Analysis of Rayleigh waves with circular wavefront: a maximum likelihood approach
Open access
Date
2017-09Type
- Journal Article
Abstract
Analysis of Rayleigh waves is an important task in seismology and geotechnical investigations. In fact, properties of Rayleigh waves such as velocity and polarization are important observables that carry information about the structure of the subsoil. Applications analysing Rayleigh waves include active and passive seismic surveys. In active surveys, there is a controlled source of seismic energy and the sensors are typically placed near the source. In passive surveys, there is not a controlled source, rather, seismic waves from ambient vibrations are analysed and the sources are assumed to be far outside the array, simplifying the analysis by the assumption of plane waves. Whenever the source is in the proximity of the array of sensors or even within the array it is necessary to model the wave propagation accounting for the circular wavefront. In addition, it is also necessary to model the amplitude decay due to geometrical spreading. This is the case of active seismic surveys in which sensors are located near the seismic source. In this work, we propose a maximum likelihood (ML) approach for the analysis of Rayleigh waves generated at a near source. Our statistical model accounts for the curvature of the wavefront and amplitude decay due to geometrical spreading. Using our method, we show applications on real data of the retrieval of Rayleigh wave dispersion and ellipticity. We employ arrays with arbitrary geometry. Furthermore, we show how it is possible to combine active and passive surveys. This enables us to enlarge the analysable frequency range and therefore the depths investigated. We retrieve properties of Rayleigh waves from both active and passive surveys and show the excellent agreement of the results from the two surveys. In our approach we use the same array of sensors for both the passive and the active survey. This greatly simplifies the logistics necessary to perform a survey. Show more
Permanent link
https://doi.org/10.3929/ethz-b-000237941Publication status
publishedExternal links
Journal / series
Geophysical Journal InternationalVolume
Pages / Article No.
Publisher
Oxford University PressSubject
Time-series analysis; Site effects; Surface waves and free oscillationsOrganisational unit
02818 - Schweiz. Erdbebendienst (SED) / Swiss Seismological Service (SED)
Notes
It was possible to publish this article open access thanks to a Swiss National Licence with the publisher.More
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