Julie Fero NRS 509. Mapping Volcanic Risk with GIS

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1 Julie Fero NRS 509 Mapping Volcanic Risk with GIS Introduction Volcanoes are present throughout the world, generally occurring along plate margins, making the entire world prone to volcanic influence, whether directly or indirectly. However, the nations that are most vulnerable to natural disasters are developing countries. Many of the world s developing countries in Latin America and Asia are locate directly on a volcanic belt (Alcantara-Ayala, 2002). The development of a system to accurately assess volcanic risk in these regions is critical to public health and future development of these countries. Volcanic Hazards There are numerous volcanic hazards that can be destructive to property or pose a threat to human health. These hazards include lahars, debris avalanches, ash fall, release of volcanic gases, pyroclastic flows, lava flows and even tsunamis (Blong, 2000). Lahars are large mudflows that occur on a volcanic slope when water, often generated by melting of snow or ice during the eruption, mixes with loosely consolidated volcanic soil creating a deadly river of mud. Lahars have occurred during many of the prominent historical eruptions including the eruptions of Mt. Saint Helens, Mt. Pinatubo, and Nevado Del Ruiz (Rodolfo, 2000). The lahar generated at the eruption of Nevado Del Ruiz was especially devastating, killing over 23,000 people. Debris avalanches are large landslides formed during the eruptions. Often these avalanches include a large portion of the edifice of the volcano as observed at the beginning of the 1980 eruption of Mt. Saint Helens (Ui et al., 2000). Ash fallout from volcanic plumes can be very destructive to structures, crops, machinery, and power lines. Fumaroles that release toxic volcanic gases can be very hazardous to humans and livestock. Volcanic degassing of carbon dioxide from Lake Nyos claimed 1800 lives in 1986 (William-Jones and Rymer, 2000). Pyroclastic flows are liquidized flows of hot gas and particles that are deadly to anyone in their path. Tsunamis, such as the one that devastated the south Pacific last December, can be triggered by underwater eruptions or by volcanic material flowing into the ocean. Predictions of future volcanic hazards are often based on past volcanic activity of the region. Maps of previous lahar, avalanche, pyroclastic flow, and ash fallout deposits can be generated and used to show where these hazards are likely to occur again in the future. Additionally, elevation information can be extremely useful in predicting the flow path of a lahar or pyroclastic flow. Digital elevation models (DEMs) can aid in these predictions. Volcanic Risk Assessment The assessment of volcanic risk involves the compilation of volcanic hazard data with the addition of demographic data. The risk affecting a particular area is controlled by many factors including the population density, economic stability of the region, land use, and of course the potential volcanic hazards (Alberico et al., 2002). Only by combining all of these factors can the possible life and economic loss due to a volcanic event be evaluated. Knowing the potential risk of a region can help in disaster prevention and help the region recover after a disaster.

