Volcanic Crisis Management and Mitigation Strategies: A Multi-Risk Framework Case StudyGiulio Zuccaro, Mattia Leone Study Centre PLINIVS – University of Naples “Federico II”, via Toledo, 402 – 80134 Naples, IT [email protected], [email protected]Background Natural phenomena such as earthquakes, mud floods, landslides, volcanic eruption or industrial accidents may cause huge disasters. Each crisis generally determines consequences in multiple sectors and systems (e.g. building and infrastructures, roads and public transport, lifelines and telecommunication, society and emergency management.) that are singularly affected by the triggering event, but also may be hit by effects following the main one, the so-called “cascading effects.” Therefore, the methodological approach to the risk analysis of a single event made by the classical probabilistic convolution of Hazard, Vulnerability and Exposure has to be appropriately modified. Consequently, in order to produce effective tools addressing these issues, dynamic multi-hazard evaluation, time-dependant vulnerability functions of the element at risk under examination, and its exposure evolving in time and space, are required. Systemic studies on hazard, vulnerability and exposure have become the main field of investigation and have to be embedded within a multi-risk assessment approach. Multi-risk in fact is more than a simple aggregation ofsingle risks, due to the possible amplification of risk indexes due to interactions among different hazards and/or cascade events. In this field, only few studies have been conducted and ongoing research still needs considerable efforts. The tools available for foreseeing crisis evolution are specific to each hazard and therefore the actual best practice for decision makers involved in extreme crisis management is to evaluate possible management sub-plans by comparing potential losses starting from a synoptical view of single risks. Nevertheless, the single risk modeling approaches, based on different hazard models and on the estimation of impacts on typologically different systems at risk, often referring to different space and time scales that determines different model scales and input/output data, may lead to incomparable estimations of risk, ranging from mere indices to complex assessments. Moreover, often only the average of the estimated risk distribution is provided, not accounting for confidence boundaries of the estimation, and at the same time heterogeneity of available input data and models could be accompanied by inhomogeneous uncertainties invalidating risk comparability. The volcanic hazard represents a relevant research issue in the field of multi-risk assessment and management, as it embodies a possible well-defined sequence of disastrous events (i.e. a Sub-Plinian event is characterized by the following phases: several seismic tremors and earthquakes during the unrest phase, ash fall, bombs and gas emission during the eruption, pyroclastic flows at the end of the eruption and lahars after the eruption), which in turn can lead to cascading effects in multiple systems. An effective Disaster Operations Management (DOM) tool and its support to decision-makers should then be focused on a dynamic evolution of the risk, in order to minimize the physical and economic losses, especially in the case of Low probability of Occurrence of main event (LO) and High socio economic Impact (HI) of the expected losses. In this case, the effect of long-term mitigation strategies, as well as short-term recovery sub- plans, depending on existing capabilities and on their possible altered availability during the event, should be
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Volcanic Crisis Management and Mitigation Strategies
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8/3/2019 Volcanic Crisis Management and Mitigation Strategies
Natural phenomena such as earthquakes, mud floods, landslides, volcanic eruption or industrial accidents may
cause huge disasters. Each crisis generally determines consequences in multiple sectors and systems (e.g. building
and infrastructures, roads and public transport, lifelines and telecommunication, society and emergency
management.) that are singularly affected by the triggering event, but also may be hit by effects following the
main one, the so-called “cascading effects.”
Therefore, the methodological approach to the risk analysis of a single event made by the classical probabilistic
convolution of Hazard, Vulnerability and Exposure has to be appropriately modified. Consequently, in order to
produce effective tools addressing these issues, dynamic multi-hazard evaluation, time-dependant vulnerability
functions of the element at risk under examination, and its exposure evolving in time and space, are required.
Systemic studies on hazard, vulnerability and exposure have become the main field of investigation and have to
be embedded within a multi-risk assessment approach. Multi-risk in fact is more than a simple aggregation of
single risks, due to the possible amplification of risk indexes due to interactions among different hazards and/or
cascade events. In this field, only few studies have been conducted and ongoing research still needs considerable
efforts.
The tools available for foreseeing crisis evolution are specific to each hazard and therefore the actual best practice
for decision makers involved in extreme crisis management is to evaluate possible management sub-plans by
comparing potential losses starting from a synoptical view of single risks. Nevertheless, the single risk modeling
approaches, based on different hazard models and on the estimation of impacts on typologically different systems
at risk, often referring to different space and time scales that determines different model scales and input/output
data, may lead to incomparable estimations of risk, ranging from mere indices to complex assessments.
Moreover, often only the average of the estimated risk distribution is provided, not accounting for confidence
boundaries of the estimation, and at the same time heterogeneity of available input data and models could be
accompanied by inhomogeneous uncertainties invalidating risk comparability.
