Sri Lanka was the second most affected country after Indonesia, in the 2004 Boxing Day Indian Ocean tsunami (IOT). A study mission was therefore carried out twenty years after the 2004 IOT to assess the recovery of the affected regions, especially in the Eastern region of Sri Lanka, focusing on two of the most affected municipalities, i.e. Kalmunai and Batticaloa. The social and infrastructure characteristics of resettlements/relocations/new settlements in the affected regions, presence of critical infrastructure, preparedness and early warning systems installed have been assessed. It was observed that similar approaches have been adopted to plan the community relocation in both of these municipalities, while the significant reemergence of residential and commercial developments in the coastal stretches of Kalmunai municipality have been noted. Exposure analyses have revealed that there are still some critical infrastructure situated in the tsunami hazard zones. It can be construed that these municipalities have recovered from the physical losses incurred, and spatial planning is in place for future developments considering the tsunami risk. Challenges and opportunities from their differing geographical contexts appear to have been judiciously handled. However, shortcomings are noted in actual implementation due to various reasons, such as limited resources, availability of funding and preference of communities to live close to their original lands. Improving the resilience of infrastructure by designing against the expected tsunami hazard and multi-hazards, regular verification of the early warning systems and evacuation procedures are emphasized to mitigate the impacts from future tsunami.

Subduction megathrust events dominate seismicity in Chile, leading to a less comprehensive understanding of the hazard posed by crustal faults. One such source is the San Ramón fault (SRF), a potentially active fault at the eastern border of the Metropolitan Region of Santiago. This study assesses the seismic performance of three modern hospitals seismically isolated with high damping rubber bearings, located 7–24 km from the SRF trace. Their responses were evaluated using nonlinear 3D finite element models subjected to a suite of 432 synthetic ground motions. To account for the uncertainty in the seismogenic capacity of the SRF, these physics-based simulations systematically vary key source parameters, including event magnitude, average rupture velocity, and corner frequency. For facilities near the fault, the results show critical performance failures. Isolation systems are prone to pounding as displacements exceed their design limits, while large vertical accelerations cause a high probability of tensile forces in the bearings. Furthermore, interstory drifts and floor accelerations in the superstructures exceed the thresholds required to maintain continuous operation. These findings reveal that even the new generation of seismically isolated hospitals is critically vulnerable to near-fault crustal earthquakes if not explicitly designed for them. This unaccounted-for seismic hazard highlights an urgent need for comprehensive risk re-assessment and the development of targeted mitigation strategies in Santiago and other cities facing similar hazards.

During inundation, tsunami-induced scour is a major threat to the stability of onshore coastal structures. Nevertheless, the majority of current experimental research concentrate on single structures orientated perpendicular to the flow propagation, while in the real environment, coastal structures often arranged in sheltered and rotated configurations against the incident waves. This study delineates large-scale experimental research analysing tsunami-induced scour around onshore rectangular and square structures under two different setups: (i) two structures positioned in a sheltered arrangement, and (ii) single structures orientated at a 45°angle to the incoming flow. Three representative long waves with periods of 20 s, 49 s, and 147 s are generated in the HR Wallingford Fast Flow Facility using a pneumatic tsunami generator. Overhead video observations and GoPro camera are employed to analyse the maximum scour depth, spatial development of scour, and flow-structure interaction. The results show that the upstream structure modifies the flow and sediment transport processes around the downstream structure, generally reducing scour development at the rear structure through wake sheltering. The magnitude of this reduction depends on tsunami-wave period, inundation duration, and structural geometry. In contrast, structural rotation changes the flow–structure interaction by directing the incoming flow towards an exposed corner and along the adjacent faces, promoting localised scour near the corners and enhancing lateral base vortex activity. Rotated structures generally produced greater scour than the corresponding non-rotated cases, although the degree of increase varied with wave period and geometry. These findings demonstrate that structural arrangement and orientation can significantly influence the magnitude, location, and temporal development of tsunami-induced scour. The study provides new experimental evidence for improving tsunami scour hazard assessment, resilient coastal layout design, and numerical model validation for non-isolated and obliquely aligned coastal structures.

The hydrodynamic transition of tsunami waves from offshore propagation to overland inundation remains poorly resolved owing to limited high-resolution measurements of velocity and flow depth within the nearshore region. This study presents large-scale laboratory experiments investigating the hydrodynamic processes governing tsunami waveform evolution from offshore propagation through the nearshore and into overland flow. Froude-scaled tsunami waves were generated using pneumatic tsunami generators in two flume geometries at HR Wallingford: a long run-up slope representing an idealised infinite beach and a short sump geometry representing abrupt topographic transitions such as overtopped seawalls or inland depressions. Results suggest the presence of a distinct hydrodynamic transition during tsunami inundation, characterised by nonlinear offshore waveform evolution, rapid attenuation of momentum flux within the shallow nearshore region, and systematic changes in the phase relationship between flow depth and velocity. Tsunami-length waves exhibit evidence of nonlinear amplitude growth during offshore propagation despite nominally constant-depth conditions, indicating that offshore scalar elevation records alone may not fully represent the incident conditions governing subsequent inundation. In the shallow nearshore region, momentum flux decreases rapidly, suggesting a friction-dominated transition prior to shoreline impingement. Offshore, peak velocity generally precedes maximum wave amplitude, whereas the timing of these maxima progressively converges toward the shoreline. Under the tested long-wave conditions, measured near-bed shoreline velocities remained generally subcritical, suggesting that simplified critical-flow assumptions adopted in some engineering loading approaches (e.g., ASCE 7-22 load cases 2 and 3) may not fully represent all inundation regimes. Abrupt onshore topographic transitions further modify inundation behaviour through localised energy losses, suggesting that simplified gradually varied flow formulations may under-represent loading in such regions. Collectively, these findings suggest that the nearshore region acts as a friction-dominated hydrodynamic transition zone that fundamentally modifies tsunami inundation processes. Explicitly resolving this transition may improve definition of shoreline hydrodynamic loading conditions and reduce uncertainty in tsunami load estimation and coastal infrastructure design.

