Susanna F Jenkins

Regional ash fall hazard I: A probabilistic assessment methodology

Volcanic ash is one of the farthest-reaching volcanic hazards and ash produced by large magnitude explosive eruptions has the potential to affect communities over thousands of kilometres. Quantifying the hazard from ash fall is problematic, in part because of data limitations that make eruption characteristics uncertain but also because, given an eruption, the distribution of ash is then controlled by time and altitude-varying wind conditions. Any one location may potentially be affected by ash falls from one, or a number of, volcanoes so that volcano-specific studies may not fully capture the ash fall hazard for communities in volcanically active areas. In an attempt to deal with these uncertainties, this paper outlines a probabilistic framework for assessing ash fall hazard on a regional scale. The methodology employs stochastic simulation techniques and is based upon generic principles that could be applied to any area, but is here applied to the Asia-Pacific region. Average recurrence intervals for eruptions greater than or equal to Volcanic Explosivity Index 4 were established for 190 volcanoes in the region, based upon the eruption history of each volcano and, where data were lacking, the averaged eruptive behaviour of global analogous volcanoes. Eruption histories are drawn from the Smithsonian Institution’s Global Volcanism Program catalogue of Holocene events and unpublished data, with global analogues taken from volcanoes of the same type category: Caldera, Large Cone, Shield, Lava dome or Small Cone. Simulated are 190,000 plausible eruption scenarios, with ash dispersal for each determined using an advection–diffusion model and local wind conditions. Key uncertainties are described by probability distributions. Modelled results include the annual probability of exceeding given ash thicknesses, summed over all eruption scenarios and volcanoes. A companion paper describes the results obtained for the Asia-Pacific region

A Global Earthquake Building Damage and Casualty Database

This chapter presents a preliminary overview of the Cambridge University Earthquake Damage Database (CUEDD) now the Cambridge Earthquake Impact Database (CEQID) with emphasis on its human casualty component. CUEDD is based on earthquake damage data assembled by the Martin Centre at Cambridge University since 1980, complemented by other more-recently published and some unpublished data. The database through its organised, expandable and web-accessible format, summarizes information on worldwide post-earthquake building damage surveys which have been carried out since the 1960s (www.ceqid.org). Currently it contains data on the performance of more than 1.3 million individual buildings, in 600 surveys following 50 separate earthquakes. The database provides total recorded casualties (deaths, seriously and moderately injured), and casualty rates as a proportion of population with definitions of injury levels used, and information on dominant types of injury, age groups affected, etc. It also provides geographically disaggregated data where possible, and associates them with tables and GIS maps. Sources of information on other aspects of human casualty information (epidemiological studies, health care impacts, etc.) are provided. Analytical tools enable relationships between casualty rates, building classes and ground motion parameters to be determined.

Human survival in volcanic eruptions: Thermal injuries in pyroclastic surges, their causes, prognosis and emergency management

This study of burns patients from two eruptions of Merapi volcano, Java, in 1994 and 2010, is the first detailed analysis to be reported of thermal injuries in a large series of hospitalised victims of pyroclastic surges, one of the most devastating phenomena in explosive eruptions. Emergency planners in volcanic crises in populated areas have to integrate the health sector into disaster management and be aware of the nature of the surge impacts and the types of burns victims to be expected in a worst scenario, potentially in numbers and in severity that would overwhelm normal treatment facilities. In our series, 106 patients from the two eruptions were treated in the same major hospital in Yogyakarta and a third of these survived. Seventy-eight per cent were admitted with over 40% TBSA (total body surface area) burns and around 80% of patients were suspected of having at least some degree of inhalation injury as well. Thirty five patients suffered over 80% TBSA burns and only one of these survived. Crucially, 45% of patients were in the 40-79% TBSA range, with most suspected of suffering from inhalation injury, for whom survival was most dependent on the hospital treatment they received. After reviewing the evidence from recent major eruptions and outlining the thermal hazards of surges, we relate the type and severity of the injuries of these patients to the temperatures and dynamics of the pyroclastic surges, as derived from the environmental impacts and associated eruption processes evaluated in our field surveys and interviews conducted by our multi-disciplinary team. Effective warnings, adequate evacuation measures, and political will are all essential in volcanic crises in populated areas to prevent future catastrophes on this scale.

