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The role of depositional and post-depositional processes on sediment stability and mechanical behavior under dynamic seismic loading conditions in shallow subduction zone environments

English title The role of depositional and post-depositional processes on sediment stability and mechanical behavior under dynamic seismic loading conditions in shallow subduction zone environments
Applicant Strasser Michael
Number 118865
Funding scheme Fellowships for prospective researchers
Research institution MARUM Zentrum für Marine Umweltwissenschaften Universität Bremen
Institution of higher education Institution abroad - IACH
Main discipline Geology
Start/End 01.10.2007 - 30.09.2008
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All Disciplines (3)

Discipline
Geology
Geophysics
Other disciplines of Earth Sciences

Keywords (6)

subduction input; lithostratigraphy; earthquakes; sediment stability; cyclic triaxial shear test; integrated ocean drilling programm (IODP)

Lay Summary (English)

Lead
Lay summary
Active convergent ocean margins, where an oceanic plate is being subducted below a continental plate, are the Earth’s principle loci for earthquake, tsunami, volcanic and landslide hazards. A major part of the global population lives along the coast of active margins and, hence, understanding geological processes that govern nature and evolution of subduction zones and associated geohazards is a fundamental and societal relevant goal of modern Earth Science. An emerging and so far unanswered key question in understanding subduction zone evolution is the mechanical behavior of the sedimentary strata entering the “subduction conveyor belt” and its systematic change during progressive deformation.This study investigates the role of lithostratigraphic heterogeneities on the mechanical behavior with progressive deformation during early subduction along the Nankai Trough offshore SW Japan. These heterogeneities result from different depositional and post-depositional processes acting along this active continental margin. In particular, the study aims to shed light on the frictional stability of end-member lithologies under dynamic seismic loading conditions associated with great subduction thrust earthquakes and its effect on fault initiation and ocean margin slope stability. A series of undisturbed whole round samples from deep cores that will be drilled in the context of the Integrated Ocean Drilling Program (IODP) Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) will be analyzed with extensive geotechnical laboratory testing to evaluate the frictional sediment stability under cyclic loading conditions. This approach allows simulation of transient seismic stresses during earthquake shaking under controlled laboratory conditions, a concept that so far not was addressed specifically in analogue studies on the mechanical behavior of subducting sedimentary sections. Results from this study will contribute to our understanding on the role of different sedimentary processes on the mechanical evolution of shallow subduction zone environments. This will yield the means to evaluate frictional stability and down-dip changes in mechanical behavior of subducting sedimentary sections and will allow assessing sediment stability along the accretionary prism under seismic loading conditions.
Direct link to Lay Summary Last update: 21.02.2013

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