Objectives: The world's population has become increasingly concentrated in large conurbations at high risk from volcanic hazards. European cities on explosive volcanoes and volcanic islands are particularly threatened by pyroclastic flows and tephra fall. Quantification of the risk associated with a range of eruption scenarios, the risk's potential impact, and risk mitigation are priorities. The EXPLORIS project addresses these issues by advancing scientific and technological capabilities (e.g. simulation codes, vulnerability databases, and probabilistic risk protocols) needed for volcanic risk assessment and mitigation. The project applies the techniques and methods to four European volcanoes representing a high risk: Vesuvius , Italy ; La Soufrière , Guadeloupe , France ; Sete Cidades, Azores , Portugal ; and Teide, Canary Islands, Spain . The aim is to provide examples of the capabilities for supporting officials in planning priorities and decision-making during volcanic crises.

Scientific achievements: The main scientific achievements obtained during the EXPLORIS project consist of the development of the three research infrastructures, or facilities, described in the project work plan together with their first applications to the project volcanoes. The three research infrastructures are: 1) the numerical simulation codes of explosive phenomena, 2) the vulnerability functions and databases, and 3) the probabilistic protocols for risk assessment. In more detail, new simulation models, based on a transient, 3D, and multiphase description of the phenomena and able to exploit the computing power of modern supercomputers, were completed and tested by applying them to well-known test cases. First 3D large-scale simulations of pyroclastic flows produced by the collapse of the volcanic column were produced by using the code PDAC. Similarly, two ash fallout codes, named FALL3D and VOL-CALPUFF, were completed and applied to describe the proximal and distal fallout of ash produced by the volcanic column. Parallely, more simple 1D/2D models of pyroclastic flows and ash fallout were used and applied for the first time to the island volcanoes. As far as the vulnerability functions are concerned, a complete set of studies aimed at the definition of building and human vulnerability relationships to the actions of earthquakes, pyroclastic flows, and ash fallout were produced. In particular, building vulnerability functions to dynamic pressure of the flow, isotropic pressure variations, missiles transported by the flow, tephra load on roofs, ash infiltration, fire potential, etc. were all defined. The effect of the combination of actions on buildings due to the contemporaneous presence of more than one phenomena was also investigated. Finally, probabilistic risk assessment protocols based on the development of event trees and expert elicitations were developed and first applications to the four project volcanoes completed. In addition, a first probabilistic risk assessment code able to combine hazard, vulnerability, and territorial data was completed. Applications of the tools and functions developed were performed in the last few months of the project at Vesuvius and some of the island volcanoes. Impact scenarios as well as probabilistic estimates of the different scenarios and hazardous actions expected, also including credible intervals, were for the first time carried out. Mitigation measures able to increase the resistance of building to the actions of explosive eruptions were also proposed and experimentally tested.

Main deliverables: 3D simulation codes, vulnerability functions, and probabilistic risk procedures were the main concrete volcanic risk facilities delivered by the EXPLORIS project. All these tools could be easily applied to other volcanic regions and therefore could be potentially exploited by the project. An additional important deliverable of the project was the reconstruction of the eruptive history of the four volcanoes as well as the quantitative definition of the possible scenarios expected in the form of logic Event Trees.

Socio-economic relevance and policy implications: The EXPLORIS project contributes directly to improve the quality of life of millions of people in high-risk European regions through the establishment of safer living conditions. In particular, the assessment of volcanic risk on a probabilistic basis, as well as the identification of possible mitigation measures, shall help in defining mitigation policies aimed at risk reduction for cities on volcanoes and volcanic islands.

Conclusions: The main aim of the EXPLORIS project consisted in the introduction of a new methodology and new tools in the quantitative assessment of volcanic risk in densely populated regions. This goal was fully achieved through the development of research facilities completely new for the volcanological community. The project also tried to stimulate new mitigation policies and decision support to the authorities responsible for the most dangerous European volcanoes. The results obtained are promising and increase the chances to significantly improve the assessment of volcanic risk at the four project volcanoes in the coming years.

Dissemination of results: Project results were disseminated by publication of papers in international journals (about 30 already printed and 25 submitted) as well as through presentations at national and international conferences (more than 100). In addition, a special issue of the Journal of Volcanology and Geothermal Research entitled "Evaluating explosive risk at European volcanoes" is in preparation with more than 15 contributions fully derived from EXPLORIS. Further dissemination of the project outcomes was carried out by the organization of several technical meetings with civil officials and authorities of the countries of the selected volcanoes as well as by the organization of a final EXPLORIS Workshop in Naples with the attendance of international recognized experts in volcanic risk.

Keywords: Volcanic risk, explosive eruptions, numerical simulations, pyroclastic flow, ash fallout, vulnerability relationships, probabilistic risk assessment protocols, Vesuvio, La Soufrière Guadaloupe , Sete Cidades Azores Islands, Teide Canary Islands, Soufrière Hills Montserrat.

In : J.M. Lindsay, S. Ali, R.E.A. Robertson, J.B. Shepherd & L. John (Eds) Volcanic Hazard Atlas of the Lesser Antilles, Seismic Research Unit University of the West Indies Trinidad

Annual workshop 2005: Quantifying volcanic activity Saint-Claude, Guadeloupe Sept. 19-24, 2005

Proceedings volume Working group of the European Seismological Commission and Observatoire Volcanologique et Sismologique de Guadeloupe (Institut de Physique du Globe de Paris) IAVCEI-IASPEI

Master's in GIS Engineering
ENSG

Master's in GIS Engineering Unpublished
ENSG

Report
1-53 pp

Coudret E,
JC. Komorowski, F. Beauducel

Oral presentation and discussion
Direction Départementale de l'Equipement
Cellule Aménagement du territoire et risques naturels and Guadeloupe institutional GIS users working group Basse-Terre Guadeloupe

Oral Present.

Geology Engineering degree IGAL
Cergy Pontoise

Geology Engineering degree IGAL
Cergy Pontoise unpublished

Cities on Volcanoes 3, Hilo Hawaii

Moderator of a scientific information session presented by U Cam and CAR research group (Baxter, Spence and associates) to elected officials, civil protection and Prefecture, and other institutional crisis managers and decision makers from Basse-Terre Souf. Guad Volcano.
Obs

Debate discussion

Moderator of a scientific information session presented by the
U Cam and CAR research group (Baxter, Spence and associates) to members of the medical and public health sector in Basse-Terre Basse Terre and St Claude Medical Center

Debate discussion

Atelier Antilles, Bilan et prospectives, 17-18 Septembre 2003, Institut National des Sciences de l'Univers, Centre National pour la Recherche Scientifique, Paris

Komorowski JC.,
G. Boudon,
E. Coudret,
M. Semet,
A. Le Friant,
B. Villemant,
X. Quidelleur,
F. Beauducel

Oral Presentation

Report 1-29 pp

Lo Savio S.,
A. Neri,
B.F. Houghton,
C. Bonadonna

Subduction et magmatisme dans l'arc des Petites Antilles Second workshop 1-3 june 2006-07-18 Céré la Ronde, France

Samper A.,
X. Quidelleur,
JC. Komorowski,
G. Boudon

AGU Assembly San Francisco December 2004

AGU Abstracts
EOS

Spence R.,
I. Kelman,
E. Calogero,
G. Toyos,
P.J. Baxter,
JC. Komorowski

Master's thesis
IPGP

Master's thesis Unpublished
IPG

Report
1-29 pp