Design of specifications using Mount Cameroon data.
One of the objectives of MIAVITA WP 2 (i.e., Work Package 2: Knowledge database and Web-GIS design) is to examine the feasibility of a risk-scenarios-builder tool taking into account several geological hazards in a volcanic area. Such a tool is designed to assess the consequences of an eruption in terms of damage, taking into account the succession of volcanic, seismic, gravity and hydro-geological events. This is ultimately to be able to analyse the impact of such events for people, exposed elements (building, agriculture) and the various functional systems of the exposed communities. The expected result is the production of tables (or maps) providing an evaluation of human and exposed elements potential losses, but also an identification of the assets potentially impacted during the crisis and of their degree of damages. Such scenarios-building tools already exist in the field of seismic risk. They are used to evaluate potential human and economic losses due to a given earthquake scenario. They are used by the authorities and civil defence as supporting tool for crisis management exercises, or as decision support system for evaluating the scale of a possible crisis and of the response that they will need to bring for its management from the event to the reconstruction and return to a normal state of society.
Unlike the seismic risk for which the main obstacle to the development of scenario-tools is the complexity of the damage functions of the building to a peak ground acceleration, the volcanic risk scenarios face three specific challenges: (1) human and economic damage are not only related to the collapse of buildings, but to a large number of geological phenomena (lava, pyroclastic flows, landslides, lahars, etc ...) that can affect a multitude of exposed assets (people, building, agriculture, large regional functions…), (2) the many features of damage to integrate into a tool are also very heterogeneous and are poorly constrained by observations, (3) the tool should be able to take into account a multitude of successive or simultaneous events during the sequence of an eruption. The temporal dimension of the event is thus more complex than in the case of an earthquake scenario tool.
A preliminary work to develop a tool for volcanic scenario was conducted in spring 2011 (Engineering internship at Carolina Quinet BRGM) as part of the project MIAVITA. The objective of this work was to define the specifications of such a tool in a general context and then to submit an application through three pre-defined scenarios of eruption at Mount Cameroon. This work has shown that the different functions of existing damage can actually be ordered as part of such a tool, but also that the usual limits of the tools of scenarios, namely the fact that they can not assess the potential indirect damages, are here especially exacerbated because of the temporal dimension of the hazardous event.
Because of this, we think that scenarios builders are most useful for preparedness exercises and at the earliest stage of abrupt disasters. For longer term recovery, the assessment of factors of vulnerability of people remains the most important action to undertake. The development of the tool - suitable tool seismic risk scenario Armageddon - is scheduled for spring 2012.