Work Description

Title: The enhancement of coseismic slip and ground motion due to the accretionary wedge and sedimentary layer in the 2011 Tohoku-Oki earthquake [Data] Open Access Deposited

http://creativecommons.org/licenses/by-nc/4.0/
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Description
  • Low-velocity accretionary wedges and sedimentary layers overlaying continental plates are widely observed in the subduction zones where historical large earthquakes have occurred. It was observed that rupture of the 2011 Mw 9.0 Tohoku-Oki earthquake propagated to the trench with large coseismic slip on the shallow fault, but what caused the huge shallow slip remains a prominent problem.

  • Here we explore how the two low-velocity structures, accretionary wedge and sedimentary layer, affect the coseismic slip and near-fault ground motions during the 2011 Tohoku-Oki earthquake. Constrained by the observed seafloor deformation, we present a 2-D dynamic rupture model of the 2011 Tohoku-Oki earthquake with an accretionary wedge and a sedimentary layer. Compared to a homogeneous model with the same friction and stress parameters on the fault, we find that the co-existence of the accretionary wedge and sedimentary layer significantly enhances the shallow coseismic slip and amplifies ground accelerations near the accretionary wedge. We then investigate a plausible scenario of a smaller Tohoku-Oki earthquake when its rupture does not reach the accretionary wedge. The sedimentary layer slightly enhances the coseismic slip while the accretionary wedge has almost no influence for the smaller earthquake scenario, but both structures significantly amplify the ground accelerations on the overriding plate.

  • By simulating a suite of earthquake scenarios, we suggest that the co-existence of an accretionary wedge and sedimentary layers tend to enhance coseismic slip, but the enhancement effect decreases as the up-dip limit of rupture zones terminates at a larger depth. The numerical simulations were solved using SEM2DPACK _2.3.8 ( http://www.sourceforge.net/projects/sem2d/), and simulation results were visualized by Matlab. This folder includes the input files to reproduce our simulation results and plot scripts.
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  • lilixian@umich.edu
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  • Other Funding Agency
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  • China Scholarship Council
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Last modified
  • 02/25/2021
Published
  • 02/25/2021
DOI
  • https://doi.org/10.7302/rerb-bd58
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To Cite this Work:
Xian Li. The enhancement of coseismic slip and ground motion due to the accretionary wedge and sedimentary layer in the 2011 Tohoku-Oki earthquake [Data] [Data set], (2021). University of Michigan - Deep Blue. https://doi.org/10.7302/rerb-bd58

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Files (Count: 3; Size: 23.2 MB)

Creator: Xian Li, Feb 22, 2021

To Cite this Work:

Xian Li. The enhancement of coseismic slip and ground motion due to the accretionary wedge and sedimentary layer in the 2011 Tohoku-Oki earthquake [Data set]. University of Michigan - Deep Blue. https://doi.org/10.7302/rerb-bd58

Notations of folder/file name:

EQ: earthquake
awsed: model with accretionary wedge and sedimentary.
awonly: model only with accretionary wedge.
sedonly: model only with sedimentary layer.
homo: homogeneous model.

Files contained:

The folder named 'input_files' contains three kinds of files: '.inp', '.mesh2d', '.txt'.
- '.inp' files set parameters for models, including material velocities, densities, normal stress, friction coefficients, initial shear stress on faults et al. Details about the blocks in '.inp' files are described in the manual of SEM2DPACK (http://web.gps.caltech.edu/~ampuero/soft/users_guide_sem2dpack.pdf). Note that the input file must be called Par.inp when you run simulations in SEM2DPACK.
- '.mesh2d' files store mesh information of models, which are imported by '.inp' files in the block &MESH_MESH2D.
- '.txt' files are location data of receivers, which are imported by '.inp' files in the block &REC_LINE.

Under the folder named '2011Tohoku_EQ', the 'comparisons' folder store the input files of awsed, awonly, sedonly, homo models, which have the same friction and stress state on the fault.
The 'bestfitting_models' folder store the input files which produce deformation best-fitting observation for the awonly, sedonly, homo models.
The 'smaller_EQ' folder store the input files of awsed, awonly, sedonly, homo models, which have the same friction and stress state on the fault. The four models generate small earthquakes whose rupture does not reach the accretionary wedge.
The 'otherEQ_scenarios' folder includes four other earthquake scenarios when the rupture terminates at different depths.

The folder named 'plot_scripts' contains '.m' files which are used for visualization by Matlab.
- 'figure2.m' plots the surface projection of the along-dip distributions of initial shear stress, static strength, dynamic strength , and critical slip distance for the 2011 Tohoku-Oki earthquake and a smaller Tohoku-Oki earthquake.
- 'figure3.m' plots the surface deformation, fault slip, and slip rate produced by the awsed, awonly, sedonly, homo models during the 2011 Tohoku-Oki earthquake.
- 'figure4.m' plots increased fault slip and surface deformation in the non-homogeneous models compared with the homogeneous model in the 2011 Tohoku-Oki earthquake.
- 'figure5.m' plots fault slip and surface ∂deformation produced by the awsed, awonly, sedonly, homo models during the smaller Tohoku-Oki earthquake.
- 'figure6.m' compares accelerograms between the awsed and homogeneous models, and compares amplification factors for two frequency ranges at 0.1-0.5 Hz and 0.5-2.0 Hz produced by the three non-homogeneous models.

How to use these data:
1. Download SEM2DPACK version 2.3.8 from http://www.sourceforge.net/projects/sem2d
2. Compiling the solver code following the user's guide: http://web.gps.caltech.edu/~ampuero/soft/users_guide_sem2dpack.pdf
3. Put the input file '.inp' into the folder 'SEM2DPCAK', and change the name to 'Par.inp'.
4. Run simulations by the command ./sem2dslove.
5. Get result folders.
6. Give paths of these result folders in '.m' files, and plot simulation data.

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