Frontiers and Opportunities in Antarctic Geosciences * Certosa di Pontignano * 29-31 July 2004
C.
P
AREDES
*, R.
P
EREZ
, J.
G
INER
, J.J.
M
ARTÍNEZ
, R.
D
E LA
V
EGA
, S.
D
E
V
ICENTE
& C.
Q
UERAL
* Corresponding author ( cparedes@dmami.upm.es
)
Brittle rupture of the lithosphere scales at several sizes under the stress field according to the tectonic activity.
Multifractal networks of fracture sets are distributed in the space according to this geological settings. A threedimensional model of discrete fractures will be established in Deception Island (in the South Shetland group, Maritime
Antarctica) The principal aim of this project is the evaluation of the earthquake-volcanic hazard in the island according to the geothermal activity and thermohydraulic network. The proposed model assumes the three-dimensional network of fractures as the main vehicle of fluids and energy transport in low permeability geological media, e.g. volcanic islands.
Phase changes in the fluids are generated during this circulation. Geothermal surface activity or earthquakes and phreatomagmatic volcanic eruptions are triggered according this phase fluid changes. Hence, a potential geologic hazard emerge in areas of high volcanic activity character with presence of water, like the case of the Deception Island.
Therefore the scientific particular aims of the presented project are: (1) Design and perform of a discrete, threedimensional and conditional stochastic model of fractures, unpublished at the present time, in this island, from the geotectonic field information, radar and optical images. Modern modelisation and analysis techniques, such as multifractal methods, spherical statistics, etc. will be applied for this purpose. (2) Spatio directional correlation of the modelled field of fractures and their properties linked with seismicity, vulcanism and geothermalism data, and the active stress field. The purpose of this analysis is the identification of the sets of potentially active faults. (3) Definition of a mathematical model constrained by two-phase thermohydraulic processes according to the geothermal activity in the Island, by means of the combination of variations of enthalpy and phase change in fluids. The future calibration with the geothermal data sampled in surface will be applied over the simulated 3-D fracture network. The main utility of this model and their innovation is its direct integration of the geologic pattern over a mathematical model to applied the analysis of geologic hazard.
The results of this project are available for the simulation of geologic, seismic and volcanic hazard surveying models.
The model, as structural and mathematical point of view is a contribution itself, and the methodology here performed is exportable to any geographical area of similar phenomenology and geological settings ( e.g.
islands of volcanic origin in the national territory: Canary Islands).
This project does possible the coexistence of experts from several scientific areas, from the geologic characterisation to the applied mathematical modelling, serving as a birth of a modern and multidisciplinar scientific research team of international reaches. This is possible thanks to the demonstrated wide experience by each one of the members, by means of their holding in national and international investigation projects, as well as their high level of scientific and academic preparation.