The rotate2D() function rotates the two horizontal components of a
seismic signal into Radial and Transverse components returned as a list of 2 Stream objects.
rotate2D(st1, st2, angle)A list of two Stream objects stR and stT is returned.
horizontal Stream from a channel set (channel name usually ending in "N", "E", "1", or "2")
horizontal Stream from a channel set, complementary to st1
angle (degrees) of the rotation
Jonathan Callahan jonathan@mazamascience.com
The rotation web service returns Radial and Transverse seismic Streams, generated by
rotating st1 and st2 by angle degrees.
The rotation service uses the following transformation matrix to change the output vectors for 2-D horizontal transformations
$$ M_{2D} = \left[ \begin{array}{cc} cos \alpha & sin \alpha \cr -sin \alpha & cos \alpha \end{array} \right] $$
$$ \left[ \begin{array}{c} R \cr T \end{array} \right] = M_{2D} \left[ \begin{array}{c} N \cr E \end{array} \right] $$
where :
N and E represent data from the original (horizontal) orientations.
R and T represent the Radial and Transverse components.
\eqn{\alpha} is the azimuth angle measured clockwise from north.
IRIS DMC rotation web service: