Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 24 for “"Geophones"”.
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Microphone suppression of air-noise on geophones
Air-noise in seismic records creates a loss in signal quality, reducing seismic image clarity. A microphone may be used to estimate and remove air-noise in seismic records. This thesis covers the characterization of air-noise on a prototype 4-Component geophone (3-C geophone plus microphone), as …
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Comparison of 4.5 Hz Geophones and a Broadband Seismometer in a Real Field Deployment
… density and array responses was performed using geophones and broadband seismometers, co-deployed as part of a geologically motivated study. Broadband seismometers record excellent waveforms but, due to cost and deployment effort, wavefields are usually spatially aliased above ~0.1 Hz. Industry …
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Investigating seismicity in Cape Town: implications for active fault lines in the Western Cape, South Africa
… To achieve this, eighteen three-component geophones were deployed across a 40 by 35-kilometre area near the KNPS. The geophones recorded data from August to October 2021 and were located near the Ceres-Tulbagh region, Cape Town, the proposed Milnerton fault, and the Colenso fault zone. …
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Wind Induced Ground Motion
… noise under windy conditions. Multiple triaxial geophones are deployed at different depths to study the wind-induced ground vibrations as a function of depth and wind velocity. Furthermore, a test experiment including a vertical and a horizontal mass-spring apparatus is designed to exert …
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Development of an early warning system for predicting rock bursts and rock induced displacements in seismically active mining blocks at Mufulira underground mine (deeps section).
… that could result in rock bursts. Two geophones have been interconnected in series and connected to the network system via the optical fibre junction box within the seismically active mining blocks to enhance accuracy in picking up rockbursts and rockfalls. Geomechanics properties of …
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A comparison of three seismic methods in the arid environment
… noise tested using a shotgun, high frequency geophones, and an engineering seismograph. The noise spreads were examined for reflection events to determine shotpoint to geophone offset for an optimum window reflection profile. No reflection events were observed in the noise spreads. Trial …
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Modeling the Near-Surface Using High-Resolution Seismic Data
… by using optimally-designed plate-mounded geophones. The two main factors in the design are the plate weight and area. From the experimental data, I conclude that land-streamer data over sand dune can be more coherent than conventional data, especially the first-arrival events.
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Double-Difference Tomography Applied to Monitoring of Geologic Carbon Sequestration in the Aneth Oil Field, Utah
… events were recorded from a borehole array of 22 geophones. Aneth Unit data were divided into four time periods for time-lapse analysis. A low velocity zone spanning the lateral extents of the observable region, likely representing a CO2 plume, is detected when considering voxels containing the …
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A Comparative Case Study of Reflection Seismic Imaging Method
… data was gathered by commid-point method with 60 geophones equally spaced along an about 550 m long traverse over a nearly flat ground. In the future, we will apply different migration algorithms (including finite-difference and Kirchhoff), and the results will be compared in time and depth …
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Body and surface wave ambient noise seismic interferometry across the Salton Sea Geothermal Field, California
… of magnitude below the corner frequency of the geophones, and modest body waves at 22-30 Hz, which are generally more difficult to obtain due to the need for many large, well-distributed subsurface sources. The virtual source gathers compare well to nearby explosive shots and are more densely …
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Microseismic Monitoring of a Room and Pillar Retreat Coal Mine in Southwest Virginia
… behavior (Luxbacher, et al, 2007). An array of geophones was placed underground along a single retreat panel to record failures due to stress redistribution throughout one panel of retreat. These microseismic events were located, and their moment magnitudes were found. An analysis was completed …
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Seismic wave modelling using finite difference methods
… for the source of signals, and also for geophones. One goal of this work was to begin to fill in this gap by including simple borehole configurations within elastic media our new approach modelling, which we have completed successfully.<br/><br/>We investigate the appropriateness of the …
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Identifying shallow subsurface stratigraphy and voids using dispersive characteristics of electromagnetic and surface waves
… for the study. Vertical and horizontal component geophones with different frequencies (14-, and 100-Hz) were employed for this study. The third manuscript presents the results of a study on dispersive electromagnetic signals to identify the thickness and dielectric permittivity of thin soil layers …
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Delineation of a coal combustion residue landfill and underlying karst subsurface in Southwest Missouri using ERT and MASW surveys
… Seistronix engineering seismograph and 4.5 Hz geophones. MASW data were acquired to aid the ERT data interpretation by providing engineering properties of subject materials. The outcome from the ERT survey were a suite of 2D and 3D resistivity images. ERT investigates the subsurface to a depth …
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Subsurface imaging with reverse vertical seismic profiles
… RVSP in 3D with a random distribution of surface geophones is unprecedented. At the time this data was collected, no commercially available processing tools existed to address this geometry, so a processing scheme had to be developed. The data processing sequence presented in this thesis, which …
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The exploitation of acoustic-to-seismic coupling for the determination of soil properties
… has been made from signals received at buried geophones. It has been shown that microphone signals include Type-I P-wave energy in a high flow resistivity soil. Acoustically deduced soil properties are consistent with mechanically derived values. A systematic investigation of outdoor …
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Micro-seismic observations in Leeu Gamka, Karoo, South Africa
… is likely a reporting artefact. An array of 23 geophones was deployed for three months (March - June) in 2015, covering an area of 60 km - 65 km centred on the zone of anomalous seismicity. Using this array, I identified a total of 106 earthquakes over this period, with almost all events …
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Tomographic Imaging Associated with a Mw 2.6 Fault-Slip Event in a Deep Nickel Mine
… distinct events over 62 days. A total of 53 geophones recorded 191,856 p-waves that are able to be used for inversion. Temporal monitoring of the seismic p-wave velocity in the vicinity of a known Mw 2.6 fault-slip event that occurred on March 14th is performed by creating tomograms of the …
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Analysis of Seismic Signatures Generated from Controlled Methane and Coal Dust Explosions in an Underground Mine
… not be controlled for the purposes of the study. Geophones located approximately 600 m (1970 ft) and over from the source collected limited data because of the attenuation of the seismic waves generated by the methane explosion. A combination of the methods used to characterize the seismic …
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Observation and inversion of seismo-acoustic waves in a complex Artic ice environment
… series highlights the dramatic superiority of geophones over hydrophones in this application, as does the ability to detect the anomalous SH waves and the refracted ray paths, neither of which are visible in the hydrophone data. Inversion of the geophone data sets for the low frequency elastic …
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