Rayleigh wave dispersion curves from array-derived rotation and translational data = Curvas de dispersión de ondas Rayleigh por movimientos de rotación obtenidos de un arreglo de sensores y data de translación
The ambient noise analysis field has several methods used to study Microzonation with the aim to mitigate the risk of damage in structures. A new method to study seismic noise was developed by Wassermann et al., 2016. The novel technique uses the existent relation between the transverse component of acceleration and the vertical component of rotation generated by Love waves to retrieve their inherent dispersive character (Kurrle et al., 2010). The advantage of this implementation is that it only needs two instruments to measure acceleration and rotation in the same location, making it easy to deploy as the H/V spectral ratio. Moreover, the information retrieved is easier to interpret than the aforementioned technique. In addition, the same aspects of the wavefield retrieved from array echniques such as F-K and SPAC could be recovered. This thesis aims to complement this method by studying Rayleigh waves and using the implicit relation between the vertical acceleration and the horizontal rotation or tilt generated by them. We use a statistical process to build dispersion curves for this kind of wave, finding its phase velocities in the medium and its arrival direction. Our findings indicated that the new implementation overestimates the phase velocities, which may be due to the fact that a weak-rotational motion sensor was not available, and the array-derived rotation method was used. Hence, this led to high uncertainties in the measure of rotation and also to lower magnitudes of its horizontal components with respect to the vertical one. The method seems reliable to find the back azimuth of noise generated by Rayleigh waves and complements well the findings of the Love-wave technique previously mentioned.
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