Harvard_Seismology/JP
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

Notes 
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 Pwave ray paths, from 125
moderate size earthquakes (stars), deeper that ~150 km that occurred
the last decade, and recorded from seismic stations of the Hinet
array (triangles). The 3Dimensional 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 underdetermined 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
http://www.seismology.harvard.edu
Bogiatzis, P., & Ishii, M., 2014. Resolution Analysis and Jointly
Inverted Pand SWave Models of Japan's Crust and Upper Mantle.
American Geophysical Union, Fall Meeting 2014, S33A4501.