2 Role of GIS Volcanic risk assessment requires the assimilation and comparison of numerous data sets including maps of volcanic hazards, digital elevation models, and maps of demographic information (Pareschi et al., 2000). Geographical Information System (GIS) software can significantly aid in this process. Volcanic observatories worldwide are developing GIS databases to map the risks associated with the volcanoes in the region. For example, in the Azores, Gaspar et al. (2004) are working on developing a GIS database called AZORIS to map a wide variety of regional specific hazard and socioeconomic data. The GEOWARN database, currently under development, will eventually be a GIS database where information from a potentially active volcanic site can be entered to predict the potential hazards of the region (Gogu et al., In Press). Specifically GIS has been used to map hazards associated with pyroclastic flows at Campi Flegrei, Italy and Asama Volcano, Japan (Alberico et al., 2002; Kohsada, 2000). In Italy, GIS was used to integrate several different forms of data, including historical and current geological, geophysical, and geochemical data along with population density data. Alberico et al. then determined the areas of greatest volcanic risk. In Japan, Kohsada mapped historic pyroclastic flows and then overlaid a map of current roads and development to determine the regions of volcanic risk. Since pyroclastic flows follow the topography of the region, DEMs can be very useful in pyroclastic flow extent prediction. With a GIS database, DEMs can be easily integrated with historical hazard data, geologic data, and socio-economic data (Pareschi et al., 2000). Similarly, DEMs are useful when determining potential regions of lahar inundation. Iverson et al. (1998) used GIS software to calculate lahar hazard zones based on DEM data. Conclusions GIS is an essential tool for the mapping of volcanic risk zones. The capability of GIS to assimilate several sets of data into one comprehensive format allows for volcanic hazard potential to be easily compared with demographic information, such as population density. The use of GIS in assessing volcanic hazards is still fairly new, but I expect that the use of GIS within the field will soon become ubiquitous. I expect the future of volcanic hazard and risk management will continue to build upon the use of GIS. There are many active volcanoes, right here in the United States, that pose a hazard to the population. For example, Mt. Rainer could potentially produce devastating lahars in the Pacific Northwest. Many hazard zone maps of the region have already been produced, but as mapping technology, including GIS, improves, these hazard predictions will become more precise. References Alberico, I., Lirer, L., Petrosino, P. and R. Scandone, A methodology for the evaluation of long-term volcanic risk from pyroclastic flows in Campi Flegrei (Italy). Journal of Volcanology and Geothermal Research 116(1-2): Alcantara-Ayala, I., Geomorphology, natural hazards, vulnerability and prevention of natural disasters in developing countries. Geomorphology 47(2-4):

3 Blong, R., Volcanic hazards and risk management. In: H. Sigurdsson (Editor), Encylopedia of Volcanoes. Academic Press, New York, pp Gaspar, J.L., Goulart, C., Queiroz, G., Silveira, D. and A. Gomes, Dynamic structure and data sets of a GIS database for geological risk analysis in the Azores volcanic islands. Natural Hazards and Earth System Sciences 4(2): Gogu, R.C., Dietrich, V.J., Jenny, B., Schwandner, F.M. and L. Hurni, In Press. A geospatial data management system for potentially active volcanoes-geowarn project. Computers & Geosciences, In Press. Iverson, R.M., Schilling, S.P. and J.W. Vallance, Objective delineation of laharinundation hazard zones. Geological Society of America Bulletin, 110: Kohsaka, H., Risk prediction and evacuation-rescue plans for pyroclastic flow using GIS; a case study of the southern slope of Asama Volcano, Japan. Geographical review of Japan 73(6): Pareschi, M.T., Cavarra, L., Favalli, M., Giannini, F. and A. Meriggi, GIS and volcanic risk management. Natural Hazards 21(2-3): Rodolfo, K.S., The hazard from lahars and jokulhuaups. In: H. Sigurdsson (Editor), Encylopedia of Volcanoes. Academic Press, New York, pp Ui, T., Takarada, S. and M. Yoshimoto, Debris avalanches. In: H. Sigurdsson (Editor), Encylopedia of Volcanoes. Academic Press, New York, pp William-Jones, G. and H. Rymer, Hazards of volcanic gases. In: H. Sigurdsson (Editor), Encylopedia of Volcanoes. Academic Press, New York, pp

