Towards the new Thematic Core Service Tsunami within the EPOS Research Infrastructure

Tsunamis constitute a significant hazard for European coastal populations, and the impact of tsunami events worldwide can extend well beyond the coastal regions directly affected. Understanding the complex mechanisms of tsunami generation, propagation, and inundation, as well as managing the tsunami risk, requires multidisciplinary research and infrastructures that cross national boundaries. Recent decades have seen both great advances in tsunami science and consolidation of the European tsunami research community. A recurring theme has been the need for a sustainable platform for coordinated tsunami community activities and a hub for tsunami services. Following about three years of preparation, in July 2021, the European tsunami community attained the status of Candidate Thematic Core Service (cTCS) within the European Plate Observing System (EPOS) Research Infrastructure. Within a transition period of three years, the Tsunami candidate TCS is anticipated to develop into a fully operational EPOS TCS. We here outline the path taken to reach this point, and the envisaged form of the future EPOS TCS Tsunami. Our cTCS is planned to be organised within four thematic pillars: (1) Support to Tsunami Service Providers, (2) Tsunami Data, (3) Numerical Models, and (4) Hazard and Risk Products. We outline how identified needs in tsunami science and tsunami risk mitigation will be addressed within this structure and how participation within EPOS will become an integration point for community development

Towards the new Thematic Core Service Tsunami within the EPOS Research Infrastructure

Tsunamis constitute a significant hazard for European coastal populations, and the impact of tsunami events worldwide can extend well beyond the coastal regions directly affected. Understanding the complex mechanisms of tsunami generation, propagation, and inundation, as well as managing the tsunami risk, requires multidisciplinary research and infrastructures that cross national boundaries. Recent decades have seen both great advances in tsunami science and consolidation of the European tsunami research community. A recurring theme has been the need for a sustainable platform for coordinated tsunami community activities and a hub for tsunami services. Following about three years of preparation, in July 2021, the European tsunami community attained the status of Candidate Thematic Core Service (cTCS) within the European Plate Observing System (EPOS) Research Infrastructure. Within a transition period of three years, the Tsunami candidate TCS is anticipated to develop into a fully operational EPOS TCS. We here outline the path taken to reach this point, and the envisaged form of the future EPOS TCS Tsunami. Our cTCS is planned to be organised within four thematic pillars: (1) Support to Tsunami Service Providers, (2) Tsunami Data, (3) Numerical Models, and (4) Hazard and Risk Products. We outline how identified needs in tsunami science and tsunami risk mitigation will be addressed within this structure and how participation within EPOS will become an integration point for community development.publishedVersio

Towards the new Thematic Core Service Tsunami within the EPOS Research Infrastructure

publishedVersio

Case study of small harbor excitation under storm and tsunami conditions

Simultaneous nearshore and interior-to-ports wave and current measurements for small ports are not common, and few, if any, benchmarking cases at sufficient resolution exist to help validate numerical model of intermediate waves, or even long waves. The wave conditions inside the old Venetian harbor of Chania, Greece and offshore were measured and studied from 2012 to 2015. The construction of this harbor began in the 14th century, and since then, its layout has been modified to adapt to different social and to economic conditions. It is divided into a western and an eastern basin. The eastern basin is used by recreational vessels and fishing boats throughout the year. The western basin has an exposed entrance to the north, and it is essentially functional half of the year, because of the severe overtopping and flooding that occur during the northern winter storms. Our work is motivated by the necessity to protect the monument from severe winter storm conditions and allow safe mooring and all other recreational activities that take place in the exposed western basin. Two earlier studies had proposed the construction of a low crested breakwater near the harbor entrance. The first design has been partially constructed, while the second never materialized. The main disadvantage of both studies was the lack of any wave field measurements. At the same time, second order or complimentary phenomena such as harbor resonance had not been considered. To address the lack of field data, the offshore wave climate has been monitored since October 2012 using an AWAC 600kHz instrument, deployed at 23m depth. The response of the western and eastern basins of the harbor was measured with a TWR-2050 (deployed at 5.5m depth) and an RBRDuet T.D./wave (deployed at 2m depth) pressure gauges respectively. Significant wave heights ranging up to 5.8 m with significant periods of up to 10 sec were measured. The harbor pressure gauges are now being re-deployed in other locations to collect enough information to infer the resonant modes of the basins excited during storm conditions. The deployment position of the pressure gauges is based on numerical modeling results. We have employed the fully nonlinear Boussinesq module of COULWAVE using a high resolution (2m cell size) relief model and an idealized TMA directional wave spectrum. The wave field and low frequency energy distribution in the basin are captured by both numerical modeling and field measurements. The field measurements agree well with the numerical modeling analysis, providing insight as to the causes of severe disturbance and useful information that should be considered for an effective solution to the protection of the harbor. Our measurements appear the first ever nearshore measurements of waves and currents for a 2+ year period duration in Greece. The work is also being used for validation tsunami inundation models for civil defense applications in Crete