The volcanic hazard represents a relevant research issue in the field of multi-risk assessment and management, as
it embodies a possible well-defined sequence of disastrous events (i.e. a Sub-Plinian event is characterized by thefollowing phases: several seismic tremors and earthquakes during the unrest phase, ash fall, bombs and gas
emission during the eruption, pyroclastic flows at the end of the eruption and lahars after the eruption), which in
turn can lead to cascading effects in multiple systems.
An effective Disaster Operations Management (DOM) tool and its support to decision-makers should then be
focused on a dynamic evolution of the risk, in order to minimize the physical and economic losses, especially in
the case of Low probability of Occurrence of main event (LO) and High socio economic Impact (HI) of the
expected losses. In this case, the effect of long-term mitigation strategies, as well as short-term recovery sub-
plans, depending on existing capabilities and on their possible altered availability during the event, should be
8/3/2019 Volcanic Crisis Management and Mitigation Strategies
fully evaluated with a decision management perspective. In this sense a crucial aspect of the dynamic predictive
model is the time-dependant vulnerability curves able to estimate the cumulative damage of the considered
element at risk by combining the actions of a sequence (seismic crisis) or of the contemporaneity of events
(earthquakes with ash on the roofs).
Volcanic Crisis and Disaster Management
Research activities about the effects of a volcanic eruption on existing buildings and infrastructures have
produced in the last 15 years a comprehensive framework of studies, surveys and simulations, showing the
several uncertainties related to the exact prediction of the eruption type which should be expected (especially in
the case of active volcanoes in rest phase), and the many implications that different eruptive phenomena can have
on emergency-plan strategies and on built-environment planning and refurbishment.
Nevertheless, in order to address possible DOM (Disaster Operation Management) actions and mitigation
strategies in volcanic risk-prone areas, a different approach is needed, starting from the basic consideration that
the cumulative effects given by a complex eruptive scenario (such as a Sub-Plinian or Plinian eruption) produce
extremely variable impacts on the territory, and depending on the specific time history of the event (i.e. the
specific sequence of hazards, from precursory seismic tremors, to ash fall and pyroclastic flows), the prevailingbuilding typologies in the invested areas, and their level of vulnerability (i.e. masonry or R.C. structures).
Figure 1: Hypothetical Time History for a Sub-Plinian Eruption at Vesuvius.
This peculiar approach has been recently formalized in order to evaluate the impact of a Sub-Plinian eruption in
Vesuvius and Campi Flegrei area (Zuccaro et al., 2008, 2009, 2010, Baxter et al. 2008), through the development
of a numeric model for the definition of impact scenarios.
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crisis and this could affect sensibly the actuation of the Civil Protection Management Plan (CPMP) up to his
failing.
In order to clarify the level of complexity of disaster-management planning in case of volcanic eruption, it is
possible to highlight the main issues associated only with the first phase of the emergency. In fact, during the
unrest phase (of which the duration is the first uncertainty) many premonitory tremors and possibly some
damaging earthquakes are expected. Therefore, the actual vulnerability assessment of the buildings in the area issupposed to change along the unrest phase by cumulating damages due to the seismic actions that precedes the
eruption (Figs 3a and 3b). This could affect the success of the evacuation because of:
• lack of practicability of the road system obstructed by building rubbles;
• emotional pathos of the population disrupted by an emergency (seismic) in another emergency
(volcanic);
• management difficulties to rescue the people trapped;
• management difficulties to evacuate relatives of missing people;
• lifeline failures during the management of the seismic crisis preceding the evacuation;
• over-loading of the health facilities in the area and surrounding areas to be evacuated;
• critical management of the information system.
Figure 3a: Detail of Vesuvius Red Zone: Impact of pre-event seismic actions on evacuation roads practicability.
In this case, the decision-makers are faced with the necessity to evaluate the dynamic changes of the system status
along the crisis. Therefore, a time-dependent risk assessment is required, along with the evaluation of the
variation laws that govern the status along the time history assumed for the several involved systems, such as:
• seismic hazard probability and the dependent eruption probability;
• vulnerability of the buildings facing the escaping ways;
• distribution of building class typologies on the territory;
• total inhabitants and occupants per building type during day/night hours, etc.;
• roads network and critical facilities inventory: lifelines, resources system and their capacity data
(hospitals, fire stations, ambulances, helicopters, etc.);
• additional usable resources in “peace time.”
The model can be used as a DOM (Disaster Operation Management) tool, to build up a framework of interactionsbetween the systems involved in the specific crisis considered. The model provides, by means of a full
probabilistic approach, the variation of the impact scenario according to the variation during time of the single
sub-system, its distribution in space and its influence on the others subsystem interrelated.
Out-of-service road system branches and related no-escape areas are determined. Making use of the hypothetic
flow models, traffic intensifications also are determined. Moreover, hypothetical electrical service disruption and
gas lines breakings for potential serious inconveniences and/or cascading hazardous effects are determined
(systemic vulnerability) involving air transport, trains, etc.
