Explore the vast range of titles available.

January 2022 witnessed the violent eruption of Hunga Tonga–Hunga Haʻapai submarine volcano in the South Pacific. With a volcanic explosivity index possibly equivalent to VEI 5, this represents the largest seaborne eruption for nearly one and a half centuries since Indonesia’s cataclysmic explosion of Krakatau in AD 1883. The Tongan eruption remarkably produced ocean-wide tsunamis, never documented before in the Pacific instrumental record. Volcanically generated tsunamis have been referred to as a ‘blind spot’ in our understanding of tsunami hazards, particularly in the Pacific Ocean. This event therefore presents a unique opportunity for investigating the multiple processes contributing to volcanic tsunamigenesis. It is argued that, although challenges exist, integrating theoretical, observational, field and modelling techniques offers the best approach to improving volcanic tsunami hazard assessment across Oceania.

Thailand’s low-lying capital city Bangkok is a dense metropolis, one of Asia’s rapidly growing ‘megacities’, and home to over 10 million residents. Bangkok’s location on the sinking Chao Phraya Delta means it has a high susceptibility to river flooding. However, the possible contribution of marine incursion to river flooding is not as widely recognised and needs further consideration. We therefore re-examine the historically documented floods in AD 1785 and 1983. Available evidence suggests that the superposition of different flood behaviours was important during both events. Attention is drawn to the evidence for, and contributory roles played by, astronomical spring tides, meteorological tides, storm waves and possibly storm surge. These marine effects can exacerbate river floods caused by seasonal peak flows in the tidal lower Chao Phraya River during the early north-east monsoon. For future management of flood risk, it is therefore necessary to recognise that Bangkok has a compound flood-risk profile that includes both hydrometeorological and marine influences. The significance of marine influences on Bangkok’s flood risk is likely to increase in future with continuing eustatic sea-level rise and subsidence of the Chao Phraya Delta.

Modern tsunami events have highlighted the vulnerability of port structures to these high-impact but infrequent occurrences. However, port planning rarely includes adaptation measures to address tsunami hazards. The 2011 Tohoku tsunami presented us with an opportunity to characterise the vulnerability of port industries to tsunami impacts. Here, we provide a spatial assessment and photographic interpretation of freely available data sources. Approximately 5000 port structures were assessed for damage and stored in a database. Using the newly developed damage database, tsunami damage is quantified statistically for the first time, through the development of damage fragility functions for eight common port industries. In contrast to tsunami damage fragility functions produced for buildings from an existing damage database, our fragility functions showed higher prediction accuracies (up to 75 % accuracy). Pre-tsunami earthquake damage was also assessed in this study and was found to influence overall damage assessment. The damage database and fragility functions for port industries can inform structural improvements and mitigation plans for ports against future events.

Two recent tsunamis in Indonesia highlight the importance of submarine landslides. Although both events had different origins (volcanic, seismic), submarine landsliding was probably the key component in tsunamigenesis. While a few recent submarine landslide-generated tsunamis have been discussed in the literature, these types of events have not been seriously scrutinised by geoscientists or hazard modellers. This is most likely because of both a lack of awareness and also the common perception that such events are too remote a possibility to be of major concern. However, by catching us off-guard, these two Indonesian events have brought slope-failure tsunamigenesis into sharper focus. It is hoped that this will stimulate greater scholarship on the issue of slope-failure tsunamigenesis worldwide, with an aim to better understanding event characteristics, probabilities, and ultimately better inform existing risk reduction strategies.