Searching and detecting earthquake geochemical precursors in CO<sub>2</sub>-rich groundwaters from Galicia, Spain

DOI Web Site Web Site 2 Citations 120 References
  • PÉREZ NEMESIO M.
    Environmental Research Division, Instituto Tecnológico y de Energías Renovables (ITER)
  • HERNÁNDEZ P. A.
    Environmental Research Division, Instituto Tecnológico y de Energías Renovables (ITER)
  • IGARASHI G.
    Research Center for Prediction of Earthquakes and Volcanic Eruptions, Graduate School of Science, Tohoku University
  • TRUJILLO I.
    Instituto de Productos Naturales y Agrobiología de Canarias, Consejo Superior de Investigaciones Científicas (CSIC)
  • NAKAI S.
    Earthquake Research Institute, The University of Tokyo
  • SUMINO H.
    Laboratory for Earthquake Chemistry, Graduate School of Science, The University of Tokyo
  • WAKITA H.
    Laboratory for Earthquake Chemistry, Graduate School of Science, The University of Tokyo

Bibliographic Information

Other Title
  • Searching and detecting earthquake geochemical precursors in CO2-rich groundwaters from Galicia, Spain
  • Searching and detecting earthquake geochemical precursors in CO2-rich groundwaters from Galicia

Search this article

Abstract

The northwestern region of the Iberian Peninsula was traditionally considered a seismically stable area. However, the 1995 and 1997 Galicia earthquakes of magnitude 4.6 and 5.3 produced significant damage in the region (intensity EMS: V), and these events changed the seismic hazard map used for the building code in Spain. Searching for earthquake precursors of these seismic events was performed, and precursory geochemical signatures of the 1995 and 1997 Galicia earthquakes were detected. These precursory signatures were observed in CO2-rich groundwaters from a 120 m deep well at Cabreiroá (Ourense, Galicia), ∼90 km distance from the epicentres. Secular variations of the dissolved Cl- in these CO2-rich groundwaters showed clearly an increase trend three months before the occurrence of two earthquakes of magnitude 4.6 (November 29 and December 24, 1995) in Lugo (Galicia). After the precursory variations of Cl- prior to the earthquakes in 1995, a continuous radon monitoring system was installed at Cabreiorá's well. A significant increase of radon activity in the CO2-rich ground waters was detected four weeks prior to the magnitude 5.3 Galicia earthquake of May 21, 1997. Precursory changes in the chemical and isotopic composition of terrestrial fluids have been mainly attributed to the development of microcracks caused by the regional tectonic strain. The occurrence of these precursory geochemical signatures of CO2-rich groundwaters of magmatic origin in the NW Iberian peninsula probably suggests that high fluid pressure at depth play a major role in triggering earthquakes in the region.

Journal

Citations (2)*help

See more

References(120)*help

See more

Keywords

Details 詳細情報について

Report a problem

Back to top