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Exploring the model space and ranking a best class of models in surface-wave dispersion inversion; application at European strong-motion sites

Giuseppe Di Giulio, Alexandros Savvaidis, Matthias Ohrnberger, Marc Wathelet, Cecile Cornou, Brigitte Knapmeyer-Endrun, Florence Renalier, Nikos Theodoulidis and Pierre-Yves Bard
Exploring the model space and ranking a best class of models in surface-wave dispersion inversion; application at European strong-motion sites
Geophysics (May 2012) 77 (3): B147-B166

Abstract

The inversion of surface-wave dispersion curve to derive shear-wave velocity profile is a very delicate process dealing with a nonunique problem, which is strongly dependent on the model space parameterization. When independent and reliable information is not available, the selection of most representative models within the ensemble produced by the inversion is often difficult. We implemented a strategy in the inversion of dispersion curves able to investigate the influence of the parameterization of the model space and to select a "best" class of models. We analyzed surface-wave dispersion curves measured at 14 European strong-motion sites within the NERIES EC-Project. We focused on the inversion task exploring the model space by means of four distinct parameterization classes composed of layers progressively added over a half-space. The classes differ in the definition of the shear-wave velocity profile; we considered models with uniform velocity as well as models with increasing velocity with depth. At each site and for each model parameterization, we performed an extensive surface-wave inversion (200,100 models for five seeds) using the conditional neighborhood algorithm. We addressed the model evaluation following the corrected Akaike's information criterion (AICc) that combines the concept of misfit to the number of degrees of freedom of the system. The misfit was computed as least-squares estimation between theoretical and observed dispersion curve. The model complexity was accounted in a penalty term by AICc. By applying such inversion strategy on 14 strong-motion sites, we found that the best parameterization of the model space is mostly three to four layers over a half-space; where the shear-wave velocity of the uppermost layers can follow uniform or power-law dependence with depth. The shear-wave velocity profiles derived by inversion agree with shear-wave velocity profiles provided by borehole surveys at approximately 80% of the sites.


ISSN: 0016-8033
EISSN: 1942-2156
Coden: GPYSA7
Serial Title: Geophysics
Serial Volume: 77
Serial Issue: 3
Title: Exploring the model space and ranking a best class of models in surface-wave dispersion inversion; application at European strong-motion sites
Affiliation: Istituto Nazionale di Geofisica e Vulcanologia, Rome, Italy
Pages: B147-B166
Published: 20120501
Text Language: English
Publisher: Society of Exploration Geophysicists, Tulsa, OK, United States
References: 111
Accession Number: 2012-076988
Categories: Seismology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: Includes appendices
Illustration Description: illus. incl. 2 tables
N36°30'00" - N47°30'00", E06°30'00" - E19°00'00"
Secondary Affiliation: Institute of Engineering Seismology and Earthquake Engineering, GRC, GreeceUniversity of Potsdam, DEU, GermanyUniversite Joseph Fourier, FRA, France
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by Society of Exploration Geophysicists, Tulsa, OK, United States
Update Code: 201240
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