Asteroid Impact Effects And Their Immediate Hazards For Human Populations

📝 Abstract

A set of 50,000 artificial Earth impacting asteroids was used to obtain, for the first time, information about the dominance of individual impact effects such as wind blast, overpressure shock, thermal radiation, cratering, seismic shaking, ejecta deposition and tsunami for the loss of human life during an impact event for impactor sizes between 15 to 400 m and how the dominance of impact effects changes over size. Information about the dominance of each impact effect can enable disaster managers to plan for the most relevant effects in the event of an asteroid impact. Furthermore, the analysis of average casualty numbers per impactor shows that there is a significant difference in expected loss for airburst and surface impacts and that the average impact over land is an order of magnitude more dangerous than one over water.

💡 Analysis

A set of 50,000 artificial Earth impacting asteroids was used to obtain, for the first time, information about the dominance of individual impact effects such as wind blast, overpressure shock, thermal radiation, cratering, seismic shaking, ejecta deposition and tsunami for the loss of human life during an impact event for impactor sizes between 15 to 400 m and how the dominance of impact effects changes over size. Information about the dominance of each impact effect can enable disaster managers to plan for the most relevant effects in the event of an asteroid impact. Furthermore, the analysis of average casualty numbers per impactor shows that there is a significant difference in expected loss for airburst and surface impacts and that the average impact over land is an order of magnitude more dangerous than one over water.

📄 Content

Published in Geophysical Research Letters http://onlinelibrary.wiley.com/doi/10.1002/2017GL073191/full ASTEROID IMPACT EFFECTS AND THEIR IMMEDIATE HAZARDS FOR HUMAN POPULATIONS

Authors: Clemens M. Rumpf1,*, Hugh G. Lewis1, Peter M. Atkinson2,3,4

Affiliations: 1 University of Southampton, Engineering and the Environment, Southampton, UK 2 Lancaster University, Faculty of Science and Technology , Lancaster, UK 3 University of Southampton, Geography and Environment, Southampton, UK 4 Queen’s University Belfast, School of Geography, Archaeology and Palaeoecology, Belfast, UK

*Corresponding Author. Clemens M. Rumpf (C.Rumpf@soton.ac.uk)

Key Points:  Dominance of impact effects that are generated by asteroid impacts for every impactor diameter in the range of 15-400 m.
 Average casualty count estimation for impactors in the diameter range 0-400 m.  Impactors over land are an order of magnitude more harmful than over water despite the generation of tsunamis.
ABSTRACT A set of 50,000 artificial Earth impacting asteroids was used to obtain, for the first time, information about the dominance of individual impact effects such as wind blast, overpressure shock, thermal radiation, cratering, seismic shaking, ejecta deposition and tsunami for the loss of human life during an impact event for impactor sizes between 15 to 400 m and how the dominance of impact effects changes over size. Information about the dominance of each impact effect can enable disaster managers to plan for the most relevant effects in the event of an asteroid impact. Furthermore, the analysis of average casualty numbers per impactor shows that there is a significant difference in expected loss for airburst and surface impacts and that the average impact over land is an order of magnitude more dangerous than one over water. ONE SENTENCE SUMMARY Effect dominance varies over asteroid size and aerothermal effects are most harmful while impactors over land are more dangerous than over water. 1 INTRODUCTION What are the consequences of an asteroid impact for the human population? This question is a significant driver for today’s research activities that address the threat of asteroids that collide with the Earth [Ailor et al., 2013]. Asteroid impacts produce an array of impact effects that can harm human populations. A list of seven such impact effects is recognized and described in [Hills and Goda, 1993; Collins et al., 2005]. They are: wind blast, overpressure shock, thermal radiation, cratering, seismic shaking, ejecta deposition, and tsunami. The present work quantifies the contributions of each of these effects to overall losses due to an asteroid impact of a given size in a global setting. Published in Geophysical Research Letters http://onlinelibrary.wiley.com/doi/10.1002/2017GL073191/full Considerable work is available in the literature which addresses overall casualty numbers of asteroid impacts [Stokes et al., 2003; Harris, 2008; Shapiro et al., 2010; Boslough, 2013a; Reinhardt et al., 2016]. Previous work has compared the loss of human life for impactors over land and water masses [Stokes et al., 2003; Shapiro et al., 2010] and these studies are currently being updated with an increased focus on individual impact effects [Mathias et al., 2017; Register et al., 2017]. Additional work has focused on the loss quantification of single impact effects such as tsunamis [Chesley and Ward, 2006] facilitating limited insight into the quantification of relative impact effect dominance. The focus of the present work is comparing the contribution (dominance) of the seven impact effects to overall loss and thereby providing a nuanced view of impact effect dominance. To estimate loss of human life due to an asteroid impact, the severity of each impact effect needs to be calculated based on input parameters such as impactor size, impactor density, impact speed and impact angle. A suite of analytical impact effect models is provided in [Collins et al., 2005] and it enables estimation of impact effect severity as a function of distance from the impact site (except for tsunamis). The literature provides examples for numerical codes that typically model few effects each in great detail [Boslough and Crawford, 2008; Wünnemann et al., 2010; Gisler et al., 2011; Collins et al., 2012]. However, the high impactor count simulations performed here prohibited the use of numerically intensive codes. A suitable tsunami propagation model is presented in [Rumpf et al., 2017] which utilizes ray tracing to determine affected coastlines on the global map depending on the impact location and calculates local coastal inundation based on bathymetry as well as topography data [Patterson and US National Park Service, 2015].
Here, the impact effects were propagated away from the impact location and across the local population utilizing global population data on a 2.5x2.5 grid from 2015 [CIESIN et al., 2005

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