Stay-or-relocate model (STORM): An agent-based population displacement simulator applied to a multi-phase volcanic eruption scenario

Abstract

Households are central to societal functionality and may be impacted directly or indirectly by natural hazard events, resulting in the displacement of residents. Emergency management practitioners and policy decision-makers require adaptable decision support tools capable of accounting for fine-scale variations in hazard exposure, vulnerability and demographics across the emergency response and recovery periods. Responding to this critical need, we present the newly developed agent-based Stay-or-Relocate Model (STORM) demonstrated through application to a multi-phase and multi-hazard volcanic eruption scenario affecting the Taranaki Region, Aotearoa-New Zealand. STORM evaluates resident decision-making whether to remain, relocate or return home given household characteristics and changing circumstances over time. Decision components include evacuations, building damage, electricity and water outages, loss of road access, school disruption and reduced community liveability. Incorporation of an empirical relocation module quantifies the displaced residents’ selection of accommodation type, area of relocation, duration at location before return or further relocation, and accommodation payment support requirements. Modelling results indicate a peak of 32,000 individuals displaced following the first phase of volcanic activity (24.9% of the population of Taranaki Region), reducing to 16,400 (12.8%) as some residents return during a period of volcanic quiescence, and rising to a second peak of 47,000 (36.5%) following a second phase of volcanic activity. STORM is hazard agnostic and can be readily adjusted to suit the local context of application.