Long-term volcanic hazard assessment on El Hierro (Canary Islands)

L Becerril,R Sobradelo,J Martí,S Bartolini,J M Morales,I Galindo

doi:10.5194/nhess-14-1853-2014

Abstract

Abstract. Long-term hazard assessment, one of the bastions of risk-mitigation programs, is required for land-use planning and for developing emergency plans. To ensure quality and representative results, long-term volcanic hazard assessment requires several sequential steps to be completed, which include the compilation of geological and volcanological information, the characterisation of past eruptions, spatial and temporal probabilistic studies, and the simulation of different eruptive scenarios. Despite being a densely populated active volcanic region that receives millions of visitors per year, no systematic hazard assessment has ever been conducted on the Canary Islands. In this paper we focus our attention on El Hierro, the youngest of the Canary Islands and the most recently affected by an eruption. We analyse the past eruptive activity to determine the spatial and temporal probability, and likely style of a future eruption on the island, i.e. the where, when and how. By studying the past eruptive behaviour of the island and assuming that future eruptive patterns will be similar, we aim to identify the most likely volcanic scenarios and corresponding hazards, which include lava flows, pyroclastic fallout and pyroclastic density currents (PDCs). Finally, we estimate their probability of occurrence. The end result, through the combination of the most probable scenarios (lava flows, pyroclastic density currents and ashfall), is the first qualitative integrated volcanic hazard map of the island.

Highlights

The possibility of future eruptive activity, coupled with population growth and economic and cultural development in the majority of active volcanic areas, means that mitigative measures against volcanic risk, such as the development of volcanic hazard analyses, must be undertaken
Other procedures have been applied in order to assess volcanic hazards in Campi Flegrei, Italy (Lirer et al, 2001); Furnas (São Miguel, Azores) Vesuvius in Italy (Chester et al, 2002); and Auckland, New Zealand (Sandri et al, 2012). Compared with these previous approaches, our study offers a procedure that facilitates undertaking volcanic hazard assessment in a systematic way, which can be applied to other volcanic areas around the world
In this study we focus on El Hierro and conduct a longterm volcanic hazard assessment by taking into account spatial and temporal probabilities

Summary

Introduction

The possibility of future eruptive activity, coupled with population growth and economic and cultural development in the majority of active volcanic areas, means that mitigative measures against volcanic risk, such as the development of volcanic hazard analyses, must be undertaken. Volcanic hazard assessment must necessarily be based on good knowledge of the past eruptive history of the volcanic area, which will tell us “how” eruptions have occurred. It requires the spatial probability of occurrence of a hazard to be determined; i.e. Long-term hazard assessment is necessary to know how the eruption could be It is based on the past history of the volcano and the information needed comes from the geological record.

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Conclusion