Study and numerical modeling of 1945 Makran tsunami due to a probable submarine landslide

The Makran subduction zone (MSZ), located along the southern coasts of Iran and Pakistan, has experienced some deadly earthquakes and tsunamis, including the destructive 1945 Makran tsunami that led to more than 4000 fatalities. In spite of past studies on 1945 Makran tsunami, there are still unresolved problems, particularly on mismatches between the tsunami wave heights and arrival times with reported observations at different locations. The significant disagreement between the results of numerical models and existing data supports the existence of another mechanism involved during the generation of the tsunami. In the present study, a submarine landslide, triggered by the 1945 Earthquake, is studied as the major source of 1945 Makran tsunami. The simulation of seismic 1945 Tsunami, using high-resolution bathymetry data with a fine nested grid to increase the accuracy of modeled tsunami wave heights, confirms the large discrepancies between the reported tsunami waves and simulated values. Assuming the location and dimensions of a probable landslide, the GEOWAVE model, a combination of TOPICS and FUNWAVE models, is applied to model the non-seismic 1945 Tsunami. The simulated landslide tsunami demonstrates a fair agreement with the reported tsunami wave heights at different locations in Pakistan, Iran and India. The arrival times of tsunami waves at Pasni and Karachi in Pakistan can also be interpreted if the occurrence time of the probable submarine landslide is assumed with 3.5 h delay after the quake. The study highlights the potential danger of a non-seismic landslide tsunami in unconsolidated sediments at the MSZ and the necessity of the development of suitable countermeasures against other potential Makran tsunamis in future.