Spectral Characteristic Evolution: A New Algorithm for Gravitational Wave Propagation

We present a spectral algorithm for solving the full nonlinear vacuum Einstein field equations in the Bondi framework. Developed within the Spectral Einstein Code (SpEC), we demonstrate spectral characteristic evolution as a technical precursor to Cauchy Characteristic Extraction (CCE), a rigorous method for obtaining gauge-invariant gravitational waveforms from existing and future astrophysical simulations. We demonstrate the new algorithm's stability, convergence, and agreement with existing evolution methods. We explain how an innovative spectral approach enables a two orders of magnitude improvement in computational efficiency.Comment: 28 pages, 9 figure

Spectral Cauchy Characteristic Extraction of strain, news and gravitational radiation flux

We present a new approach for the Cauchy-characteristic extraction of gravitational radiation strain, news function, and the flux of the energy-momentum, supermomentum and angular momentum associated with the Bondi-Metzner-Sachs asymptotic symmetries. In Cauchy-characteristic extraction, a characteristic evolution code takes numerical data on an inner worldtube supplied by a Cauchy evolution code, and propagates it outwards to obtain the space-time metric in a neighborhood of null infinity. The metric is first determined in a scrambled form in terms of coordinates determined by the Cauchy formalism. In prior treatments, the waveform is first extracted from this metric and then transformed into an asymptotic inertial coordinate system. This procedure provides the physically proper description of the waveform and the radiated energy but it does not generalize to determine the flux of angular momentum or supermomentum. Here we formulate and implement a new approach which transforms the full metric into an asymptotic inertial frame and provides a uniform treatment of all the radiation fluxes associated with the asymptotic symmetries. Computations are performed and calibrated using the Spectral Einstein Code (SpEC).Comment: 30 pages, 17 figure

Community bushfire safety: A review of post-black Saturday research

Following the 'Black Saturday' bushfires of 7 February 2009, a number of research reports on community bushfire safety were presented to the Victorian Bushfires Royal Commission. These include reports from the CFA, OESC, Bushfire CRC and Department of Justice. These reports have different research aims and employ a range of methods and samples. Some reports investigate community safety issues during the Black Saturday bushfires, while others examine preparedness and intentions for future fires. This paper reviews these reports to identify common findings, inconsistencies and gaps relating to community safety during bushfires, and discusses the implications of methodological differences for research findings

Changing the rules of the game: mechanisms that shape responsibility-sharing from beyond Australian fire and emergency management

In this paper, we look beyond Australian fire and emergency management to compare ways that responsibility-sharing - broadly conceived - has occurred in other places and sectors where risks to community safety are faced. Responsibility-sharing occurs any time there is collective action, and formal and informal institutions provide the 'rules of the game' that prescribe how responsibility should be shared amongst the parties involved. We reviewed a broad sample of risk research literature in order to examine by what mechanisms responsibility-sharing institutions have been shaped in other places and sectors where risks to community safety are faced. Our review revealed more alternatives for shaping responsibilitysharing institutions than are widely considered by policy and decision makers in Australian fire and emergency management. It therefore raises an important question about why certain mechanisms are chosen, prioritised, overlooked or resisted in this sector. An alternative way of conceiving and pursuing shared responsibility is also discussed

Examining bushfire policy in action: Preparedness and behaviour in the 2009 Black Saturday fires

This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.An important part of reducing the risk of disaster is the preparedness of the people at risk. Australian bushfire authorities have policies and publicity about what households should do to be prepared - which include knowledge about fire risk, awareness of one's own risk, taking specific steps to reduce risk including having an emergency plan. Yet, there is sparse empirical evidence about the link between preparedness and actual behaviour in the face of a major disaster.The authors had an opportunity to examine the circumstances surrounding the 172 civilian fatalities which occurred in the 2009 Victorian 'Black Saturday' bushfires, through the examination of a detailed fatality dataset compiled by the Victorian Bushfires Royal Commission. This dataset allows detailed examination of Victorian bushfire safety policy ('Stay or go') in action on a day of extreme fire danger: from preparedness (both before and on the day of the fire) to behaviour on the day of the fire itself.This analysis presents three overarching findings. First, some aspects of 'Stay or go' appear to be supported: being well-prepared to evacuate remains the safest option in a bushfire; sheltering passively is very dangerous. Second, successful implementation of 'Stay or go' depends on a multitude of factors, which can challenge even the most capable householders. Third, events like Black Saturday challenge the 'Stay or go' approach, and indicate the need for a different approach on extreme fire danger days. We conclude by reflecting on the findings from this research in terms of the most recent changes to bushfire policy in Victoria.The project was funded by the Victorian Bushfires Royal Commission through the Bushfire Cooperative Research Centre. The Commission was involved in the project in an oversight capacity, in particular to ensure that strict confidence was maintained, and that conflicts of interest were avoided. Writing of this paper was supported through Saffron O’Neill’s ESRC Fellowship (S/K001175/1)

Post-Event Reviews for building Wildfire Resilience: The case of Tasmania, Australia

Wildfire frequency and severity is dramatically increasing. Wildfires cause loss of life and destroy human and natural assets; smoke chokes cities; large fires release significant amounts of carbon; and fires can permanently change ecosystems so they are less effective carbon sinks. Countries with a history of wildfire, such as Australia, are facing unprecedented fires that outstrip response capacity. Yet even in the worst catastrophes, scant attention is being paid to the massive potential for community-based initiatives to reduce risk and enhance resilience. The vast majority of wildfire reviews focus on suppression operations, and there is a clear need for these to be complemented with broader learning that provides holistic insights about how wildfire risk is generated, and how resilience might be increased. This presentation will report on the findings from one such comprehensive and holistic review of a wildfire disaster in southwest Tasmania, Australia, in January 2019. The event resulted in a locally unprecedented human and animal evacuation, and burnt through large swathes of precious wilderness world heritage area. Utilising the Post-Event Review Capability (PERC) methodology, this study investigated the causes, successes and failures of this disaster. This presentation will present findings and recommendations that are locally actionable yet provide a number of generalised lessons pertinent across multiple risk contexts. Findings demonstrate the significance of community-based actions for wildfire risk management

A review of operations research methods applicable to wildfire management

Across the globe, wildfire-related destruction appears to be worsening despite increased fire suppression expenditure. At the same time, wildfire management is becoming increasingly complicated owing to factors such as an expanding wildland-urban interface, interagency resource sharing and the recognition of the beneficial effects of fire on ecosystems. Operations research is the use of analytical techniques such as mathematical modelling to analyse interactions between people, resources and the environment to aid decision-making in complex systems. Fire managers operate in a highly challenging decision environment characterised by complexity, multiple conflicting objectives and uncertainty. We assert that some of these difficulties can be resolved with the use of operations research methods. We present a range of operations research methods and discuss their applicability to wildfire management with illustrative examples drawn from the wildfire and disaster operations research literature

After 'Black Saturday': adapting to bushfires in a changing climate

Abstract not availabl