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Airport
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Surface transportation site consisting of airfield and facilities used to service aircraft.
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Surface and near-surface (< 10 m above ground) environmental conditions at airfields are considered when referring to airports.
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Exposure
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People, property, systems, or other elements present in hazard zones that are thereby subject to potential losses.
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UNISDR 2009, Craig et al. 2016b
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Fragility function
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Probabilistic vulnerability models that describe the probability that a damage or functional state will be reached or exceeded for a given hazard intensity.
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Only fragility functions for volcanic ash are discussed in detail.
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Singhal and Kiremidjian 1996, Choi et al. 2004, Rossetto et al. 2013, Tarbotton et al. 2015
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Hazard
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A phenomenon that may cause loss of life, injury or other health impacts, property damage, loss of livelihoods and services, social and economic disruption, or environmental damage.
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Hazard is referred to in the context of a dangerous phenomenon from volcanoes (i.e. volcanic tephra, pyroclastic density currents, lava flows, lahars).
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UNISDR 2009
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Hazard Intensity Metric (HIM)
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A measure used to describe the intensity of a volcanic hazard at a particular site, which is the independent variable of vulnerability and fragility functions.
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Ash thickness is often used as the HIM for volcanic ash fragility functions. Alternative HIMs are explored here including ash-settling rate and particle size.
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Wilson 2015, Wilson et al. 2017
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Impact
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The effect a hazardous event has on an exposed system. Defined as a function of the hazard, and the vulnerability and exposure of a system (I = H*V*E).
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Multiple impact types are inferred when discussing impact.
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Jenkins et al. 2014b, Craig et al. 2016b
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Impact State (IS)
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States of damage or disruption defined by qualitative impact descriptions.
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These are numbered numerically with 0 being “no damage or disruption”, and increasing numbers referring to an increasing level of damage or disruption.
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Blong 2003, Wilson et al. 2017
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Impact type
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An individual feature of an infrastructure system that can be affected by the function of hazard, vulnerability and exposure.
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Surface transportation impact types include skid resistance reduction, visibility impairment, road marking coverage and engine air inlet filter blockage.
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Maritime
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Surface transportation connected with the sea.
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Covers trade shipping, recreational boating and ferry services.
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Mitigation
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The lessening or limitation of the adverse impacts of hazards and related disasters.
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UNISDR 2009
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Rail
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Surface transportation on wheeled vehicles running on rails.
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Covers electric and diesel modes on conventional tracks.
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Risk
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The combination of the probability of an event and its negative consequences.
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A volcanic hazard is implied to be the “event”.
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UNISDR 2009
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Road
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Surface transportation on dedicated sealed or unsealed routes.
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We generally refer to paved surfaces, particularly asphalt concrete.
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Skid resistance
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The force developed when a tyre that is prevented from rotating slides along apavement surface.
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(Often referred to as traction in post-eruption literature.)
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Highway research board 1972, Blake et al. 2017a
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Surface transportation
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Transportation types on land or water used to convey passengers and/or goods.
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Road, rail and maritime transport are covered, as well as transport that occurs on the ground at airports.
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Visual range
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The longest distance that a large, black object can be seen against the sky at the horizon with the unaided eye.
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Used as a measure of visibility.
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Hyslop 2009, Binkowski et al. 2002, Blake 2016
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Vulnerability
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The characteristics and circumstances of a community, system or asset that make it susceptible to the damaging effects of a hazard.
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Largely transportation systems or assets are referred to.
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UNISDR 2009
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Vulnerability function
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A correlation of hazard intensity to a component’s damage or function loss as a value relative to total impact or as an economic cost.
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We generally refer to fragility functions instead, which incorporate probability.
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Wilson 2015
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