Abstract
Historical records of major earthquakes in the northwestern Indian Ocean along the Makran Subduction Zone (MSZ) indicate high potential tsunami hazards for coastal regions of Pakistan, Iran, Oman, and western India. There are fast-growing and populous cities and ports that are economically important, such as Chabahar (Iran), Gwadar (Pakistan), Muscat (Oman), and Mumbai (India). In this study, we assess the tsunami hazard of the 1945 MSZ event (fatalities ≈300 people) using stochastic earthquake rupture models of Mw 8.1–8.3 by considering uncertainties related to rupture geometry and slip heterogeneity. To quantify the uncertainty of earthquake source characteristics in tsunami hazard analysis, 1000 stochastic tsunami scenarios are generated via a stochastic source modeling approach. There are main objectives of this study: (1) developing stochastic earthquake slip models for the MSZ, (2) comparing results of the simulation with the existing observations of the 1945 event, and (3) evaluating the effect of uncertain fault geometry and earthquake slip based on simulated near-shore wave profiles. The 1945 Makran earthquake is focused upon by comparing model predictions with existing observations, consisting of far-field tsunami waveforms recorded on tide gauges in Karachi and Mumbai and coseismic deformation along the Pakistani coast. The results identify the source model that matches the existing observations of the 1945 Makran event best among the stochastic sources. The length, width, mean slip, and maximum slip of the identified source model are 270 km, 130 km, 2.9 m, and 19.3 m, respectively. Moreover, the sensitivity of the maximum tsunami heights along the coastline to the location of a large-slip area is highlighted. The maximum heights of the tsunami and coseismic deformation results at Ormara are in the range of 0.3–7.0 m and −2.7 to 1.1 m, respectively, for the 1000 stochastic source models.
Highlights
Great tsunamis are capable of destroying coastal cities and towns
We evaluate the effects of earthquake slip and fault geometry on tsunami simulation results by investigating coastal tsunami heights along Iran and Pakistan
The results highlight the sensitivity of the maximum coastal tsunami heights along the coastline to the location of a large-slip area of the source models
Summary
Great tsunamis are capable of destroying coastal cities and towns. In the last two decades, the 2004Indian Ocean tsunami and the 2011 Tohoku (Japan) tsunami caused significant damage and death tolls. Great tsunamis are capable of destroying coastal cities and towns. In the last two decades, the 2004. Indian Ocean tsunami and the 2011 Tohoku (Japan) tsunami caused significant damage and death tolls. The 2004 Indian Ocean tsunami claimed more than 220,000 fatalities [1]. The 2011 Tohoku event caused ≈20,000 deaths, and its economic loss was estimated at US$ 211 billion in direct damages [2,3]. Tsunamis have been considered as more extreme than other types of natural hazards [4]. The Makran Subduction Zone (MSZ; Figure 1) of offshore Iran and Pakistan is one of the less-studied tsunamigenic zones in the world, having high potential to generate catastrophic tsunamis
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