Japan Geoscience Union Meeting 2016

Presentation information

International Session (Poster)

Symbol S (Solid Earth Sciences) » S-TT Technology & Techniques

[S-TT18] Stress geomechanics: observations, modelings and implications

Sun. May 22, 2016 5:15 PM - 6:30 PM Poster Hall (International Exhibition Hall HALL6)

Convener:*HungYu Wu(Japan Agency for Marine-Earth Science and Technology), Chung-Han Chan(Earth Observatory of Singapore, Nanyang Technological University), Saneatsu Saito(Japan Agency for Marine-Earth Science and Technology), Yoshinori Sanada(Japan Agency for Marine-Earth Science and Technology), Ayumu Miyakawa(Geodynamics Research Group, Institute of Geology and Geoinformation (IGG), Geological Survey of Japan/AIST), Yasuhiro Yamada(Japan Agency for Marine-Earth Science and Technology (JAMSTEC), R&D Center for Ocean Drilling Science (ODS))

5:15 PM - 6:30 PM

[STT18-P01] Strain localization in accretionary prisms.

*Arthur Bauville1 (1.Department of Mathematical Science and Advanced Techology, JAMSTEC)

Keywords:strain localization, accretionary prism

Plate motion varies smoothly (over ~100 km) but results in localized (m to km scale) deformation near plates interface. Strain localization is caused by local stress variations and/or the response of the material to it. Generally, the localization of strain can have two different causes:
(1) A rheological cause, here termed dynamic strain localization. Thereby, strain in a homogeneous material becomes localized because the material softens in certain regions during the deformation (strain softening) due to processes such as grain size reduction, brittle precursor controlled fluid-rock interaction or shear heating.
(2) A structural cause, here termed kinematic strain localization. Thereby, the initial strength of the deformed region is heterogeneous and strain localizes due to initial differences in mechanical strength and/or due to particular geometries. Such localization of strain can occur in linear viscous materials.
Kinematic strain localization is still incompletely understood and may have a major importance (1) in subduction zones, where high sea floor topography is correlated with low plate coupling, i.e. large magnitude earthquakes are less likely to happen; (2) in fold-and-thrust belts where the geometry of the former margins can control the distribution and emplacement of tectonic nappes.
Here I present the results of 2D numerical simulations that demonstrate the importance kinematic strain localization on the structure of fold-and-thrust belts and accretionary prism. Early results towards a scaling law between sea floor topography, stress concentration and strain evolution are also presented.