development of a volcanic risk assessment …...development of a volcanic risk assessment...

Development of a volcanic risk assessment

information system for the prevention and

management of volcanic crisis: stating the

fundamentals

F. Gomez-Fernandez

Consiglio Nazionale delle Ricerche, CS Geol. Strutt. e Dinn.

del Appennino, via S. Maria 53, 56126 Pisa, Italy

EMail: [email protected]

Abstract

The variety of constraints that conventional methods devised to account forvolcanic risk have commonly faced, has limited the successful achievement ofthis kind of study. The detailed analysis and categorisation of the most commondifficulties found by classical volcanic risk assessments has allowed us toidentify the basic elements that risk calculation procedures would have toinclude to become efficient. Due to the operational improvement that theincorporation to the risk assessment context of technologies such as GIS andphysical simulation models can provide, the development of a volcanic riskassessment information system for early prevention and management ofvolcanic crisis has been considered. Because of the lack of a previous extensivebackground on the application of GIS for these purposes, a previous studyaimed at defining the procedures to be followed to analyse volcanic risk in theframe of a GIS has been carried out. In order to test the model devised, a pilotproject devoted to assess the risk posed by lava flows at Tenerife island (CanaryIslands, Spain) has been then carried out. Although the analysis of the resultsobtained indicates a good level of achievement of the objectives pursued, thecomplexity of the resulting calculation structure and the background knowledgerequired to manage it, make the system devised a tool difficult to master by theusers that could eventually benefit of the methodology developed. These factshave called attention upon the need to improve the communication with thesystem through a customised interface, capable of satisfying the users' basicinformation requirements. To achieve this new goal, a methodology for objectoriented design has been selected to define the basic architecture of the system.

1 Introduction

A major aim pursued by classical volcanological studies has been theproduction of hazard zonation maps on which the potential area ofinfluence of the volcanic phenomena considered and the existing socio-

Transactions on Information and Communications Technologies vol 18, © 1998 WIT Press, www.witpress.com, ISSN 1743-3517

112 GIS Technologies and their Environmental Applications

economic data available (such as lifelines, population centres, etc.) aredisplayed together in order to obtain information about the potential

losses in case of a volcanic crisis.The elaboration of such multiple hazard-multipurpose maps

(Foster*) has made up a priority requirement for volcanic riskassessments as they serve as the departing point from which theevaluation process begins. The selection of such a complex way to

display the information is based on the fact that, commonly, there is morethan one phenomenon susceptible to occur at any volcano and that the

risks created by each kind of impact pertain to more than one activity.As a result, there is the need to set in advance a clear series of

criteria for representation of all the elements and phenomena included toease the interpretation. Otherwise, it might become a difficult task either

because there is an excess of information displayed on the map or a too

schematic way to express it.Even taking into account the representation difficulties associated,

this mapping approach is, anyway, the most useful to follow when thereis the need to develop emergency, prevention and land use plans (Gupta

& Joshf).Nevertheless, the elaboration process followed is basically time

consuming and expensive due to the large amount of informationrequired to produce these outputs (Alexander*), what makes it difficult toreview or update the results of an assessment if unexpected events or newdata enter into play in the calculation.

Under this perspective, it would be desirable to find a way toreview and improve the existing map production methods in order toprovide an adequate solution to the current time and accuracy constraints

faced by, among other disciplines, volcanic risk assessments (Gupta &

Joshf).With this idea, we have considered the incorporation to the risk

maps generation process of a specific set of computer based tools,- suchas the Geographical Information Systems and the eruptive phenomenaphysical simulation models -, a feasible and realistic solution of the

assessment problems found by classical studies.The final aim pursued by our study is the development of a volcanic

risk assessment information system for early prevention and managementof volcanic crisis. The process followed to state the fundamentals fromwhich to construct such a system has been the object of this paper and isbriefly introduced through the next sections.


GIS Technologies and their Environmental Applications 113

2 A computer based volcanic risk assessmentmethodology

The successful level of performance that GIS methodologies applicationhas provided in other areas of risk assessment (e.g. epidemics control,

dispersal of toxic substances, etc.) and the substantial improvement in theknowledge of the behaviour of volcanic phenomena that existing physicalsimulation models have provided, have served us as the basis to considerthat the combination of both tools for volcanic risk assessment purposes

might provide a dynamic and powerful way to solve the commonconstraints to produce information that these studies have usually faced(G6mez-Fern&idez*).

GIS can contribute to improve the efficiency with their capacity to(1) store, retrieve and manage the large volumes of data to be analysed,(2) devise automatic data processing routines to allow fast calculation and

upgrading of the information and, (3) produce the high quality outputsrequired for assessment purposes.

On the other side, physical models have provided the way tosimulate eruptions and to obtain information on the extent and magnitudeof their effects (Pareschi & Berstein*), having already been consideredthe possibility of integrating them into the GIS architecture to help withhazard calculation (Lam and Swayne ).

