Plate Boundary Models in and around Japan
Takaya IWASAKI
Earthquake Research Institute, the University of Tokyo
iwasaki@eru.u-tokyo.ac.jp

A. Download site：http://evrrss.eri.u-tokyo.ac.jp/database/PLATEmodel/PLMDL_2016/

This site is composed of the following directories.

/Trench/PAC_Plate/Base modelxyz file (ascii)
grid file/contourcontour line files (ascii)/Regional modelxyz file (ascii)
grid file/contourcontour line data (ascii)/PHS Plate/Base modelxyz file (ascii)
grid file/contourcontour line data (ascii)/Regional modelxyz file (ascii)
grid file/contourcontour line data (ascii)

B. Model region：12o-54o N and 118o-164o E (Fig.1)．

C. Trench axis data：

Explanations
Trench axis data are composed of longitude, latitude (degree) and water depth (m).
This data, originally obtained from bathymetry data, were smoothed by spline interpolation(Fig.1)

Directory: /Trench
Filesjapan_trench_pos: Kuril-Japan-Izu-Bonin-Mariana trenchnankai_trough_pos: Sagami-Suruga-Nankai trough-Ryukyu trenchmanila: Manila trench
philippine: Philippine trenchryukyu_taiwan: tectonic boundary from the southernmost ryukyu trench to Taiwan
manila_philippine: tectonic boundary connecting southernmost Manila trench to thenorthernmost Philippine trench.

D. Plate surface dataExplanation(1) Models for Pacific (PAC) plate and Philippine Sea (PHS) plate were prepared.
(Figs.2 and 3)．
(2) Base model
Plate surfaces are determined from earthquake distribution (the Wadati-Benioff zones.
(3) Regional model
Base models around Japan were corrected using results from seismic profiling, seismic
tomography and natural earthquake observation.
(4) Each model provides plate surface positions (longitude, latitude (degree) and depth(km)) with 0.025o grid size. Depth values are taken negative below the sea level.
(5) Grid data in areas where reliable plate surface is not defined are eliminated(for example, PHS plate surface in the Kanto and Chugoku areas).
(6) Both the ascii (~.xyz) and binary (~.grd) data are prepared.

(7) For each plate model, positions of equi-depth line (countour line) are prepared in ascii
format (directory: contour). Users can define their own plate model (subducted part)from these data and trench axis data using an appropriate interpolation technique.

Directory: /PAC_Plate (Pacific plate model)
Base model
directory /base_model
files
pac_2017_3a.xyz
pac_2017_3a.grd
contour line data
directory /contour
files: pac1_cntr_10.bs ~ pac1_cntr_650.bs

Regional model
directory /regional_model
files
pac_2017_4a.xyz
pac_2017_4a.grd
contour line data
directory /contour
files: pac1_cntr_10.rg ~ pac1_cntr_650.rg

Directory: /PHS_Plate (Philippine Sea plate model)
Base model
directory /base_model
filesphs_2015_4a_r_2017xyz
phs_2015_4a_r_2017.grd
contour line data
directory /contour
files: phs1_cntt_10.bs ~ phs1_cntt_300.bs

Regional model
directory /regional_model
files
phs_2015_5a_r_2017.xyz
phs_2015_5a_r_2017.grd
contour line data
directory /contour
files: phs1_cntt_10.rg ~ phs1_cntt_300.rg
E. Topography/Bathymetry data used in our plate models

In constructing our plate model, we used the topography and bathymetry data provided from thefollowing institutes.

(1)

Geospatial Information Authority of Japan (250-m digital map)
(permission No. H29-JoShi-17) .

(2)

Japan Oceanographic Data Center (500m mesh bathymetry data, J-EGG500,,
http://www.jodc.go.jp/jodcweb/JDOSS/infoJEGG_j.html).

(3)

Geographic Information Network of Alaska, University of Alaska (Global
Topo/Bathymetry Grid (Lindquist, et al., 2004, see also “F”).

F. How to refer these plate models(1) If users present/publish their own results, please refer the following references.
Iwasaki, T., Sato, H., Shinohara, M., Ishiyama, T. & Hashima, A., 2015.Fundamental structure modelof island arcs and subducted plates in and around Japan, 2015 Fall Meeting, American
Geophysical Union, San Francisco, Dec. 14-18, T31B-2878.
Lindquist, K. G., K. Engle, D. Stahlke, and E. Price (2004), Global Topography and Bathymetry
Grid Improves Research Efforts, Eos Trans. AGU, 85(19), 186.
http://onlinelibrary.wiley.com/doi/10.1029/2004EO190003/abstract(2) In “Acknowledgement” in users’ presentation/paper, add the following description to make clear
the institutes which provided topography/bathymetry data).

The plate models by Iwasaki et al. (2015) were constructed from topography and bathymetry data

by Geospatial Information Authority of Japan (250-m digital map), Japan Oceanographic Data
Center (500m mesh bathymetry data, J-EGG500,,
http://www.jodc.go.jp/jodcweb/JDOSS/infoJEGG_j.html) and Geographic Information Network ofAlaska, University of Alaska (Lindquist et al., 2004).

Fig.1. Topography and trench-axis models.

Fig.2 Base model and regional model for the PAC plate.

Fig.3 Base model and regional model for the PHS plate.