Earth's crust underneath Japan, Harvard Seismology Group
Name JP
Group Harvard_Seismology
Matrix ID 2757
Num Rows 87,616
Num Cols 67,320
Nonzeros 13,734,559
Pattern Entries 13,734,559
Kind Tomography Problem
Symmetric No
Date 2015
Author P. Bogiatzis, M. Ishii
Editor T. Davis
Structural Rank 26,137
Structural Rank Full false
Num Dmperm Blocks 254
Strongly Connect Components 38,201
Num Explicit Zeros 0
Pattern Symmetry 0%
Numeric Symmetry 0%
Cholesky Candidate no
Positive Definite no
Type real
Download MATLAB Rutherford Boeing Matrix Market
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 http://suitesparse.com.     
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.