Dehydration and earthquakes in the subducting slab: Empirical link in intermediate and deep seismic zones

Soichi Omori, Tetsuya Komabayashi, Shigenori Maruyama

    Research output: Contribution to journalArticle

    87 Citations (Scopus)

    Abstract

    In this study, a close link between the depth-distribution of subduction-zone earthquakes and dehydration events in the hydrated slab-peridotite is established. A phase diagram up to 27 GPa in the MgO-Al2O3-SiO2-H2O (MASH) system was constructed using a combination of thermodynamic calculation and Schreinemakers analysis on previous experimental data. At intermediate-depths (<250 km), dehydration of antigorite, talc, brucite, clinochlore, and Mg-sursassite occur. In the 200-500 km depth-range, dehydrations of Mg-sursassite and brucite+phase D are possible. Dehydration of brucite and dense hydrous Mg-silicates (phase E, D and superhydrous phase B) occurs in the mantle-transition zone. Since conditions for dehydration are dependent on slab temperature, we constructed diagrams illustrating the distribution patterns of dehydration events at several model slab-temperatures. In parallel to the mineralogical study, the depth-distribution of global subduction-zone earthquakes are compiled into a thermal parameter-depth diagram and compared with the dehydration event distributions determined previously. The distribution of dehydration events and earthquakes are comparable in terms of: (1) non-linear correlation between the maximum depth of earthquake and temperature of the slab, (2) an aseismic zone at 300-600 km depth in medium- T subduction zones, and (3) lack of deep-earthquakes in young subduction-zones. Considering those links, we propose an extended dehydration-induced earthquake (EDIE) hypothesis that considers any dehydration event has a potential to induce earthquakes in the subducting slab peridotite.

    Original languageEnglish
    Pages (from-to)297-311
    Number of pages15
    JournalPhysics of the Earth and Planetary Interiors
    Volume146
    Issue number1-2
    DOIs
    Publication statusPublished - Aug 16 2004

    Keywords

    • Deep focus earthquake
    • Dehydration
    • Earthquake
    • Phase relation
    • Subduction-zone

    ASJC Scopus subject areas

    • Astronomy and Astrophysics
    • Geophysics
    • Physics and Astronomy (miscellaneous)
    • Space and Planetary Science

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