Inversion of Seismic Surface Wave Data to Resolve Complex Profiles

Luke, Barbara; Calderón‐Macías, Carlos

doi:10.1061/(asce)1090-0241(2007)133:2(155)

Cited by 28 publications

(16 citation statements)

References 17 publications

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“…In order to reduce the non‐uniqueness of the inversion, the borehole and other geophysical information are used to estimate the depth to bedrock and a Poisson’s ratio

(ν)

of 0.4 was used for all soil layers and

ν = 0.25

was used for bedrock layers. Following the recommendations of Cercato () and Luke and Calderón‐Macías () the layer thickness in the model was increased exponentially with depth. This reflects the fact that the resolving power of MASW data decreases with depth.…”

Section: Geophysical Resultsmentioning

confidence: 99%

Geophysical and geotechnical assessment of a railway embankment failure

Donohue

Gavin

Tolooiyan

2010

Near Surface Geophysics

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A geophysical investigation was carried out after the failure of an important railway embankment in the south-east of Ireland. The embankment, which had a long-term history of stability problems, was studied using a combination of ground-penetrating radar (GPR), electrical resistivity tomography (ERT), multichannel analysis of surface waves (MASW) and geotechnical testing. A significant thickening of the ballast layer around the failure location was observed using GPR, which confirmed the existence of an ongoing stability problem in the area. ERT profiles determined the presence and spatial extent of a significant layer of soft clay both beneath and to the east of the embankment, which could have a major impact on its long-term stability. ERT also detected steeply sloping bedrock close to the failure zone that is likely to have contributed to the long-term settlement of the embankment, which necessitated frequent re-ballasting. MASW confirmed the presence of the steeply sloping bedrock in addition to determining the low stiffness (G max ) values of the embankment fill.High quality sampling of the soft clay deposit was undertaken and strength and compressibility tests revealed the importance of this layer to both the on-going serviceability problems evident for the original embankment and the stability problems encountered by the remodelled section.

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“…In order to reduce the non‐uniqueness of the inversion, the borehole and other geophysical information are used to estimate the depth to bedrock and a Poisson’s ratio

(ν)

of 0.4 was used for all soil layers and

ν = 0.25

Section: Geophysical Resultsmentioning

confidence: 99%

Geophysical and geotechnical assessment of a railway embankment failure

Donohue

Gavin

Tolooiyan

2010

Near Surface Geophysics

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“…An alternative approach is the linearized inversion, which has been extensively applied using least squares methods [e.g., Wiggins , ; Nolet , ; Gabriels et al , ; Xia et al , ; Herrmann , ]. Luke and Calderon‐Macías [] showed that linearized inversion yields excellent dispersion results for well‐constrained S wave velocity profiles. To determine the S wave velocity structure of the firn and underlying ice from the surface wave velocities, we applied the linearized inversion code suggested by Herrmann [].…”

Section: Methodsmentioning

confidence: 99%

Anisotropy and crystalline fabric of Whillans Ice Stream (West Antarctica) inferred from multicomponent seismic data

et al. 2015

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Crystal orientation fabric (COF) describes the intrinsic anisotropic nature of ice and is an important parameter for modeling glacier flow. We present the results of three‐component active‐source seismic observations from the Whillans Ice Stream (WIS), a fast‐flowing ice stream in West Antarctica. Surface‐wave dispersion analysis, ray tracing, and traveltime inversion of compressional (P) and shear (S) waves reveal the presence of transversely isotropic ice with a vertical axis of symmetry (VTI) beneath approximately 65 m of isotropic firn. The ice stream is characterized by weak anisotropy, involving an average ice thickness of approximately 780 m. The analysis indicates that about 95% of the ice mass is anisotropic, and the crystalline c axes span within an average broad cone angle of 73 ± 10° with respect to the vertical axis. Moreover, the mean temperature T (below the firn) estimated from seismic data is −15 ± 5°C. These data do not show evidence of englacial seismic reflectivity, which indicates the lack of abrupt changes in the COF. The presence of azimuthal anisotropy due to transversely compressive flow or fractures aligned along a preferential direction is also excluded. We suggest that the observed VTI ice structure is typical of large ice streams in regions where basal sliding and bed deformation dominate over internal glacial deformation.

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“…In order to reduce the non‐uniqueness of the inversion, P‐wave velocities from the seismic refraction surveys were included as a priori information. Following the recommendations of Cercato () and Luke and Calderón‐Macías () the layer thickness in the model was increased exponentially with depth. This reflects the fact that the resolving power of MASW data decreases with depth.…”

Section: Geophysical Acquisition Parametersmentioning

confidence: 99%

Multi‐method geophysical mapping of quick clay

Donohue

Long

O’Connor³

et al. 2012

Near Surface Geophysics

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The UCD community has made this article openly available. Please share how this access benefits you. Your story matters! (@ucd_oa) Some rights reserved. For more information, please see the item record link above. ABSTRACT Marine clay deposits in coastal, post-submarine areas of Scandinavia and North America may be subjected to quick clay landslides and hence significant efforts are being taken to map their occurrence and extent. The purpose of this paper is to assess the use of a number of geophysical techniques for identifying quick clay. The investigated area, Smørgrav, located in southern Norway has a history of quick clay sliding, the most recent event occurring in 1984. Geophysical techniques that are used include electromagnetic conductivity mapping, electrical resistivity tomography, seismic refraction and multichannel analysis of surface waves. These results are compared to geotechnical data from bore samples, rotary pressure soundings and cone penetration testing. A number of these approaches have proved promising for identifying quick clay, in particular electrical resistivity tomography and electromagnetics, which delineated a zone of quick clay that had previously been confirmed by rotary pressure soundings and sampling. Seismic refraction was useful for determining the sediment distribution as well as for indicating the presence of shallow bedrock whereas the multichannel analysis of surface-waves approach suggested differences between the intact stiffness of quick and unleached clay. It is observed that quick clay investigations using discrete rotary pressure soundings can be significantly enhanced by using, in particular, electrical resistivity tomography profiles to link together the information between test locations, perhaps significantly reducing the need for large numbers of soundings.

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Inversion of Seismic Surface Wave Data to Resolve Complex Profiles

Cited by 28 publications

References 17 publications

Geophysical and geotechnical assessment of a railway embankment failure

Geophysical and geotechnical assessment of a railway embankment failure

Anisotropy and crystalline fabric of Whillans Ice Stream (West Antarctica) inferred from multicomponent seismic data

Multi‐method geophysical mapping of quick clay

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