Historical tsunami in the Makran Subduction Zone off the southern coasts of Iran and Pakistan and results of numerical modeling

Abstract

Tsunami hazard in the Makran Subduction Zone (MSZ), off the southern coasts of Iran and Pakistan, was studied by numerical modeling of historical tsunami in this region. Although the MSZ triggered the second deadliest tsunami in the Indian Ocean, among those known, the tsunami hazard in this region has yet to be analyzed in detail. This paper reports the results of a risk analysis using five scenario events based on the historic records, and identifies a seismic gap area in western Makran off the southern coast of Iran. This is a possible site for a future large earthquake and tsunami. In addition, we performed numerical modeling to explain some ambiguities in the historical reports. Based on the modeling results, we conclude that either the extreme run-up of 12-15 m assigned for the 1945 Makran tsunami in the historical record was produced by a submarine landslide triggered by the parent earthquake, or that these reports are exaggerated. The other possibility could be the generation of the huge run-up heights by large displacements on splay faults. The results of run-up modeling reveal that a large earthquake and tsunami in the MSZ is capable of producing considerable run-up heights in the far field. Therefore, it is possible that the MSZ was the source of the tsunami encountered by a Portuguese fleet in Dabhul in 1524.

Statistical Analysis of Earthquakes and Tsunami of Makran Subduction Zone (MSZ), and Tsunami Hazard Assessment of Gwadar Coast

“…This tsunami event was recorded on instrument for the first time in this region. This was the only event in MSZ for which the data of the magnitude of earthquake and run-up heights in different coasts is recorded [9][10][11][12][13][14][15]. The tsunami hazard parameters of 1945 earthquake are as follows:…”

“…The tsunami was also recorded at Muscat and Gawader. This is the only event in Makran subduction zone for which the instrumental data is available such as data about the magnitude of earthquake and run-up values at different coasts [9]. …”

Owen Ridge deep-water submarine landslides: implications for tsunami hazard along the Oman coast

“…Arabian Sea coasts have been affected by numerous and disastrous tsunamis in the past (Jourdan, 2008;Heidarzadeh et al, 2008;Donato et al, 2008Donato et al, , 2009Jaiswal et al, 2009;Pilarczyk et al, 2011;Pilarczyk and Reinhardt, 2012) and storm waves from cyclones (Fritz et al, 2010). The main tsunami source in the Arabian Sea is the seismic activity of the Makran subduction zone, which caused the 1945 event (M w = 8.1) and the subsequent 4000 human fatalities.…”

Major Tsunami Risks from Splay Faulting

“…This zone extends east from the Strait of Hormoz in Iran to near Karachi in Pakistan with a length of about 900 km. The reasons that we have chosen the MSZ for our case study are twofold: firstly, Heidarzadeh et al (2008) presented evidence that a splay fault may have been responsible for the huge runup heights observed in the near field during the Makran earthquake and tsunami of November 27, 1945, and secondly, Mokhtari et al (2008) showed that many splay faults are present in the MSZ using 2D seismic reflection profiles. Figure 7 is an example of the 2D seismic reflection profiles presented by Mokhtari et al (2008).…”