*2.2.1. Makran*

**2. Tsunamis**

4 Tsunami

**2.1. Tsunami sources**

The recent advances in tsunami study has lead the scientist for better understanding of the cause of tsunami, its propagation and most importantly the system of warning ahead of tsunami arrival to the vulnerable coastal area. In addition, now the secondary sources for strengthening the devastating effect of the tsunami, for example, the splay faulting, landslide

The main source for tsunami generation, however, has been identified as being the earthquake. Due to this, we will discuss here two case studies, namely the Makran (Indian Ocean) and

The other sources are classified as meteorological effects, meteotsunami. This has been discussed fully within this book on Chapter 1, and the underwater volcanic eruption as other tsunamigenic sources also being better documented and investigated on Chapter 2 of this book.

Tsunamis can also be generated by a submarine landslide, which typically occurs as a result of an earthquake [4]. A submarine landslide, rock fall or ice fall can trigger a tsunami by displacing large amounts of water. As a result, the water level rises generating tsunami.

The Papua New Guinea tsunami of July 1998 is a good example of relatively small deepwater submarine landslide, which caused devastating local tsunamis. This was triggered by a magnitude 7.1 earthquake [5]. The multibeam bathymetric study is a very useful tool in

The other sources of major risk contributors are the onshore earthquake events rather close to sea. The thick sediments at Oman Sea provide conditions for submarine landslides and slumps that can generate small tsunamis in the region. Heidarzadeh and Satake [6] showed that the tsunami observed in the northwestern Indian Ocean following the 23 September 2013 Pakistan

In addition, the splay faults mapped offshore Makran can also play an important role as tsunami strengthening factor after the major tsunamigenic event has occurred, but not as

It is very important to note that the coastal area can be affected by both local and remote-source tsunami. In the case of a local earthquake, the impact of the earthquake can be greater than the tsunami. The main tsunamigenic earthquake may cause damages to buildings and infrastructure before the arrival of the tsunami wave, with potential loss of life. Therefore, in the near coast (local) tsunami-prone area, both tsunami and earthquake effect must be

caused by the parent earthquake sources, have been advancing [3].

Great East Japan earthquake and tsunami Pacific Ocean.

identifying this type of potential submarine landslide offshore.

inland earthquakes was generated by a submarine landslide.

independent tsunami source [7–9].

considered.

From seismotectonic view point, the Makran subduction zone is characterized by the subduc‐ tion of the oceanic part of the Arabian plate beneath the Eurasian plate [8] and extends along the Gulf of Oman from the Zendan-Minab fault system near the Strait of Hormuz in the west to the Baluchistan volcanic arc in the east. It has one of the largest accretionary prisms in the world with a thick (7 km) unconsolidated sediments [10, 11], lying above a shallow dipping decollement (**Figure 1**).

**Figure 1.** Makran seismicity 1940–2015, based on USGS catalog, the location and Focal Mechanism solution of 2015 earthquake also being indicated on the figure.

From seismicity point of view, compared with other similar zone in the world The Makran subduction area has been considered as having low seismicity. But based on data from 1945 tsunami, the affected area has been classified as a tsunami-prone region [11, 12].
