Geodetic methods for detecting volcanic unrest: a theoretical approach |
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| Authors: | José Fernández José M Carrasco John B Rundle Vicente Araña |
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| Institution: | (1) Instituto de Astronomía y Geodesia (CSIC-UCM), Facultad de Ciencias Matemáticas, Ciudad Universitaria, E-28040-Madrid, Spain Fax: +3491 394 4607 e-mail: jft@iagmat1.mat.ucm.es, ES;(2) Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309, USA, US;(3) Museo Nacional de Ciencias Naturales (CSIC), José Gutiérrez Abascal, 2, E-28006-Madrid, Spain, ES |
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| Abstract: | In this paper we study the application of different geodetic techniques to volcanic activity monitoring, using theoretical analysis. This methodology is very useful for obtaining an idea of the most appropriate (and efficient) monitoring method, mainly when there are no records of geodetic changes previous to volcanic activity. The analysis takes into account the crustal structure of the area, its geology, and its known volcanic activity to estimate the deformation and gravity changes that might precede eruptions. The deformation model used includes the existing gravity field and vertical changes in the crustal properties. Both factors can have a considerable effect on computed deformation and gravity changes. Topography should be considered when there is a steep slope (greater than 10°). The case study of Teide stratovolcano (Tenerife, Canary Islands), for which no deformation or gravity changes are available, is used as a test. To avoid considering topography, we worked at the lowest level of Las Cañadas and examined a smaller area than the whole caldera or island. Therefore, the results are only a first approach to the most adequate geodetic monitoring system. The methodology can also be applied to active areas where volcanic risk is not associated with a stratovolcano but instead with monogenetic scattered centers, especially when sites must be chosen in terms of detection efficiency or existing facilities. The Canary Islands provide a good example of this type of active volcanic areas, and we apply our model to the island of Lanzarote to evaluate the efficiency of the monitoring system installed at the existing geodynamic station. On this island topography is not important. The results of our study show clearly that the most appropriate geodetic volcano monitoring system is not the same for all different volcanic zones and types, and the particular properties of each volcano/zone must be taken into account when designing each system. |
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| Keywords: | Volcanic unrest Deformation modeling Geodetic methods Volcano monitoring |
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