastal region. Exposure assessment will aid in
issuing timely and accurate warnings, minimising the potential for fatalities and injuries in
future tsunami events. Ultimately, the research aims to improve disaster preparedness and
enhance the resilience of coastal communities in Sri Lanka to mitigate the impacts of tsunamis.