Coastal Flood Modeling Challenges in Defended Urban Backshores

Coastal flooding is a significant and increasing hazard. There are multiple drivers including rising coastal water levels, more intense hydrologic inputs, shoaling groundwater and urbanization. Accurate coastal flood event prediction poses numerous challenges: representing boundary conditions, depicting terrain and hydraulic infrastructure, integrating spatially and temporally variable overtopping flows, routing overland flows and incorporating hydrologic signals. Tremendous advances in geospatial data quality, numerical modeling and overtopping estimation have significantly improved flood prediction; however, risk assessments do not typically consider the co-occurrence of multiple flooding pathways. Compound flooding refers to the combined effects of marine and hydrologic processes. Alternatively, multiple flooding source⁻receptor pathways (e.g., groundwater⁻surface water, overtopping⁻overflow, surface⁻sewer flow) may simultaneously amplify coastal hazard and vulnerability. Currently, there is no integrated framework considering compound and multi-pathway flooding processes in a unified approach. State-of-the-art urban coastal flood modeling methods and research directions critical to developing an integrated framework for explicitly resolving multiple flooding pathways are presented

Wave overtopping due to harbour resonance

Summarization: Harbour resonance and its contribution to wave overtopping are examined for a small irregular-shaped harbour in the eastern Mediterranean. Offshore wave measurements are used to determine the incident wave conditions during storm events. Resonant periods of the harbour basin are identified through in situ measurements at four different deployment locations during multiple storm events. Numerical simulations using a Boussinesq-type model and an idealised offshore spectrum yielded similar resonant frequencies to the field measurements and allowed us to visualise the corresponding resonant modes. Wave overtopping along the vertical docks of the harbour is inferred by combining numerical time series of free surface elevation with EurOtop formulae. Two approaches to estimate wave overtopping rates are examined and compared: a novel approach considering wave energy in the sea-swell frequency range and varying the freeboard through time series in the infragravity frequency range, and the conventional method that considers spectral parameters along the entire frequency range. The novel approach provides an estimate for the contribution of harbour resonance to wave overtopping considering that infragravity wave energy inside the basin is mainly resonance-driven.Presented on: Coastal Engineerin

Tsunami simulations for regional sources in the south China and adjoining seas

Summarization: We present 14 scenarios of potential tsunamis in the South China Sea and its adjoining basins, the Sulu and Sulawezi Seas. The sources consist of earthquake dislocations inspired by the the study of historical events, either recorded (since 1900) or described in historical documents going back to 1604. We consider worst-case scenarios, where the size of the earthquake is not limited by the largest known event, but merely by the dimension of the basin over which a coherent fault may propagate. While such scenarios are arguably improbable, they may not be impossible, and as such must be examined. For each scenario, we present a simulation of the tsunami’s propagation in the marine basin, exclusive of its interaction with the coastline. Our results show that the South China, Sulu and Sulawezi Seas make up three largely independent basins where tsunamis generated in one basin do not leak into another. Similarly, the Sunda arc provides an efficient barrier to tsunamis originating in the Indian Ocean. Furthermore, the shallow continental shelves in the Java Sea, the Gulf of Thailand and the western part of the South China Sea significantly dampen the amplitude of the waves. The eastern shores of the Malay Peninsula are threatened only by the greatest—and most improbable—of our sources, a mega-earthquake rupturing all of the Luzon Trench. We also consider two models of underwater landslides (which can be triggered by smaller events, even in an intraplate setting). These sources, for which there is both historical and geological evidence, could pose a significant threat to all shorelines in the region, including the Malay Peninsula.Presented on