The role of subducting plate rheology in outer-rise seismicity: Implications for Japan and South American subduction systems
Bound Volume Number
Honors Capstone Project
Date of Submission
Dr. Robert Moucha
Dr. Gregory Hoke
Arts and Science
outer rise, lithospheric plate, numerical modeling, tensile deformation, Japan, South America
Capstone Prize Winner
Won Capstone Funding
Sciences and Engineering
Geology | Geophysics and Seismology | Tectonics and Structure
The outer rise is a subtle ridge on the seafloor located near an oceanic trench where a down-going lithospheric plate begins to bend and thus fault prior to subducting at the subduction zone. During subduction, the descending lithospheric plate bends upwards, leading to normal faulting. This normal faulting, or deformation pattern, is hypothesized to be controlled by the subducting plate’s age, rheology, subduction velocity and angle. The two main goals of this study were to: 1) numerically model the influence of plate age, subduction angle, plate speed, and rheological parameters on outer-rise tensile deformation, and 2) characterize the regions of tensile deformation and compare these to the subducting plates in northeastern Japan and South America. I observed significant differences in the lateral extent and modest variations in the vertical extent of the outer-rise deformation region that I primarily attribute to differences in the imposed subduction angle representative of the two geographical locations. With a steeper subduction angle, the material has a more compact area to deform in, thus creating a deeper “wedge” of deformation. The rheological properties, however, play a more significant role in the lateral spread of the deformation. As a model’s internal friction angle increases, its ability to deform decreases, resulting in a narrower section of deformation. Also, the cohesion of the models lead to the observation that a more cohesive, or unified material, had more difficulty deforming than those that were less cohesive. Models that were run with lesser values of cohesion had a greater lateral spread of the deformation region as opposed to those with higher values of cohesion.
Lubecka, Karolina, "The role of subducting plate rheology in outer-rise seismicity: Implications for Japan and South American subduction systems" (2015). Honors Capstone Projects - All. 830.
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