Emergency preparedness in the case of Makran tsunami: a case study on tsunami risk visualization for the western parts of Gujarat, India

Abstract

The west coast of India is affected by tsunamigenic earthquake along the Makran subduction zone. On 28 November 1945 at 21:56 coordinated universal time (UTC), a massive Makran earthquake (M8.0) generated a destructive tsunami that propagated across the Northern Arabian Sea and the Indian Ocean. This tsunamigenic earthquake was responsible for the loss of life and great destruction along the coasts of India, Pakistan, Iran and Oman. Modelling of tsunami stages has been made for the coasts of Pakistan, Iran, India and Oman using NAMI-DANCE computer code. The fault parameters of the earthquakes for the generation of tsunami are epicentre (25.15° N, 63.48° E), fault area (200 km length and 100 km width), angle of strike, dip and rake (246°, 7° and 90°), focal depth (15 km), slip magnitude (7 m). The bathymetry data are taken from General Bathymetric Chart of the Oceans (GEBCO) and land topography data were collected using Shuttle Radar Topography Mission (SRTM). The present simulation is carried out for a duration of 360 min. It is observed that the maximum calculated tsunami run-ups were about 0.7–1.1 m along the coast of Oman, 0.5 m near Muscat, 0.1 m near Sur, 0.7–1.35 m along the western coast of India, 0.5–2.3 m along the southern coast of Iran and 1.2–5.8 m along the southern coast of Pakistan. After the tsunamigenic earthquake, the tsunami wave reached the Gulf of Kachchh in about 240 min, Okha in about 185 min, Dwarka in about 150 min, Porbandar in about 155 min, Mumbai in about 300 min and Goa in about 210 min. The calculated 2-hr tsunami travel time to the Indian coast is in good agreement with the available reports and published data. If the tsunami strikes during high tide, we should expect more serious hazards which would impact local coastal communities. The results obtained in this study are converted to be compatible with the geographic information system based applications for display and spatial analysis of modelling results. The paper also presents classification of tsunami risk zones based on elevation vulnerability. We expect that the results presented here will be supportive to the tsunami emergency response system and useful in planning the protection measures due to tsunami.