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Tsunami in the Gulf of –initial damage evaluations at selected sites along the coast

Dr. Finzi Yaron, Ms. Shrem Cohen Suzy, Mr. Harlev Noam, Mr. Gat Itai, Dr. Ginat Hanan

The and Arava Science Center, Tamar Regional Council, Dead Sea 86910, Phone: 08-6539242, Mail: [email protected]

Abstract In recent decades, tsunamis have taken the lives of hundreds of thousands of people, left millions homeless and caused severe damage to many coastal nations. Tsunami hazard in The Gulf of Eilat is considered significant given the expectation of strong earthquakes in the region, the steep slopes in the gulf and indications of at least three past tsunamis. However, to date, no tsunami damage evaluations have been carried out in Eilat. This paper presents preliminary estimates of the possible economic impact a tsunami may have in selected sites in Eilat. Scenario representations reveal that a tsunami with inundation of 3-5 meters above sea level can cause extensive economic damage to tourist sites, commercial areas and to the port of Eilat. Such a large tsunami occurring on a weekend in peak season might harm tens of thousands of people and cause damage costing more than a billion shekel. Ongoing research must be conducted to yield more detailed tsunami scenarios and damage estimations and to help authorities devise tsunami preparation and evacuation plans.

Keywords: Tsunami, Gulf of Eilat, natural disasters, Dead Sea Transform.

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1. Introduction

Historical knowledge about tsunami events in Eilat is limited and the risk of tsunamis has been generally ignored. Nevertheless, in 1995, a magnitude 7.2 earthquake occurred south of Eilat inducing a tsunami of about one meter (Shamir et al., 1996; Wust, 1997). In addition, geologic evidence of the possible occurrence of a greater tsunami 2400 years ago was recently uncovered (Shaked et al., 2004; Tchernov et al., 2016). Furthermore, the steep structure of the Gulf of Eilat and its deep basins indicate that normal faulting is a significant component of the gulf's fault system, and that its tectonic activity and earthquake frequency are quite high (Hartman et al., 2014). Considering the fact that even a medium-sized earthquake could cause a tsunami by inducing vertical sea floor displacement or an underwater landslide, it is reasonable to assume that sooner or later a tsunami will occur in the Gulf of Eilat.

2. Methods of analysis of tsunami related damage:

A preliminary assessment of tsunami damage is achieved here based on a simplified model of a tsunami as a marine flood (causing severe damage to structures below the maximum inundation height). Such an assessment does not account for local wave amplification or flow dynamics, however, it yields a range of damage estimates for chosen locations without requiring information on the source, propagation path and amplification factors of the tsunami (Suppasri et al., 2001; Tinti et al., 2011). This approach is useful in producing first order evaluations of potential damage where numerical scenarios have not yet been interpreted in terms of financial damage. Precise and updated topographical data (LIDAR, 15 cm vertical precision, spatial resolution of 1 m2) enables accounting for embankments, trees and structures that affect the extent of inundation (Gat, 2014).

3. Results: tsunami damage at selected sites along the shores of Eilat:

Figures 1-4 present the inundation extent a large tsunami (3-5 m inundation height) at three locations in Eilat. 3

Figure 1. Location map. Eilat and Aqaba are indicated as well as sites mentioned in the article.

Along the north promenade of Eilat, adjacent to the Dan Hotel, inundation extent calculations reveal that a tsunami inundation of two meters high could cause some damage to the small buildings along the boardwalk but not to most hotels which are built at least three meters above sea level. Inundation of to five meters above sea level will flood the promenade, shops and cafes and harm the ground level of a number of hotels along the promenade, although probably not at the Dan which is built at a level of about 5 m above sea level (Fig. 2). While direct structural damage here may not be severe, indirect impact due to loss of tourist related income might still be significant and long lasting (Orchiston, et al., 2012; Droucher, 1994; Sonmez and Graefe, 1998; Huang et al ., 2002; Ichinosawa, 2006).

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Figure 2. Tsunami inundation of the north coast promenade, Eilat. The results of the five meters inundation scenario (right) and an image of the coast (left). The flooded area is painted pink, the yellow line represents the promenade and the Dan Hotel is indicated.

