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Three-component digital-based seismic landstreamer: Methodologies for infrastructure planning applications
Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.ORCID iD: 0000-0003-4694-9847
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

To support urban infrastructure planning projects, along with various other near-surface applications, a multicomponent landstreamer was developed. The landstreamer was built with broadband (0-800 Hz), three-component (3C) micro-electro-mechanical system (MEMS) sensors. The digital nature of the MEMS sensors makes the developed landstreamer insensitive to electric/electromagnetic noise.

The landstreamer’s design and its seismic imaging capabilities, along with the MEMS technical specifications, were evaluated in several studies. When comparing signals recorded with the streamer with planted MEMS sensors, no negative effects of the design were noted. Compared to different geophones tested, the streamer produced higher quality and broader signal bandwidth data. Additionally, a seismic study conducted in a tunnel demonstrated its electric/electromagnetic noise insensitivity. The streamer combined with wireless seismic recorders was used to survey logistically challenging areas for improved imaging and characterizations and avoid interference with traffic.

For example, at the Stockholm Bypass site, the landstreamer recorded data were used for traveltime tomography with results showing a well delineated bedrock level and potential low-velocity zones matching with inferred poor-quality-class rocks. The seismic response of fractures and their extent between a tunnel and the surface was studied at the Äspö Hard Rock Laboratory site. The velocity model obtained using the traveltime tomography approach showed known well-characterized fracture systems and potential additional formerly unknown ones. Additionally, compressional- and shear-wave velocities, seismic quality factors, Vp/Vs and dynamic Poisson’s ratios of the known fracture zones were obtained. Fractures and/or weakness zones in the bedrock were imaged using refraction and reflection imaging methods at a site contaminated with a cancerogenic pollutant in southwest Sweden, illustrating the potential of the streamer for environmental-related applications. In southern Finland, the landstreamer was used for SH-wave reflection seismic imaging from a vertically oriented impact source with the results showing a well-delineated bedrock level and weak reflections correlating well with geology. At the same site, its potential for multichannel analysis of surface waves (MASW) was demonstrated. The surface-wave obtained shear-wave velocities match well with the borehole based stratigraphy of the site and are complementary to the SH-wave reflectivity and previous investigations at the site.

Studies conducted in this thesis demonstrate the landstreamer’s potential for various near-surface applications and show the benefits and need for 3C seismic data recording. 

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2017. , p. 80
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1610
Keyword [en]
landstreamer, multicomponent seismic, shear-waves, surface-waves
National Category
Geophysics
Research subject
Geophysics with specialization in Solid Earth Physics
Identifiers
URN: urn:nbn:se:uu:diva-335846ISBN: 978-91-513-0186-0 (print)OAI: oai:DiVA.org:uu-335846DiVA, id: diva2:1164138
Public defence
2018-02-02, Hambergsalen, Geocentrum, Villavagen 16, Uppsala, 10:00 (English)
Opponent
Supervisors
Available from: 2018-01-10 Created: 2017-12-10 Last updated: 2018-03-07
List of papers
1. Multicomponent broadband digital-based seismic landstreamer for near-surface applications
Open this publication in new window or tab >>Multicomponent broadband digital-based seismic landstreamer for near-surface applications
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2015 (English)In: Journal of Applied Geophysics, ISSN 0926-9851, E-ISSN 1879-1859, Vol. 123, p. 227-241Article in journal (Refereed) Published
Abstract [en]

During the last few decades there has been an increased demand for infrastructure, along with a greater awareness of environmental issues in the construction industry. These factors have contributed to an increased interest in using seismic methods for near surface characterization, particularly in urban environments. Seismic sensors not affected by anthropogenic electromagnetic noise are therefore important, as well as an acquisition system that is easy to deploy, move and non-invasive. To address some of these challenges, a multicomponent broadband MEMS (micro-electro mechanical system) based landstreamer system was developed. The landstreamer system is fully digital, therefore it is less sensitive to electrical or electromagnetic noise. Crosstalk, leakage and tilting tests show that the system is superior to its predecessors. The broadband nature of the sensors (theoretically 0–800 Hz), 3C (three-component) recording and the close spacing of the sensors enable high-resolution imaging. The current streamer configuration consists of 20 sensors 4 m apart and 80 sensors 2 m apart. The streamer can easily be combined with wireless recorders for simultaneous data acquisition. In this study, we present results from testing of the streamer with various sources, such as a shear wave vibrator and different types of impact sources. MEMS-sensors and their high sensitivity allowed recording clear reflections that were not observed with coil-based sensors. A complementary test was also carried out at a planned access ramp for an urban tunnel where potential poor quality rocks had been identified by drilling. First-break traveltime tomography showed that these poor quality rocks correlate with low velocity zones. The presented landstreamer system has great potential for characterizing the subsurface in noisy environments.

