Tsunami hazard assessment of Chabahar bay related to megathrust seismogenic potential of the Makran subduction zone

Abstract

Tsunami inundation mapping is the first step in the development of effective evacuation plans for communities at risk. These maps also provide bases for land use planners in communities to reduce risk by locating critical facilities out of the potential tsunami flood plain. The Makran subduction zone, located off the Indian Ocean coasts of Iran and Pakistan, is an important tsunamigenic zone for the region. On the 27th November, 1945, it was the site of a major earthquake with a moment magnitude of 8.1 and killed about 4,000 people. This event is a proof that Makran coastal areas are unsafe since the tsunami is quite probable. The objective of this study was providing tsunami inundation and hazard maps in Chabahar bay which is located in South East of Iran and the northern coast of Oman Sea. Three different source magnitude scenarios along Makran subduction zone are considered and for each scenario, numerical modeling of tsunami propagation is performed using MIKE 21 FM numerical software. Because the Makran subduction zone is very close to the Chabahar bay, unstructured triangular mesh with a higher level of refinement closer to the area of interest was used so that the tsunami was not numerically dissipated. After analyzing the data obtained from the results, inundation maps were produced, and by combining these maps, tsunami hazard map was provided for the bay. Tsunami wave amplification has been observed mainly in the outer coasts of the bay where the uplifted rocky shore experience up to 18 m wave height. Chabahar bay omega form and two eastern and western headlands cause a considerable depreciation in tsunami wave. Longer distance of coasts within the bay is another reason of tsunami depreciation inside the bay. Based on the generated inundation and hazard maps, two flood zones are specified. The first zone associated with no inundation or low inundation on cliffy shores, and the second zone would experience extensive inundation on the coast of kenarak areas, areas with sandy beaches and gentle slope.

Numerical modelling of tsunami in the Makran Subduction Zone – A case study on the 1945 event

“…As reported in (Pararas-Carayannis 2006) by Pararas-Carayannis (2006), large earthquakes along the Makran Subduction Zone are infrequent. However, the potential for the generation of destructive tsunamis in the Northern Arabian Sea cannot be overlooked.…”

“…The destructive tsunami killed more than 4000 people in Southern Pakistan and also caused great loss of life and devastation along the coasts of Western India, Iran, Oman and possibly elsewhere. The above information was obtained from (Pararas-Carayannis 2006). Smith et al (2013) developed a 2-D thermal model of the Makran Subduction Zone.…”

The development of tsunami inundation map for Penang using TUNA-RP

“…The first wave reached the Japanese mainland 20 minutes after the earthquake and inundated more than 5 km inland [1]. It was estimated that 50% of the world's population would reside and work within the coastal zone by 2030 [2]. Therefore, the study of tsunami leading to the detection of area with high risk of tsunami plays an important role in coastal zone management.…”

Coastal Foraminifera From the Iranian Coast of Makran, Oman Sea (Chabahar Bay to Gawater Bay) as an Indicator of Tsunamis

“…Donato et al, (2008Donato et al, ( , 2009 and Pilarczyk et al, (2011 investigated shell layers, grain size distributions, and foraminifera, respectively, from the 1945 Makran tsunami in Sur Lagoon (coast of Oman). Numerical studies have also been done to assess the tsunami risk of the Makran and adjacent coastlines (Mokhtari et al, 2008;Heidarzadeh et al, 2008aHeidarzadeh et al, , 2009Okal & Synolakis, 2008;Okal et al, 2015;Jaiswal et al, 2009;Shah-Hosseini et al, 2011;Payande et al, 2015).…”