No abstract

No abstract

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.

Abstract. 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 5,000 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 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.

No abstract

Earthquake catastrophe models combine simulated earthquake hazard intensity parameters, such as ground-shaking intensity and liquefaction potential, with spatial data layers describing the geography and vulnerability of exposed assets at risk (property, populations and infrastructure) to calculate the probability of loss. There is significant scope for applying catastrophe models to disaster relief planning, risk mitigation and financing, especially for earthquake-prone developing economies in Asia. Potential uses of earthquake catastrophe models in these areas include the following. Estimating probable levels of damage across an area resulting from a range of possible earthquake events. These estimates are useful in assessing the scale of the response required when an earthquake event actually occurs and for devising a realistic plan for the disaster response effort.Quantifying the humanitarian and economic benefit of introducing or upgrading existing risk mitigation measures in advance of their introduction; and assessing the loss potential of possible sites for future infrastructure and/or industrial facilities.Quantifying risk metrics fundamental to the pricing of financial risk transfer solutions that enable the transfer of the cost of relief and reconstruction away from the damaged national economy, thereby cushioning it from financial shock caused by major earthquake damage.

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.

These datasets are provided in courtesy of the Asian School of the Environment, Nanyang Technological University and Earth Observatory of Singapore. You may use the data freely with acknowledgement.