why are azimuths limited to 0 to 180 deg? I’m confused on whats going on here, and assumed I’m not understanding something. I’m plotting particle motion azimuths for an event in the center of an array, but since the azimuths wont cross 180, the particle motion looks incorrect (e.g. not radial).

E.g. I expect my NW station to have an azimuth of 135 degree, and my SE station to have an azimuth of the 315 (assuming these azimuths are CW from north).


Dear Andre,

the estimation of the azimuth has a 180 deg ambiguity. What is done in the Flinn algorithm (covariance and SVD) is simply fitting a rotational ellipsoid to the particle motion data. By definition it is not clear which incidence angle (compression or dilatation for P or SV or SH) the ray is taking. Thus without knowing the quadrant of an earthquakes radiation pattern or the wave type you are looking at it is not possible to solve this. Same is true for odr based techniques...
So if you have extra knowledge you need to include this 'by hand' and correct for this.

Best Joachim