Nevertheless, although computerization can help handle the largeamount of information needed, it can also lead to artificiality unless theultimate goal pursued by the studies is clearly stated and the methodologyto follow to achieve our objectives is detailed previously (Alexander*).

For this reasons, due to the new working environment that theincorporation of GIS and physical models offer to volcanic riskassessment in comparison with conventional methods, the design andtesting of a methodology, where the elements and procedures to be

followed to produce the information required by the assessments wereclearly identified, has become a primary step in order to achieve theimprovement of the current production methods.

2.1 Methodological background

Classical volcanic risk assessments have usually been forced to appeal toa variety of calculation methods that require to gather and analyse largeamounts of data of diverse nature.

Furthermore, the scarce data availability that usually characterisesvolcanic areas and the limited technical means that conventional methods



have at disposal to process these data, have in many cases led the studiesto assume certain methodological simplifications that have ultimately

hindered the achievement and completion of accurate risk assessments

(G6mez-Fern3ndez & Arafia-Saavedra ).The lack of a widely accepted standard methodology to follow to

carry out volcanic hazard and risk assessments has prevented us fromhaving a development basis from which to select and adapt its mostrelevant features to the GIS working environment.

For this reason, there has been the need to peer review the completeset of assessment methods followed by classical studies in order toidentify the most significant elements required to carry out volcanic riskestimation and to devise a way to represent these elements into the GIS

frame.The procedure followed to carry out these tasks has been based on

the principles and techniques proposed by cartographic modelling

methodologies (e.g. Tomlin*), which have given us the possibility ofdecomposing hierarchically the problem of risk assessment into each of

its components.

2.2 Methodology design

As a first step in the development of the methodology, a detailed analysisof the factors and variables that play a major role in volcanic risk and theway they relate to each other has been required.

The results obtained from this analysis have served us as thedeparting point from which the databases and the operations required tocarry out the volcanic risk assessment in the frame of a GIS have been

identified.The methodology designed makes use of a series of parameters

called volcanological and environmental variables to identify the eruptivephenomena taken potentially place at a vent of our selection, togetherwith their eruptive styles and the conditions existing for the dispersal oftheir products (G6mez-Fem&ndez*).

This set of data provide the input parameters to the correspondingphysical simulation models, which provide the way to calculate thedistribution of the products of a certain phenomenon of our interest. Thesimulation process produces an hazard map called commonly riskscenario (figure 1), where the results of the calculation are usuallyrepresented in probabilistic terms.

The analysis of the potential effects of the eruption simulated on theelements located in the area identified by the risk scenario constitutes the



VOLCANOLOG1CALVARIABLES

ENVIRONMENTALVARIABLES

Potential Eruptive Styles Conditions for dispersalof the products

PHYSICAL ERUPTIONMODELS

RISK SCENARIO

POTENTIAL RISK

Value of goods andproperties Vulnerability

SOCIO-ECONOMICVARIABLES

SUSCEPTIBILITYVARIABLES

Figure 1. Schematical representation of the process designed toassess volcanic risk



last stage of the risk assessment process. To achieve this objective,information on the value of the goods, properties and population of thearea affected and on the vulnerability of each of them against the

phenomenon represented in the risk scenario must be acquired. Thisinformation is provided by means of a series of socio-economic variables.

The results of confronting the scenario with the socio-economicvariables provide information on the potential risk, understood as themeasure of the value that can be lost or affected directly or indirectly as a

consequence of a certain event.

2.3 Methodology application

In order to check the design of the calculation structure developed, to testits efficiency and accuracy and to identify the main constraints facedwhen applied to an actual assessment, a pilot study at Tenerife island

(Canary islands, Spain) has been carried out.The aim pursued by this analysis has been: (1) to assess the risk

posed by lava flows proceeding from the occurrence of effusive eruptions

occurring at several points of the island and, (2) to compare the potential

distribution of the flows and the extent of damage produced depending on

the location of the eruptive vents selected and the socio-economiccharacteristics of the areas affected (G6mez-Fern£ndez*).

With this purpose, the model developed has been implemented in asystem where ILWIS has been used as the GIS software basis. Due to thefact that the study has been limited to the assessment of one eruptivephenomenon, only the databases and the physical model required to carryout lava flows risk analysis have been considered for inclusion in the

system (figure 2).In the process of construction of the system, special emphasis has

been given to the production of outputs in order to assure that the time,interpretability and accuracy constraints found by conventional methodscould be solved.

To provide comprehensible information regarding the results of the

simulation and of the potential risk assessment process, the systemimplemented generates automatically for each event simulated a series ofgraphical and tabular outputs that provide information on: (1) thepotential distribution of the lava flow paths identified by the modeltogether with additional contextual information to aid interpretation, (2)the distribution and characteristics of each of the socio-economicvariables located in the potential affected and buffer areas and an estimateof their potential losses and, (3) a synthetic potential risk map that


CIS Technologies and their Environmental Applications 117SOCTOECONOMIC DATABASES

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includes the information regarding the magnitude of the potential lossesof each element affected by the flows and attached explanation tables

(figure 2).

