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. C. Moore, Demian Saffer

Research output: Contribution to journalArticle

332 Scopus citations

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.

Original languageEnglish (US)
Pages (from-to)183-186
Number of pages4
JournalGeology
Volume29
Issue number2
DOIs
StatePublished - Jan 1 2001

All Science Journal Classification (ASJC) codes

  • Geology

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