Tall reinforced concrete shear wall buildings used for residential purposes performed well in the 2010 Maule earthquake in Chile. Despite their good performance, in 2011 the regulations governing their design (Ministerio de Vivienda y Urbanismo 2011a, b) were changed to incorporate measures to reduce wall damage by requiring special boundary elements, along with extending the design spectrum to accommodate a broader range of soil types, among other improvements. Therefore, it is now crucial to analyse the performance of RC shear wall residential buildings designed according to the updated Chilean earthquake-resistant design standards and characterise their seismic behaviour in terms of fragility functions. However, different modelling approaches can be adopted for seismic assessment, each involving specific assumptions that significantly influence the building response. This research aims to derive the fragility of typical RC tall shear wall residential buildings in Chile located in a high seismic hazard zone, by analysing the influence of modelling assumptions on the structural response, particularly for the floor system and damping ratio, as these factors have been shown to significantly affect seismic performance. One hundred synthetic ground motion records are used to assess the seismic performance of two representative case study structures (of 9 and 17 storeys) using non-linear time history analyses. Slight, extensive, and complete damage states are selected, and fragility curves are then derived, revealing that models utilizing shell elements to represent the floor system are more efficient and better aligned with the observed behaviour of residential buildings in Chile compared to those using elastic beam elements with rigid diaphragm constraints. Moreover, it is demonstrated that damping ratios are a highly sensitive parameter, significantly influencing the collapse probability of buildings. Therefore, the use of damping ratios from studies that better reflect real-world conditions is recommended. Overall, the results show that the studied buildings do not present a risk of collapse for spectral ordinates less than or equal to 0·5 g.

There is still a gap between the structural and nonstructural components in the analysis and design stages of healthcare facilities, and as a result, earthquake-induced nonstructural damage is still causing loss of functionality despite minor structural damage. Aiming to bridge this gap, the present research focuses on the development of probabilistic damage scenarios for hospital critical rooms, taking into account the structural, nonstructural, and content interactions simultaneously. To achieve this goal, a fully equipped emergency room, intensive care unit, and operating room are simulated on the first, fourth, and fifth floors of a mid-rise hospital building and subjected to the service, design, and maximum considered earthquake levels under conventional and base-isolated support conditions. The building's floor responses are then used as input motions to assess the performance and develop fragility curves for different nonstructural elements, systems, and contents located in each critical room. Finally, probabilistic damage scenarios are developed by coupling structural, nonstructural, and content fragility curves using the performance-based earthquake engineering methodology. Results showcase the benefits of base isolation not only in reducing damage but also in ensuring high levels of functionality for all earthquake hazard levels. Conversely, functionality loss is expected in conventional hospitals during low-intensity earthquake motions due to the considerable damage to medical equipment. Moreover, it was demonstrated that solely preventing structural damage is not enough to ensure hospital functionality. Finally, it is of paramount importance to develop code-based performance objectives and expectations for nonstructural components and medical equipment under low- and design-level earthquake motions.

Currently, construction codes and standards require nonstructural fragility information to define nonstructural performance objectives and expectations for low- and design-intensity earthquake motions. To address this knowledge gap, this study focuses on the development of analytical fragility curves for unanchored medical equipment commonly found in hospital critical rooms, taking into account the building’s performance, damage progression, and content interaction simultaneously. To achieve this goal, a fully equipped emergency room, intensive care unit, and operating room are simulated on the first, fourth, and fifth floors of a mid-rise hospital building, respectively, and subjected to service, design, and maximum considered earthquake levels under fixed-to-the-base (FB) and base-isolated (BI) support conditions. The building’s floor acceleration responses are used as input motions to assess the performance of several pieces of medical equipment using rolling and sliding nonlinear models. This study has included a comprehensive uncertainty analysis to propagate different sources of uncertainty into the fragility curves. Fragility results indicate that, under FB support conditions, equipment malfunctions and failures are expected to occur during low-intensity earthquake motions, even if the hospital building experiences minor structural damage. Furthermore, knowing the damaged condition of medical equipment (malfunction/failure) is crucial for determining its availability and subsequent use to stabilize critical condition patients or save their lives. Finally, these fragility curves can be used to plan post-disaster recovery and make risk-informed decisions in healthcare facilities.