2.4 Methodology constraints and future developments

The results provided by the application of the methodology have beendiscussed and analysed taking into account: (1) the conditions establishedfor the implementation of the model, (2) the characteristics of the

methodology devised to carry out volcanic risk assessment and, (3) the

computer tools selected for its development (G6mez-Fern£ndez*).This thorough analysis has provided us the way to identify the

constraints that the method devised has found for the achievement of theobjective pursued with the incorporation of GIS and physical models tothe volcanic risk assessment calculation, i.e. the improvement of the

methods to produce information.Basically the methodology devised has provided the way to

surmount the time, interpretation and accuracy constraints faced byclassical assessments, due to the sensible reduction achieved for the

calculation times, the improvement on the quality of the outputs producedand the establishment of a clear identification of the variables andprocedures that play a role in the risk assessment process.

In spite of the substantial improvement that the methodologydevised has signified in general terms, there are two features that need tobe accounted for in future developments as they have been revealed asfundamental to give an operational character to the assessment method.

First, there would be the need to consider a complete physical

integration of the simulation models into the structure of the system as, atthis phase of the study, its independence has slowed down the process ofcalculation, due to the need to create additional procedures to exchangedata and parameters between them and the GIS.

Furthermore, during the application of the system it has beenstressed the need of an adequate user interface to provide communication

between the user and the system. Without it, advanced technical skills tomanage the tools used and the methodology devised are required, whatmakes it a technique difficult to access by inexperienced users.

Therefore, the development of an operational and powerfulinformation system will depend basically on the achievement to includethese goals in its design.



3 Statement of the volcanic risk assessmentinformation system development strategy

The development of the methodology for volcanic risk assessment thathas been presented through the previous section has provided us with anefficient solution to the performance constraints that classical studiesused to find to produce volcanic hazard or risk maps.

Moreover, this practice has allowed us (through the application ofthe methodology to a specific case study) to acquire a basic technicalknowledge of the needs that a general user would expect from a system ofthese characteristics, speaking in terms of: (1) the way to communicatewith the system and to require information from it, (2) the kind of

information expected to obtain from the calculation processes and, (3) theway to display these results.

At this point, the main aim to be achieved by future research workhas passed to be the development of an information system capable ofachieving the specific series of system requirements which can beextracted from the analysis of these needs. The adoption of thisperspective can help us also to solve the troubles faced during theapplication of the methodology.

To carry out this task, the assumption of an object orientedapproach to develop the software has been considered the most efficientway to construct a solid system architecture.

Nevertheless, due to the wide user community that can benefit fromthe such a system (civil defence officers, insurance companies, land usemanagers, etc.), all of them with a different scope of the informationrequired from it, we have limited by the moment the scope of the

application to the production of the information required to elaboratevolcanic risk prevention and management plans.

Acknowledgements

The labour presented in this paper has been carried out, first under theauspices of the Teide Project: European Laboratory Volcano, funded bythe Environment Programme of the EU-DG XII (Science, Research andDevelopment) and, currently under a Marie Curie Research TrainingGrant, awarded by the same sources.

Thanks are also due to the researchers involved in the Teide project,to the Cabildo Insular de Tenerife, the Institute Geogrdfico Nacional andto the local and national Protecci6n Civil services, either at itsheadquarters or their branches at the Canary Islands.



References

[1] Foster, H.D., Disaster planning: the preservation of life and property,Springer, New York, 1980.

[2] Gupta, R.R & Joshi, B.C., Landslide hazard zoning using the GISapproach - a case study from the Ramganga catchment, Himalayas.

Engineering Geology, 28, pp. 119-131. 1990.

[3] Alexander, D., Natural Disasters, UCL Press, 1993.

[4] G6mez-Fern&idez, P., Desarrollo de una Metodologia para el

Andlisis del Riesgo Volcdnico en el Marco de un Sistema deInformacion Geogrdfica, PhD Thesis (unpub.), Facultad de CienciasGeol6gicas, Universidad Complutense de Madrid, 1997.

[5]Pareschi, M.T. & Berstein, R., Modeling and image processing for

visualization of volcanic mapping, IBM Journal of Research and

Development, 33 (4), pp. 406-416,1989.

[6]Lam, D.C.L. & Swayne, D..A., Integrating database, spreadsheet,graphics, GIS, statistics, simulation models and expert Systems:experiences with the Raison system on microcomputers. NATO ASISeries G26, pp. 429-459, 1991.

[7] G6mez-Ferndndez, F. & Arafia-Saavedra, V., Design and development

of a GIS volcanic risk assessment methodology for the prevention,

management and mitigation of volcanic crisis, Submitted.

[8]Tomlin, C.D., Cartographic Modelling, Geographical InformationSystems, eds. D.J. Maguire, M.F. Goodchild & D.W. Rhind, Vol. 1,pp. 361-374, 1991.


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