Publications

Devastating hot ash clouds (Pyroclastic density currents - PDCs) can run over hills and ridges crossing significant topographic obstacles. The processes that govern the interaction of PDCs with obstacles remain poorly understood leaving uncertainty in hazard planning and mitigation. Here, we report the results of large-scale experimental PDCs comprising hot volcanic particles and gas propagating across ridge-shaped obstacles.

Observations from high-speed video and measurements of the velocity, density and temperature structure of the flows are used to identify the flow processes that occur when PDCs propagate across and become partially blocked by hill-shaped topographic obstacles; and how these characteristics are recorded in PDC deposits. The facies architecture of experimental deposits across ridges resembles those of natural PDC deposits from Te Maari and Taupo¯ volcanoes (New Zealand). The findings of this study can guide the interpretation of PDC deposits or be taken into consideration in numerical models simulating the propagation of PDCs across complex topography for hazard forecast.

Infrastructure network modelling to identify elements of a system that are most vulnerable, and support risk mitigation strategies, and examine restoration plans.
Network models have been previously proposed for spatial cascades of natural hazard events. These have generally not taken time into account, with the cascade of events effectively assumed to occur instantaneously. This study introduces a dynamic, network-based stochastic model developed as a virtual testbed to simulate complex multihazard interactions between multiple temporal processes, often occurring on different time scales. 

We exemplify our methodology by investigating impacts of volcanic ashfall on river flow dynamics in the Rangitaiki and Tarawera river systems in New Zealand, simulating hydrological processes over a 365-day period with a volcanic eruption. Our results demonstrate how testbeds can be use to explore ‘‘what-if’’ cascading impacts scenarios, by providing a flexible, computationally efficient framework, offering crucial support for Disaster Risk Management (DRM) in volcanic regions.

Forecasting volcanic eruptions can be challenging due to the typically sparse and incomplete data, leading to analysis of analogue volcanoes with comparable physical properties and statistical behaviour to the target volcano. To solve the problem of missing events in geological and/or historical analogue eruption records, we propose a set of hierarchical trend renewal processes. From these a Bayesian model averaging scheme incorporates model uncertainty by combining the forecast times from each of the considered models. We apply this method to forecasting eruptions from Mt Taranaki in New Zealand, which last erupted in ∼1780 AD and has its entire eruption record preserved only in geological deposits.

Volcanic eruptions pose significant risks to regional economies by disrupting local industries and their interdependent supply chains. The cascading economic consequences of a volcanic disruption scenario in the Kawerau District of New Zealand's Bay of Plenty, a nationally significant hub for paper manufacturing, leads to impacts propagating through national and global value chains. Scenario analysis shows that targeted resilience measures, such as inventory stockpiling, can substantially mitigate these cascading losses. Network-based economic modelling provides an operational framework for assessing systemic risk and identifying leverage points for resilience investment, offering practical insights for strengthening preparedness in eruption-threatened regional economies.

The location of a volcanic vent controls an eruption’s hazards, intensities, and impact. Current kernel density estimation methods of future vent locations in volcanic fields assume that locations with more past-vents are more likely to produce future-vents. We examine an alternative hypothesis that an eruption depletes the magma source, causing holes or dips in the spatial density estimate for future vent locations. This is illustrated with the Auckland Volcanic Field, Aotearoa-New Zealand, where both magmatic and phreatomagmatic eruptions have occurred, according to the vent location, with the latter resulting in more explosive eruptions and hence hazard.