Open AccessA geometric comparison of source‐type plots for moment tensors
Author(s) -
Tape Walter,
Tape Carl
Publication year - 2012
Publication title -
geophysical journal international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0956-540X
DOI - 10.1111/j.1365-246x.2012.05490.x
Subject(s) - plot (graphics) , cube (algebra) , unit cube , type (biology) , unit sphere , mathematics , context (archaeology) , moment (physics) , eigenvalues and eigenvectors , geometry , mathematical analysis , physics , geology , statistics , classical mechanics , paleontology , quantum mechanics
SUMMARY We describe a general geometric framework for thinking about source‐type plots for moment tensors. We consider two fundamental examples, one where the source‐type plot is on the unit sphere, and one where it is on the unit cube. The plot on the sphere is preferable to the plot on the cube: it is simpler, it embodies a more natural assumption about eigenvalue probabilities and it is more consistent with the conventional Euclidian definition of scalar seismic moment. We describe the source‐type plots of Hudson, Pearce and Rogers in our geometric context, and we find that they are equivalent to a plot on the cube. We therefore suggest the plot on the sphere as an alternative.