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External surges are a key component of extreme water levels in the North Sea. Caused by low-pressure cells over the North Atlantic and amplified at the continental shelf, they can drive water-level changes of more than 1 m at the British, Dutch and German coasts. This work describes an improved and semi-automated method to detect external surges in sea surface time histories. The method is used to analyse tide gauge and meteorological records from 1995 to 2020 and to supplement an existing dataset of external surges, which is used in the determination of design heights of coastal protection facilities. Furthermore, external surges are analysed with regard to their annual and decadal variability, corresponding weather conditions, and their interaction with storm surges in the North Sea. A total of 33 % of the 101 external surges occur within close succession of each other, leading to the definition of serial external surges, in which one or more external surges follow less than 72 h after the previous external surge. These serial events tend to occur more often during wind-induced storm surges. Moreover, the co-occurrence with a storm surge increases the height of an external surge by 15 % on average, highlighting the importance of the consideration of combined events in coastal protection strategies. The improved dataset and knowledge about serial external surges extend the available basis for coastal protection in the North Sea region.

A field survey team went to Palu City, Indonesia in the aftermath of the September 28th, 2018 earthquake and tsunami to investigate its effects on local infrastructure and buildings. The study focused on the coast of Palu Bay, where a tsunami wave between approximately 2 and 7 m high impacted the local community as a result of several complex tsunami source mechanisms. The following study outlines the results, focused on loading caused by debris entrained within the inundating flow. Damage to timber buildings along the coast was widespread, though reinforced concrete structures for the most part survived, providing valuable insights into the type of debris loads and their effects on structures. The results of this survey are placed within the context of Canadian tsunami engineering challenges and are compared to the recently-released ASCE 7 Chapter 6 – Tsunami Loads and Effects, detailing potential research gaps and needs.

The September 28, 2018 earthquake and tsunami, which occurred north of Palu City, Indonesia, attracted widespread interest from the scientific community due to the unusually large tsunami ...

The September 28 2018 Palu tsunami surprised the scientific community, as neither the earthquake magnitude nor its strike-slip mechanism were deemed capable of producing the wave heights that were observed. However, recent research has shown that the earthquake generated several landslides inside Palu bay. The authors conducted a post-disaster field survey of the area affected to collect spatial data on tsunami inundation heights, nearshore and bay bathymetry, and carried out eyewitness interviews to collect testimonies of the event. In addition, numerical simulations of the tsunami generation and propagation mechanisms were carried out and validated with the inferred time series. Seven small submarine landslides were identified along the western shore of the bay, and one large one was reported on the eastern shore of Palu City. Most of these landslides occurred at river mouths and reclamation areas, where soft submarine sediments had accumulated. The numerical simulations support a scenario in which the tsunami waves that arrived at Palu city 4–10 min after the earthquake were caused by the co-seismic seafloor deformation, possibly coupled with secondary waves generated from several submarine landslides. These findings suggest that more comprehensive methodologies and tools need to be used when assessing probabilistic tsunami hazards in narrow bays.

The problem of modelling the dynamic behavior of structures under extreme hydraulic loading requires a comprehensive examination at a range of scale to develop analytical relationships in the development of scaling methodologies. The experimental program outlined here begins this process by examining the structural response of idealized wooden structures under solitary wave loading. This program will be the first comprehensive set of experiments merging structural and hydraulic modelling techniques to capture dynamic behaviour of idealized structural elements.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/tGA_77Lhc1E

Designing tsunami-safe buildings relies on engineering codes to estimate induced loads. The only such design code, written in mandatory language is "Chapter 6 - Tsunami Loads and Effects" published recently in the ASCE 7-16 (2017). In this study, for the first time, a bore originating from a solitary wave was used to investigate the damage to an idealized structure at relatively large scale (1:5). Therefore, model tests with rigid and non-rigid structures were combined to provide a unique data set of pressure distributions and structural response. This data set could be used to model structural behavior more realistically within the Froude-Cauchy similitude.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/vVnEu9YIuQw

Tsunami propagation and inundation are commonly simulated using large-scale depth-averaged models. In such models, the quadratic friction law with a selected Manning’s coefficient is generally applied to account for the effect of bottom surface roughness in each computational element. Buildings and tree vegetation in coastal areas are usually smaller than the computational element size. Using empirical Manning’s coefficients to account for such large objects is not physically sound and, particularly in tsunami inundation modelling, this may result in large uncertainties. Therefore, an improved understanding of the processes associated with the hydraulic resistance of the so-called macro-roughness elements (MRE) is required. Relevant parameters such as shape, height and arrangement of the MRE should be investigated through laboratory experiments or numerical tests using a well-validated three-dimensional CFD model. Given the correlation of such parameters to the MRE-induced hydraulic resistance, empirical formulae were developed and directly implemented as sink terms in depth-averaged numerical solvers such as non-linear shallow-water (NLSW) models.