Updip limit of the seismogenic zone beneath the accretionary prism of southwest Japan: An effect of diagenetic to low-grade metamorphic processes and increasing effective stress

J. Casey Moore; Demian M. Saffer

doi:10.1130/0091-7613(2001)029%3c0183:ulotsz%3e2.0.co;2

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Updip limit of the seismogenic zone beneath the accretionary prism of southwest Japan: An effect of diagenetic to low-grade metamorphic processes and increasing effective stress

J. Casey Moore·Demian M. Saffer

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Abstract

Off southwest Japan the seaward limit of coseismic displacement (or updip limit of the seismogenic zone) of the 1946 M w 8.3 thrust earthquake reaches to 4 km depth and ∼40 km landward of the trench. This limit coincides with the estimated location of the 150 °C isotherm, and has been linked to changes in physical properties associated with the smectite to illite clay-mineral transition. Here we show that this limit correlates with a suite of diagenetic to low-grade metamorphic processes characterized by (1) declining fluid production and decreasing fluid pressure ratio (λ * ) and (2) active clay, carbonate, and zeolite cementation and the transition to pressure solution and quartz cementation. These diagenetic to low-grade metamorphic changes cause the onset of velocity weakening during thrust faulting, an increase in effective stress, and strengthening of the hanging wall, which together combine to produce recordable earthquakes.

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Geology Article

Source-reported bounding extent: 31.5° to 34.5° latitude; 132° to 137° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

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BibTeX RIS

J. Casey Moore, Demian M. Saffer. 2001. Updip limit of the seismogenic zone beneath the accretionary prism of southwest Japan: An effect of diagenetic to low-grade metamorphic processes and increasing effective stress. https://doi.org/10.1130/0091-7613(2001)029%253c0183%3Aulotsz%253e2.0.co%3B2

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