The Underwater Observatory and the Interuniversity Institute at the southern coast of Eilat will not experience significant damage following inundation of less than two meters. However, a 5- meter tsunami inundation height would completely flood these sites (Fig. 3). As many of the observatory structures are old and not designed to withstand inundation, the Underwater Observatory CEO - Mr. Yossi Ani has estimated that in a tsunami, damaged infrastructure will probably include the two main halls, the observatory tower and underwater viewing platform, the pedestrian bridge, the central building and all aquariums and pools. Such inundation, at the Interuniversity Institute would completely flood the majority of research and service rooms and the harbor's infrastructure. To estimate the cost of direct damage to the observatory following a 5 m tsunami inundation, it is therefore assumed that all site systems and infrastructure will be partly or completely damaged. The cost of damage therefore corresponds to the sites insured value which is 70-80 million NIS (Mr. Yossi Ani, pers. Com., 2016). The cost estimate of the total damage to Interuniversity Institute equipment and structure is expected to range from 60 to 80 million NIS (Prof. Amatzia Genin, personal communications). In addition to direct damage and loss of lives, an estimated 40 million NIS in yearly loss of income was calculated by multiplying the annual number of visitors to the Observatory by the entry cost (70 shekels) and additional revenues. Finally, irreversible damage to the corals and fauna, which are the main tourist attraction, are expected to result in a significant long-term revenue loss. 5

Figure 3. Tsunami inundation along the southern coast of Eilat: The Underwater Observatory and Inter-University Institute. Right - the flooded area assuming 5 meter inundation height (pink, bold red contour – current coastline), left - aerial photograph of the area.

At the Port of Eilat, docks are built at about 1.5 m above sea level, and therefore a small tsunami may not cause much damage. However, a large tsunami will flood large areas of the port and cause damage to docks and storage areas (Fig. 4). To evaluate the economic damage from a five meter tsunami inundation height, the cost of port facilities, offices, storage equipment, and inventory was assessed. For example, the cost of cranes and peer equipment is about 70 million shekel (book value; Gca.gov.il., 2011). In addition, there may be damage to goods at the port including phosphate and potash, containers and cars. There are thousands of cars (valued at hundreds of millions of shekels) on the lower level of the port that are likely to be damaged by a large tsunami. The overall cost of damage to the port may be evaluated based on the ports value in 2012 (130-170 Million NIS). An alternative estimate can be based on the cost of infrastructure and vessels (70 and 125 Million NIS, respectively). Loss due to business interruption is estimated from the port’s 2012 reports on yearly net profit (17 Million NIS). In addition to the vast damage, the lives of 200 port workers are at risk from a large tsunami. 6

Figure 4. Tsunami inundation along the Port of Eilat - the results of inundation calculations for 5 and 3 m inundation heights (bright pink and purple, respectively). A five meter inundation would hit most of the area east of the road and cause significant damage.

4. Preliminary conclusions

It is possible that a tsunami of three to five meters will eventually hit Eilat and cause substantial damage. The total direct financial damage to sites presented in this work (for 5 m inundation height), is estimated at 500 million NIS (not including the value of goods that may be damaged in the port of Eilat). The loss of income in the three selected sites is estimated at approximately 100-200 million NIS for the first year after the disaster. Indirect damage to businesses and residents dependent on the tourism industry may last a very long time and is difficult to estimate (e.g. Orchiston, et al., 2012; Huang et al., 2002; Ichinosawa, 2006). Tsunami damage is expected to have the largest impact on commercial and tourism entities (as opposed to earthquake damage which is expected to inflict more damage to private properties).

A survey in Eilat and regional schools revealed a lack of awareness to tsunami risks in Eilat (Gat, 2014). Local and national education programs, media broadcasts and street signs are suggested as simple ways to educate residents and visitors about tsunamis and evacuation procedures. Enhancing awareness and defining effective emergency procedures for individuals and companies may significantly reduce damage and human loss. Further research on local risk factors is required to aid determination of preferred evacuation routes and emergency procedures to reduce the impact of future tsunamis. 7

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