focalmech(fm, centerX, centerY, diam, varargin)

Draw a full moment tensor focal mechanism for an earthquake
Updated 10 Sep 2019

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Function takes 3x3 or vector of 6 independent elements of a moment tensor and plots the appropriate beachball for that earthquake
% Ryukyu Islands earthquake 4/18/2008 (from
M = [4.070 -1.830 -2.240 1.500 1.410 -1.110];
Mw = 5.0;
axis equal
% Mt. Carmel aftershock 4/18/2008
M = [ -0.754 2.250 -1.490 -0.435 -0.094 0.730 ];
Mw = 4.6;

Cite As

James Conder (2024). focalmech(fm, centerX, centerY, diam, varargin) (, MATLAB Central File Exchange. Retrieved .

MATLAB Release Compatibility
Created with R2019a
Compatible with any release
Platform Compatibility
Windows macOS Linux

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Version Published Release Notes

Added option for moment tensor to be in xyz coordinate system (default still rtf).

... and another.
Just updated the comments to include page numbers and volume of the manuscript this was published in. No changes to the code itself.

Another minor tweak for efficiency.

Improved speed by vectorizing main loop. Runs 4-10x faster than previous version.

Added optional input for text above beachball. E.g.,
>> focalmech(M,5.2,0, Mw,'text','4/18/2008')

Fix a plotting issue that arose when matlab breaks a single contour into multiple pieces.

Fixed bug that sometimes reversed color pattern for events with >40% isotropic components.

Rewrote the portion to fill the beachballs that should behave for older versions as well as the current version of MatLab (Grzegorz's comment).