Keyword
Landstreamer, MEMS, Tomography, Near-surface, Urban environment
National Category
Geophysics
Identifiers
urn:nbn:se:uu:diva-267390 (URN)10.1016/j.jappgeo.2015.10.009 (DOI)000366073400022 ()
Funder
Swedish Research Council Formas, 252-2012-1907
Available from: 2015-11-21 Created: 2015-11-21 Last updated: 2017-12-10Bibliographically approved
2. Delineating fracture zones using surface-tunnel-surfaceseismic data, P-S, and S-P mode conversions
Open this publication in new window or tab >>Delineating fracture zones using surface-tunnel-surfaceseismic data, P-S, and S-P mode conversions
2017 (English)In: Journal of Geophysical Research - Solid Earth, ISSN 2169-9313, E-ISSN 2169-9356, Vol. 122, no 7, p. 5493-5516Article in journal (Refereed) Published
Abstract [en]

A surface-tunnel-surface seismic experiment was conducted at the Äspö Hard Rock Laboratoryto study the seismic response of major fracture systems intersecting the tunnel. A newly developedthree-component microelectromechanical sensor-based seismic landstreamer was deployed inside the noisytunnel along with conventional seismic receivers. In addition to these, wireless recorders were placed on thesurface. This combination enabled simultaneous recording of the seismic wavefield both inside the tunneland on the surface. The landstreamer was positioned between two geophone-based line segments, alongthe interval where known fracture systems intersect the tunnel. First arrival tomography produced a velocitymodel of the rock mass between the tunnel and the surface with anomalous low-velocity zones correlatingwell with locations of known fracture systems. Prominent wave mode converted direct and reflected signals,P-S and S-P waves, were observed in numerous source gathers recorded inside the tunnel. Forward traveltime and 2-D finite difference elastic modeling, based on the known geometry of the fracture systems, showthat the converted waves are generated at these systems. Additionally, the landstreamer data were used toestimate Vp/Vs, Poisson’s ratio, and seismic attenuation factors (Qp and Qs) over fracture sets that havedifferent hydraulic conductivities. The low-conductivity fracture sets have greater reductions in P wavevelocities and Poisson’s ratio and are more attenuating than the highly hydraulically conductive fracture set.Our investigations contribute to fracture zone characterization on a scale corresponding to seismicexploration wavelengths.

National Category
Geophysics
Research subject
Geophysics with specialization in Solid Earth Physics
Identifiers
urn:nbn:se:uu:diva-327949 (URN)10.1002/2017JB014304 (DOI)000409366700040 ()
Available from: 2017-08-14 Created: 2017-08-14 Last updated: 2017-12-20Bibliographically approved
3. Multi-component digital-based seismic landstreamer and boat-towed radio-magnetotelluric acquisition systems for improved subsurface characterization in the urban environment
Open this publication in new window or tab >>Multi-component digital-based seismic landstreamer and boat-towed radio-magnetotelluric acquisition systems for improved subsurface characterization in the urban environment
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2017 (English)In: First Break, ISSN 0263-5046, E-ISSN 1365-2397, Vol. 35, no 8, p. 41-47Article in journal (Other academic) Published
Abstract [en]

