Observations And Modeling Of Rotational Signals In The P-Coda: Constraints On Crustal Scattering
Abstract
In addition to three classical components (vertical, N-S, and E-W) of ground translations recorded by broadband seismometer, a component of earthquake induced rotational ground motions around the vertical axis is consistently measured by a ring laser sensor located in Wettzell, SE Germany. Significant rotations around the vertical axis in the P coda of tele-seismic signals are either directly visible or can be inferred through the investigation of cross-correlation between transverse component of translation acceleration and ring laser rotation rate. Theoretically, in spherically symmetric isotropic media we should not observe rotational signals around the vertical axis before the onset of SH waves. Possible explanations for the observed rotations in the P coda are: (1) tilt - ring laser coupling; (2) anisotropy; (3) topographic scattering; and (4) P-SH scattering in the crust. Here we show that P-SH scattering in the 3D random crust is the main cause of the observations and allow us to constrain crustal scattering properties.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2008
- Bibcode:
- 2008AGUFM.S43B1884P
- Keywords:
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- 4255 Numerical modeling (0545;
- 0560);
- 6982 Tomography and imaging (7270;
- 8180)