Global Volcanic Hazards and Risk: Volcanic ash fall impacts

All explosive eruptions produce volcanic ash (fragments of volcanic rock < 2mm: Figure 12.1), which is then dispersed by prevailing winds and deposited as ash falls hundreds or even thousands of kilometres away. Volcanic ash suspended in the atmosphere is well known as a hazard for aviation, as was demonstrated during the 2010 eruption of Eyjafjallajökull, Iceland, which led to substantial disruption to flights in Europe and an estimated US

Impacts from volcanic ash fall

5 billion loss as global businesses and supply chains were affected (Ragona et al., 2011). Volcanic ash fall can also create considerable impacts on the ground. As a general rule, impacts will be more severe with increasing thickness of ash fall. Relatively thin falls (< 10 mm) may have adverse health effects for vulnerable individuals and can disrupt critical infrastructure services, aviation, agriculture and other socio-economic activities over potentially very large areas. Thick ash falls (>100 mm) may damage crops, vegetation and infrastructure, cause structural damage to buildings and create major clean-up requirements. However, they are typically confined to within tens of kilometres of the vent and, as they occur with large eruptions, are relatively rare.

Development of a new global Volcanic Hazard Index (VHI)

Abstract All explosive eruptions produce volcanic ash, fragments of volcanic rock generated when magma or vent material is explosively disintegrated during eruption. Volcanic ash is convected upwards within the eruption column and carried downwind, falling out of suspension and potentially affecting communities across hundreds of square kilometers. Although ash falls rarely endanger human life directly, threats to public health and disruption to critical infrastructure services, aviation, and primary production (e.g. agriculture) can lead to significant societal impacts. Even relatively small eruptions such as the Eyjafjallajokull eruption in Iceland in 2010 (Volcanic Explosivity Index of 4) can cause widespread disruption, damage, and economic loss. Knowledge of the likely impacts can support mitigation actions, crisis planning, and emergency management activities. This chapter presents an overview of ash fall impacts for sectors of society including buildings, critical infrastructure, and agriculture; and discuss associated socioeconomic factors. We also discuss the likely response (vulnerability) of these key sectors to ash fall impacts. Broad relationships between volcanic ash thickness and levels of damage and disruption have been outlined. Understanding these vulnerabilities is an essential step towards building resilience for communities.

Estimating building vulnerability to volcanic ash fall for insurance and other purposes

Background Globally, more than 800 million people live in areas that have the potential to be affected by volcanic hazards, and this number is growing [Chapter 4]. The need for informed judgements regarding the global extent of potential volcanic hazards and the relative threats is therefore more pressing than ever. There is also an imperative to identify areas of relatively high hazard where studies and risk reduction measures may be best focussed. Various authors have tackled this task at a range of spatial scales, using a variety of techniques. At some well-studied volcanoes, the geological record has been used in combination with numerical modelling to create probabilistic hazard maps of volcanic flows and tephra fall [Chapter 6 and 20]. Such sources of information can be hugely beneficial in land use planning during times of quiescence and in emergency planning during times of unrest. Unfortunately, creating high-resolution probabilistic hazard maps for all volcanoes is not yet feasible. There is therefore a need for a methodology for volcanic hazard assessment that can be applied universally and consistently, which is less data-and computing-intensive. The aim of such an approach is to identify, on some objective overall basis, those volcanoes that pose the greatest danger, in order that more indepth investigations and disaster risk reduction efforts can then be focused on them. Previous methods An index-based approach to volcanic hazard assessment involves assigning scores to a series of indicators, which are then combined to give an overall hazard score. Indicators typically include measures of the frequency of eruptions, the relative occurrence of different kinds of eruptions and their related hazards, the footprints of these hazards, and eruption size. Indices are well suited to the problem of volcanic hazard assessment, as they allow the decomposition of the complex system into a suite of volcanic system controls and simple quantitative variables and factors that jointly characterise threat potential. Ewert (2007) presented an index-based methodology for assessing volcanic threat (the combination of hazard and exposure) in the USA, to permit prioritisation of research, monitoring and mitigation.

