Seismic wavefield polarization – Part II: Definition of a parameter system in three-dimensional (3D) space, example case review using LSBB seismic station data

Abstract

Abstract.A full polarization parameter system in 3D space is presented to characterize the state of polarization of a seismic wavefield and to parametrize any type of elliptical polarized seismic wave including extreme linear and circular polarizations. This parameter system does not require the a-priori knowledge of the orientation of the polarization plane and provides access to all parameters required in most polarization studies. Two groups of angular and vectorial parameters are defined, which can be easily related to one another. The knowledge of particle motion polarization opens the field of applications for 3-component seismic records contributing to improvements in phase identification. An example of a time-frequency visualization of the polarization parameters on a teleseimic earthquake recorded at a seismic station of LSBB is presented.

Seismic wavefield polarization – Part I: Describing an elliptical polarized motion, a review of motivations and methods

“…Finally, [5] system must not be mistaken for the convention used in focal mechanism description. A standardized full parameter system is required in seismology (as defined in [6]) to provide a full characterization of any elliptical motion in 3D space including the extreme linear and circular motions and to provide access to all parameters required in most polarization studies.…”

Migration of seismic activity associated with phreatic eruption at Merapi volcano, Indonesia

“…By considering the signal as a superposition of elliptical motions, the idea of Pinnegar (2006) is to directly relate the Fourier spectra (and thus the Stockwell coefficients) to an elliptical motion parameterization. The polarization attributes used in this study to characterize the elliptical motion are ellipticity and orientation of the major displacement calculated through estimation of the trend (azimuth calculated from the North) and a plunge angle, as described in Labonne et al (2016). Note that the Stockwell transform window is a scalable Gaussian window with a frequency range defined as an interval where its standard deviation equals one period length.…”