4 Annotated Bibliography Alberico, I., Lirer, L., Petrosino, P. and R. Scandone, A methodology for the evaluation of long-term volcanic risk from pyroclastic flows in Campi Flegrei (Italy). Journal of Volcanology and Geothermal Research 116(1-2): In this paper, the researchers utilize GIS ArcView 3.2 to assess the volcanic hazards at Campi Flegrei, Italy. An integration of historical geophysical data, geological data, and geochemical data with the population density of each region allowed for the calculation of the relative volcanic risk of each region. These data were then parameterized to provide a value for the relative hazard and urbanization of an area. The final maps show that the areas at highest risk for a volcanic disaster are the regions where a high hazard values overlaps a high urbanization value. The regions of highest risk are located within the caldera, corresponding with the town of Pozzuoli, and along the eastern part of the caldera, corresponding with the city of Naples. Since the hazard value is controlled by the proximity to the volcano, The only way to reduce the risk in these areas is to reduce the population density. Alcantara-Ayala, I., Geomorphology, natural hazards, vulnerability and prevention of natural disasters in developing countries. Geomorphology 47(2-4): This paper addresses a wide variety of natural hazards and emphasizes the importance of understanding the risk associated with each natural hazard. The disaster risk is dependent on the population density as well as the social and economic status of the population. Many developing countries are located in regions that are prone to natural disasters. For example many developing Latin American and Asian countries are located on active volcanic belts. This paper specifically looks at the association between geomorphology and natural disasters and discusses how GIS and other mapping tools are essential to assimilate the large amounts of data to determine hazard risk. Bukumirovic, T., Italiano, F. and P.M. Nuccio, The evolution of a dynamic geological system: the support of a GIS for geochemical measurements at the fumarole field of Vulcano, Italy. Journal of Volcanology and Geothermal Research, 79(3-4): In this paper data from a long-term survey of the summit crater of La Fossa, Italy were analyzed using GIS software. GIS enabled the analysis of long-term changes in the crater of volcanic gas output. The fumarole field was manually surveyed to provide a georeferenced dataset that could be digitized into GIS software. The node of each fumarole was then linked to a flux field database to enable the calculation the total output of a single fumarole for a specific area. The creation of this database has allowed for the comparison of fumarole activity with local tectonic activity and it was found that steam output and fumarole activity both increased during periods of tectonic unrest. Gaspar, J.L., Goulart, C., Queiroz, G., Silveira, D. and A. Gomes, Dynamic structure and data sets of a GIS database for geological risk analysis in the Azores volcanic islands. Natural Hazards and Earth System Sciences 4(2):

5 This paper discusses the development of a GIS database, called AZORIS, to map the risks associated with the active geology of the Azores volcanic islands. The paper focused on the development of this GIS database, including the methods used to digitize and georeference multiple datasets, to archive these data, and to create the metadata and other relevant data files. Geographic and socio-economic data, civil protection data, geologic data, volcanic data, seismologic data, geodetic data, fluid geochemistry data, and meteorological data were all included in the GIS database. The creation of this comprehensive database will allow for the analysis of risks associated with volcanic eruptions on the Azores islands. Additionally, having an established database will aid emergency response in the event of a disaster. Gogu, R.C., Dietrich, V.J., Jenny, B., Schwandner, F.M. and L. Hurni, In Press. A geo-spatial data management system for potentially active volcanoes-geowarn project. Computers & Geosciences, In Press. This paper deals with the development of a data management system to provide risk assessment of active volcanoes. The authors use two currently dormant but potentially active volcanic regions, the Kos-Yali-Nisyros-Tilos volcanic field in Greece and Campi Flegrei in Italy, as test cases for the new system. The database, called GEOWARN, utilized GIS to store and analyze a wide variety of spatial data. GEOWARN includes geographic data, geophysical data, geological data, and geochemical data. The development of this database will allow for future volcanic research and hazard assessment. Pareschi, M.T., Cavarra, L., Favalli, M., Giannini, F. and A. Meriggi, GIS and volcanic risk management. Natural Hazards 21(2-3): This paper examines the risks associated with two volcanic systems located in Italy, Mt. Etna and Mt. Vesuvius. These two volcanoes behave very differently, Etna is primarily an effusive system where Vesuvius is primarily explosive, and therefore the risk assessment must account for different parameters. Several different layers must be incorporated into the model making GIS the best application for volcanic risk management. The necessary layers include, digital elevation models, digital images from satellite or aircraft, vector data on surrounding features, hazard maps, and information on population density. The use of GIS is essential to assimilate these various data and produce volcanic risk maps.