Damage from lava flows: insights from the 2014–2015 eruption of Fogo, Cape Verde

Volcanic ash falls are one of the most widespread and frequent volcanic hazards, and are produced by all explosive volcanic eruptions. Ash falls are arguably the most disruptive volcanic hazard because of their ability to affect large areas and to impact a wide range of assets, even at relatively small thicknesses. From an insurance perspective, the most valuable insured assets are buildings. Ash fall vulnerability curves or functions, which relate the magnitude of ash fall to likely damage, are the most developed for buildings, although there have been important recent advances for agriculture and infrastructure. In this paper, we focus on existing vulnerability functions developed for volcanic ash fall impact on buildings, and apply them to a hypothetical building portfolio impacted by a modern-day Tambora 1815 eruption scenario. We compare and contrast the different developed functions and discuss some of the issues surrounding estimation of potential building damage following a volcanic eruption. We found substantial variability in the different vulnerability estimates, which contribute to large uncertainties when estimating potential building damage and loss. Given the lack of detailed and published studies of building damage resulting from ash fall this is not surprising, although it also appears to be the case for other natural hazards for which there are far more empirical damage data. Notwithstanding the potential limitations of some empirical data in constraining vulnerability functions, efforts are required to improve our estimates of building damage under ash fall loading through the collection of damage data, experimental testing and perhaps theoretical failure analysis. For insurance purposes, the current building typologies provided for use with vulnerability functions are too detailed to map to the relatively limited information on building types that is typically available to insurers. Thus, efforts to provide vulnerability functions that can be used where only limited information is available regarding building types would also be valuable, both for insurers and for at-risk areas that have not been subject to detailed building vulnerability surveys.

Challenges of Volcanic Crises on Small Islands States

Fast-moving lava flows during the 2014–2015 eruption of Fogo volcano in Cape Verde engulfed 75% (n = 260) of buildings within three villages in the Chã das Caldeiras area, as well as 25% of cultivable agricultural land, water storage facilities and the only road into the area. The eruption had a catastrophic impact for the close-knit communities of Chã, destroying much of their property, land and livelihoods. Volcanic risk assessment typically assumes that any object - be it a building, infrastructure or agriculture - in the path of a lava flow will be completely destroyed. Vulnerability or fragility functions for areas impacted by lava flows are thus binary: no damage in the absence of lava and complete destruction in the presence of lava. A pre-eruption field assessment of the vulnerability of buildings, infrastructure and agriculture on Fogo to the range of volcanic hazards was carried out in 2010. Many of the areas assessed were subsequently impacted by the 2014–2015 eruption and, shortly after the eruption ended, we carried out a post-eruption field assessment of the damage caused by the lava flows. In this paper, we present our findings from the damage assessment in the context of building and infrastructural vulnerability to lava flows. We found that a binary vulnerability function for lava flow impact was appropriate for most combinations of lava flow hazard and asset characteristics but that building and infrastructure type, and the flow thickness, affected the level of impact. Drawing on these observations, we have considered potential strategies for reducing physical vulnerability to lava flow impact, with a focus on buildings housing critical infrastructure. Damage assessments for lava flows are rare, and the findings and analysis presented here are important for understanding future hazard and reconstruction on Fogo and elsewhere.

Global Volcanic Hazards and Risk: Global distribution of volcanic threat

Island communities frequently display specific risk-related characteristics that are attributable to the island locations of volcano-affected communities, in terms of exposure, vulnerability and living with the volcanic risk. This chapter examines volcanic crisis response and communication in island communities. We analyse lessons from volcanic crises in 1976 at La Soufriere (Guadeloupe, France), in 2005 and 2006 at Karthala (Grande Comore, Comoros), and in 1995 at Fogo (Cape Verde). Our analysis underscores the strong influence of deep-seated causes (historical, political, cultural, social, economic, and environmental) on the success and failure of volcanic risk communication, all of which are affected by island characteristics. The case studies demonstrate the intensity of politics that manifests in these instances—perhaps because of, rather than despite, the smallness and tightness of the communities, amongst other island characteristics. Consequently, improved information and less uncertainty would not straightforwardly lead to better communication or more harmonious acceptance of decision-making processes and of decisions. One fundamental point is the need to engage with—not just consult—local populations regarding risk communication and decision-making, tailoring messages to the various audiences, and being clear regarding what is known and not known, plus what is feasible to do to fill in knowledge gaps to support decisions. Ultimately, it is necessary to foster synergies with communities to ensure that no party or knowledge dominates, but instead information is exchanged leading to decisions and decision-making processes that are better understood and accepted by all who are involved. Living with volcanic risk thus means working with communities on their terms.