The Making of the NEAM Tsunami Hazard Model 2018 (NEAMTHM18)

ABSTRACT: The NEAM Tsunami Hazard Model 2018 (NEAMTHM18) is a probabilistic hazard model for tsunamis generated by earthquakes. It covers the coastlines of the North-eastern Atlantic, the Mediterranean, and connected seas (NEAM). NEAMTHM18 was designed as a three-phase project. The first two phases were dedicated to the model development and hazard calculations, following a formalized decision-making process based on a multiple-expert protocol. The third phase was dedicated to documentation and dissemination. The hazard assessment workflow was structured in Steps and Levels. There are four Steps: Step-1) probabilistic earthquake model; Step-2) tsunami generation and modeling in deep water; Step-3) shoaling and inundation; Step-4) hazard aggregation and uncertainty quantification. Each Step includes a different number of Levels. Level-0 always describes the input data; the other Levels describe the intermediate results needed to proceed from one Step to another. Alternative datasets and models were considered in the implementation. The epistemic hazard uncertainty was quantified through an ensemble modeling technique accounting for alternative models' weights and yielding a distribution of hazard curves represented by the mean and various percentiles. Hazard curves were calculated at 2,343 Points of Interest (POI) distributed at an average spacing of ∼20 km. Precalculated probability maps for five maximum inundation heights (MIH) and hazard intensity maps for five average return periods (ARP) were produced from hazard curves. In the entire NEAM Region, MIHs of several meters are rare but not impossible. Considering a 2% probability of exceedance in 50 years (ARP≈2,475 years), the POIs with MIH >5 m are fewer than 1% and are all in the Mediterranean on Libya, Egypt, Cyprus, and Greece coasts. In the North-East Atlantic, POIs with MIH >3 m are on the coasts of Mauritania and Gulf of Cadiz. Overall, 30% of the POIs have MIH >1 m. NEAMTHM18 results and documentation are available through the TSUMAPS-NEAM project website (http://www.tsumaps-neam.eu/), featuring an interactive web mapper. Although the NEAMTHM18 cannot substitute in-depth analyses at local scales, it represents the first action to start local and more detailed hazard and risk assessments and contributes to designing evacuation maps for tsunami early warning

Investigation of Tsunami Hydrodynamic Parameters in Inundation Zones with Different Structural Layouts

In this study, we analyze the tsunami parameter "hydrodynamic demand" (HD) using advanced numerical modeling. The HD can be defined as the square of the Froude number, which represents the relative value of the drag force (damage level) of tsunami waves in the inundation zone. The other key hydrodynamic parameters investigated in this study include maximum flow depth (inundation depth), maximum current velocity and its direction, and maximum water elevation and discharge flux occurring during tsunami inundation. The analyses are performed on regular-shaped basins with various orientations and distribution of coastal and land structures in order to provide comparisons of the results in a number of different case studies. We also provide information for defining damage levels in residential areas and for testing the performance of coastal protection structures

Structural and Non-Structural Countermeasures and Awareness Studies After the Tsunami Disaster: Case of Japan

Tsunami generated by the earthquake with a magnitude of 9.0 on March, 11, 2011 caused a high number of casualties and significant economic loss. Planning and reconstruction studies following the 2011 Tsunami in Japan are important examples of countermeasures to be taken against tsunamis In this study, observations from two field surveys conducted after five years following the tsunami event, focusing on structural and non-structural countermeasures in addition to disaster management and creation of disaster awareness studies are presented in details, and current measures in Turkey are also discussed

TSUNAMİ AFETİ SONRASI YAPISAL VE SOSYAL PLANLAMA, YAPILANMA AŞAMALARI VE FARKINDALIK: JAPONYA ÖRNEĞİ

Tsunami generated by the earthquake with a magnitude of 9.0 on March, 11, 2011 caused a high number of casualties and significant economic loss. Planning and reconstruction studies following the 2011 Tsunami in Japan are important examples of countermeasures to be taken against tsunamis In this study, observations from two field surveys conducted after five years following the tsunami event, focusing on structural and non-structural countermeasures in addition to disaster management and creation of disaster awareness studies are presented in details, and current measures in Turkey are also discussed

Investigation of Hydrodynamic Parameters and the Effects of Breakwaters During the 2011 Great East Japan Tsunami in Kamaishi Bay

The March 2011 Great East Japan Tsunami was one of the most disastrous tsunami events on record, affecting the east coast of Japan to an extreme degree. Extensive currents combined with flow depths in inundation zones account for this devastating impact. Video footage taken by the eyewitnesses reveals the destructive effect and dragging capability of strong tsunami currents along the coast. This study provides a numerical modeling study in Kamaishi Bay, calculating the damage inflicted by tsunami waves on structures and coastlines in terms of the square of the Froude number Fr (2) ; and also other calculated hydrodynamic parameters, such as the distribution of instantaneous flow depths, maximum currents and water surface elevations that occurred during this catastrophic tsunami. Analyses were performed by using the tsunami numerical modeling code NAMI DANCE with nested domains at a higher resolution. The effect of the Kamaishi breakwater on the tsunami inundation distance and coastal damage was tested by using the conditions of "with breakwater," "without breakwater," and "damaged breakwater." Results show that the difference between the hydrostatic pressure on the seaward side of the breakwater and the leeward side of the breakwater is quite high, clarifying conditions contributing to failure of the breakwater. Lower water surface elevations were calculated in the case of a breakwater existing at the entrance, a partly valid condition for the damaged breakwater case. The results are different for current velocities and in the "with breakwater" condition due to the concentration of energy through the breakwater gaps

The 20th July 2017 Bodrum-Kos Tsunami Field Survey

The July 20, 2017 Bodrum-Kos Earthquake caused tsunami wave motions and damage in the south of Bodrum Peninsula, Turkey, and on Kos Island, Greece. Immediately after the earthquake, we conducted several post-tsunami field surveys including interviews in coastal zones impacted by the tsunami, i.e., the coastlines of Bodrum Peninsula, Karaada Islet and Akyaka Town in Gokova Bay, Turkey, and eastern Kos Island, Greece. We present observations and measurements to document the variation of the tsunami effects along the coast. The largest tsunami runup was about 1.9m and observed at the mouth of a small dry streambed at Gumbet Bay, Bodrum. No significant water motions were reported at the northern and western coasts of Bodrum Peninsula. The tsunami runup distribution along the coast of eastern Kos was overall regular, with runup not exceeding 1m except in the Port of Kos where a 1.5m tsunami runup was measured

The 20th July 2017 Bodrum–Kos tsunami field survey

Summarization: The July 20, 2017 Bodrum–Kos Earthquake caused tsunami wave motions and damage in the south of Bodrum Peninsula, Turkey, and on Kos Island, Greece. Immediately after the earthquake, we conducted several post-tsunami field surveys including interviews in coastal zones impacted by the tsunami, i.e., the coastlines of Bodrum Peninsula, Karaada Islet and Akyaka Town in Gökova Bay, Turkey, and eastern Kos Island, Greece. We present observations and measurements to document the variation of the tsunami effects along the coast. The largest tsunami runup was about 1.9 m and observed at the mouth of a small dry streambed at Gumbet Bay, Bodrum. No significant water motions were reported at the northern and western coasts of Bodrum Peninsula. The tsunami runup distribution along the coast of eastern Kos was overall regular, with runup not exceeding 1 m except in the Port of Kos where a 1.5 m tsunami runup was measured.Παρουσιάστηκε στο: Pure and Applied Geophysic