It is estimated that urban life will be the norm for around 60% of the world’s population by 2040, leading to a more centralized distribution of people and making the city as the main place of residence (Whiteley, 2009). This population centralization inherently implies rapidly expanding cities and imposes the need for more infrastructure within, around and between the present city boundaries. However, infrastructure projects nowadays have to follow strict civil engineering standards that require detailed knowledge of subsurface conditions during different stages of the construction processes. Since direct methods conventionally used for site characterization (e.g., drilling and/or core testing) are still relatively expensive the focus in the last two decades has been on non-invasive, geophysical methods. However, geophysical site characterization in urban areas is not an easy task owing to numerous challenges and various types of noise sources. Challenges such as electric/electromagnetic (EM) noise, pipelines and other subsurface objects (sometimes even unknown or undocumented), the inability to properly couple sensors because of pavement, traffic noises and limited space are common in urban environment. Since geophysical surveys need to be done with the least amount of disturbances to the environment, residents and traffic, new geophysical techniques for fast, non-invasive and high-resolution site characterization are needed. To overcome some of these challenges, a nationwide joint industry-academia project was launched in 2012 TUST GeoInfra, www.trust-geoinfra.se). As a component in the project, Uppsala University developed two new data acquisition systems. These are a fully digital MEMS-based (Micro-machined Electro-Mechanical Sensor) three component (3C) seismic landstreamer and a boat-towed radio-magnetotelluric (RMT) acquisition system. Both systems were specifically designed to address urban environments with the RMT system particularly aiming at efficient and cost-effective geophysical surveying on shallow-water bodies, which constitute 7% of Scandinavia. In this article, we will describe the two systems and present two case studies illustrating their potential. A number of published accounts are now available from the two systems showing what type of problems they can address (e.g., Bastani et al., 2015; Brodic et al., 2015; Malehmir et al., 2015a, 2015b, 2016a, 2016b, 2017; Dehghannejad et al., 2017; Maries et al., 2017; Mehta et al., 2017; Brodic et al., 2017).

Place, publisher, year, edition, pages
Amsterdam, Netherlands: , 2017
National Category
Geophysics
Identifiers
urn:nbn:se:uu:diva-327951 (URN)
Projects
TRUST Geoinfra
Available from: 2017-08-14 Created: 2017-08-14 Last updated: 2017-12-10Bibliographically approved
4. 3C seismic landstreamer study of an esker architecture through shear- and surface-wave imaging
Open this publication in new window or tab >>3C seismic landstreamer study of an esker architecture through shear- and surface-wave imaging
(English)Manuscript (preprint) (Other academic)
Abstract [en]

As a continuation of a seismic experiment to test the capability of a newly developed 3C(three component) MEMS-based (microelectro-mechanical system) seismic landstreamer fordelineating an esker core (porous glacial sediments), depth to water table and bedrock insouthwestern Finland, additional analysis of the same dataset was performed. The seismic sourceused was a 500-kg vertical impact drophammer. We report results from one of the horizontalcomponents of the landstreamer data, the transverse (SH-wave) component. In addition to this,we complement the interpretation conducted previously on P-wave stacked section with surfacewavederived shear-wave velocities and Vp/Vs ratios along the entire profile.Although the seismic source used is of vertical-type nature, peculiarly, the data inspectionshowed clear bedrock reflection on the SH-wave component. This observation led us toscrutinize the transverse component data through side-by-side inspection of the shot records onall the three components and particle motion (hodograms) analysis to confirm the pure shearnature of the reflection. Using the apparent moveout velocity of the reflection, as well as knowndepth to bedrock based on drilling, we employed finite-difference synthetic modelling to furtherverify the nature of the reflection. Compared to the P-wave seismic section, bedrock is moreaccurately delineated on the SH-wave section. Some structures connected to the MUKH(morphologically undetectable kettle hole) imaged on the P-wave results are also notable on theSH-wave section, and particularly on the surface-wave derived shear-wave velocity model. Ourresults indicate that the SH-wave energy is generated at the source location itself. This study isencouraging and illustrates why multicomponent seismic data should be acquired and analyzedfor near-surface applications.

Keyword
landstreamer, shear-waves, surface-waves, MASW
National Category
Geophysics
Research subject
Geophysics with specialization in Solid Earth Physics
Identifiers
urn:nbn:se:uu:diva-335429 (URN)
Available from: 2017-12-05 Created: 2017-12-05 Last updated: 2017-12-10

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CiteExportLink to record
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Citation style
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Output format
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