Matrix: Harvard_Seismology/JP

Description: Earth's crust underneath Japan, Harvard Seismology Group

Harvard_Seismology/JP graph
(bipartite graph drawing)

Harvard_Seismology/JP dmperm of Harvard_Seismology/JP
scc of Harvard_Seismology/JP

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  • download as a MATLAB mat-file, file size: 122 MB. Use UFget(2757) or UFget('Harvard_Seismology/JP') in MATLAB.
  • download in Matrix Market format, file size: 165 MB.
  • download in Rutherford/Boeing format, file size: 156 MB.

    Matrix properties
    number of rows87,616
    number of columns67,320
    structural full rank?no
    structural rank26,137
    # of blocks from dmperm254
    # strongly connected comp.38,201
    explicit zero entries0
    nonzero pattern symmetry 0%
    numeric value symmetry 0%
    Cholesky candidate?no
    positive definite?no

    authorP. Bogiatzis, M. Ishii
    editorT. Davis
    kindtomography problem
    2D/3D problem?no


    Earth's crust underneath Japan, Harvard Seismology Group.               
    This matrix represents the forward operator of a linearized seismic     
    tomography problem for imaging Japan's crust and upper mantle.  The     
    rows of the matrix correspond to 87,616 P-wave ray paths, from 125      
    moderate size earthquakes (stars), deeper that ~150 km that occurred    
    the last decade, and recorded from seismic stations of the Hi-net       
    array (triangles). The 3-Dimensional space is parameterized using a     
    grid of 67,320 parameters that correspond to the columns of the matrix. 
    The matrix is structurally and numerically rank deficient.  This is     
    because some parts of the Earth are not imaged well from the data,      
    due to the lack of signals (earthquakes) and receivers (seismic stations
    in those areas.  This leads to an under-determined part of the system.  
    Other parts of the problem are overdetermined, because deep earthquakes 
    repeat in the same region of the Earth, over time, and the seismic      
    stations do not move.  Repeated earthquakes from the same source        
    are recorded by the same seismic stations, leading to an over-          
    determined problem for those regions of the Earth.                      
    In MATLAB, cs_dmspy(Problem.A) displays these two parts of the matrix,  
    using a function from CSparse, available at     
    Petros Bogiatzis, Miaki Ishii, Harvard Seismology Group, 2015                                             
    Bogiatzis, P., & Ishii, M., 2014. Resolution Analysis and Jointly       
    Inverted P-and S-Wave Models of Japan's Crust and Upper Mantle.         
    American Geophysical Union, Fall Meeting 2014, S33A-4501.               

    For a description of the statistics displayed above, click here.

    Maintained by Tim Davis, last updated 15-Jul-2015.
    Matrix pictures by cspy, a MATLAB function in the CSparse package.
    Matrix graphs by Yifan Hu, AT&T Labs Visualization Group.