Based on this set of information, the model is able to produce several alternative scenarios at selected times along
the event time history, in order to compute an impact evaluation (expressed as casualties, direct physical
damages, costs, indirect economic consequences, etc.) to compare the consequences of potential decisions taken
(i.e. evacuation of population) during the crisis. The model considers also the probability of variations in damage
scenarios consequent to assumed mitigation actions, including the evaluation of the direct, indirect and social cost
of each single management action.
The results should be the potential evaluation of a dynamic risk assessment in time and space along the crisis,
giving elements to the decision-makers for steering the action to undertake.
Mitigation Strategies and Cost-Benefit Assessment
Studies carried out at PLINIVS, in collaboration with DPC and Campania Region, show how the implementation
of mitigation strategies can significantly decrease the expected damage after an eruptive event. Even the impacts
of high destructive type of eruptions, such as Sub-Plinian, can be strongly reduced by effective planning strategiesor mitigation measures on buildings and infrastructures, responding to the different eruptive phenomena, such as
earthquakes (EQ), pyroclastic flows (PF), ash fall (AF) and lahars (LH).
The first domain, related to territorial planning strategies for volcanic risk-prone areas, is connected to some basic
regulatory issues that should be faced within local planning and development, introducing the volcanic risk
mitigation opportunities into existing or updated building codes.
This raises new issues previously only slightly treated in territorial planning. Incentives to the population to leave
the area should be supported by new strategies for the Red Zone, considering how moving many people requires
intensive studies for delocalization of residential and productive areas. Some industries and sensible functions
would need to be delocalized. But at the same time, having in mind the financial assessment of such operations, it
should be clear which kind of use could be envisaged for the new “free” areas in the Red Zone (i.e. urban parks,seasonal and touristic structures, etc.), in order to limit the economic damage to the area due to the loss of people
and productive activities. In territorial contexts different from Vesuvius and Campi Flegrei area (characterized by
high environmental and archeological constraints to transformation), damage scenarios also can be integrated in
advanced territorial planning, suggesting densification and a-densification strategies based on expected impact on
the different areas.
A second field of intervention is the one related to the strengthening and protection of building and infrastructures
at risk. PLINIVS model considers different mitigation technologies for building structures and envelopes as
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A dynamic tool that provides the probabilistic evaluation of the consequences of the possible strategies adopted
by the decision-makers, before/during/after the crisis (false alarm included), is missing at the moment. Different
decisions could affect the damage scenarios consequent to a single eruptive event (that represents a cascade of
events by itself). In this aim, the simulation models already available, and mentioned in this paper, consider the
cumulative damage on the elements at risk phase after phase (time-dependent vulnerabilities are considered).However, they do not take into account cascading effects that could be triggered during a crisis because of lack of
decision or inappropriate decisions.
At the moment, there aren’t models able to describe as a whole the multi-sectorial consequence of an intervention
action of the civil protection along the crisis, nor established models able to describe the risk associated to
cascading events (multi-risk models) triggered by a wrong managing of an originating adverse event. The
decision-maker should be supported by a tool able to represent, through a number of scenarios, what would be the
effects of each action. Those scenarios ought to be built considering evolving risk in a multi-risk dynamic
approach where the input is also the alternative action of the crisis management.
Future research projects at the European level should take into account this new approach in order to give a first
answer to the need of standardization of emergency management, especially when for Low Hazard a High Impact
is expected.
References
• Neri, A., Esposti Ongaro, T., Macedonio, G., Gidaspow, D., 2003. Multiparticle simulation of collapsing
volcanic columns and pyroclastic flows. J. Geophys. Res. Lett. 108, 2202.
• Macedonio G., Costa A., Folch A. 2008 Ash fallout scenarios at Vesuvius: numerical simulations and
implications for hazard assessment, J. Volcanol. Geotherm. Res.
• Convertito, V. and Zollo, A. 2008. Assessment of pre- and syn-crisis seismic hazard at Vesuvio and Campi
Flegrei volcanoes, Campania region southern Italy.
• G. Zuccaro, F. Cacace, R. J.S. Spence, P. J. Baxter, “Impact of explosive eruption scenarios at Vesuvius”,
Journal of Volcanology and Geothermal Research 178 (2008) 416–453.
• P.J. Baxter , W.P. Aspinall , A. Neri , G. Zuccaro, R.J.S. Spence, R. Cioni, G. Woo, “Emergency planning and
mitigation at Vesuvius: A new evidence-based approach”, Journal of Volcanology and Geothermal Research 178
(2008) 454–473.
• G. Zuccaro, 2009 “A probabilistic Model for the evaluation of the impact of explosive eruption scenarios at
Vesuvius”, in Urban Habitat Constructions under Catastrophic Events – COST action C26 – F. Mazzolani et al.
Editors. Conferenza COST 26 in Malta 2008 – Pubblicata 2009.
• G. Zuccaro, F. Cacace – 2010, “Seismic impact scenarios in the volcanic areas in Campania” , Proceedings of
“COST Action C26- Final Conference” Urban Habitat Constructions under Catastrophic Events – Mazzolani