# Joint Multi-Scenario-Based Earthquake and Tsunami Hazard Assessment for Alexandria, Egypt
## 4 Multi-Scenario Physics-Based Tsunami Hazard Analysis: Data and Methods
### Tsunamigenic Earthquake Sources in the Eastern Mediterranean  
The Eastern Mediterranean basin (EM) is a small oceanic basin renowned for its intricate tectonic characteristics. Geodynamical studies on the EM basin widely agree that the African plate subtends beneath Eurasia along the Hellenic Arc (HA) at a rate of approximately 1 cm/year [58]. In the northern section of the Mediterranean basin, the Aegean Sea is recognized as an extensional basin, with an opening rate of around 4.0 cm/year [59]. Moving towards the eastern part of the EM, the collision between the African plate and the Anatolia micro-plate occurs along the Cyprian Arc (CA) at a rate of 6 mm/year [59]. The ongoing conversion between African and Eurasian plates has been evidenced in both arcs using bathymetry, seismicity, and other geophysical data. From the available historical tsunami catalog, it appears that earthquakes and submarine landslides are the two primary tsunamigenic sources in the EM followed by volcanic eruptions [2]. Several tsunamis may have originated as a combination between the two different sources. Based on the spatial distribution of seismicity, tsunami activity, and present-day tectonic activity, many authors (e.g., [60]) have divided the EM into three different tsunamigenic sources, i.e., the West Hellenic (WHA) and East Hellenic (EHA) Arcs and the Cyprian Arc (CA), arranged from west to east (Figure 10). Evidently, most if not all seismotectonic studies (e.g., [60; 61]) have concluded that the WHA, EHA, and CA are the sources of worst-case scenarios as concerns sustainable development planning along the Alexandria coastline. According to the historical record of earthquakes (e.g., [13; 62]), the Hellenic Arc can be considered the source that generated the strongest earthquakes and basin-wide tsunamis that have occurred in the EM so far. Its tsunamis are considered the most hazardous source for the EM, and they are well known to produce significant destruction along the Egyptian coast, particularly the tsunamis of 365 CE and 1303 CE. The Hellenic Arc's tsunamis are generated due to the occurrence of large shallow earthquakes of vertical displacement. Many studies have discussed the history of earthquakes and tsunamis in the Hellenic Arc and evaluated their potential to generate future activities. For example, [PERSON] [63], [PERSON] and [PERSON] [64], and [PERSON] et al. [65] investigated tsunamis along the Greek coasts. [PERSON] and [PERSON] [66] found that the most devastating tsunamis occurred in areas of shallow normal and thrust faulting. [PERSON] et al. [61] found that about 18 tsunamis are documented in the EHA.  
The Cyprian Arc is the closest collision zone to the Egyptian coast but is smaller, slower, and less active than the HA. Large earthquakes triggering local to regional tsunamis in the Cyprian Arc had happened throughout history, but so far no significant basin-wide tsunami is known to have originated in this source due to its relatively small magnitude relative to the Hellenic Arc.