Effects of near-surface waveguides on shallow high-resolution seismic refraction and reflection data

1996 ◽  
Vol 23 (5) ◽  
pp. 495-498 ◽  
Author(s):  
J. O. A. Robertsson ◽  
K. Holliger ◽  
A. G. Green ◽  
A. Pugin ◽  
R. De Iaco
Keyword(s):  
High Resolution ◽  
Seismic Refraction ◽  
Near Surface ◽  
Reflection Data

scholarly journals Geophysical investigations for stability and safety mitigation of regional crude-oil pipeline near abandoned coal mines

2021 ◽  
Vol 18 (1) ◽  
pp. 145-162
Author(s):  
B Butchibabu ◽  
Prosanta Kumar Khan ◽  
P C Jha
Keyword(s):  
High Resolution ◽  
Crude Oil ◽  
Seismic Refraction ◽  
High Resolution Imaging ◽  
Weak Zone ◽  
Near Surface ◽  
Oil Pipeline ◽  
Refraction Tomography ◽  
Geophysical Investigations ◽  
Resolution Imaging

Abstract This study aims for the protection of a crude-oil pipeline, buried at a shallow depth, against a probable environmental hazard and pilferage. Both surface and borehole geophysical techniques such as electrical resistivity tomography (ERT), ground penetrating radar (GPR), surface seismic refraction tomography (SRT), cross-hole seismic tomography (CST) and cross-hole seismic profiling (CSP) were used to map the vulnerable zones. Data were acquired using ERT, GPR and SRT along the pipeline for a length of 750 m, and across the pipeline for a length of 4096 m (over 16 profiles of ERT and SRT with a separation of 50 m) for high-resolution imaging of the near-surface features. Borehole techniques, based on six CSP and three CST, were carried out at potentially vulnerable locations up to a depth of 30 m to complement the surface mapping with high-resolution imaging of deeper features. The ERT results revealed the presence of voids or cavities below the pipeline. A major weak zone was identified at the central part of the study area extending significantly deep into the subsurface. CSP and CST results also confirmed the presence of weak zones below the pipeline. The integrated geophysical investigations helped to detect the old workings and a deformation zone in the overburden. These features near the pipeline produced instability leading to deformation in the overburden, and led to subsidence in close vicinity of the concerned area. The area for imminent subsidence, proposed based on the results of the present comprehensive geophysical investigations, was found critical for the pipeline.

Surface Seismic Measurements of Near-Surface P- and S-Wave Seismic Velocities at Earthquake Recording Stations, Seattle, Washington

1999 ◽  
Vol 15 (3) ◽  
pp. 565-584 ◽  
Author(s):  
Robert A. Williams ◽  
William J. Stephenson ◽  
Arthur D. Frankel ◽  
Jack K. Odum
Keyword(s):  
Seismic Refraction ◽  
Ground Surface ◽  
Industrial Area ◽  
High Amplitude ◽  
Seismic Velocities ◽  
S Wave ◽  
Near Surface ◽  
Sedimentary Deposits ◽  
Reflection Data ◽  
Seismic Reflections

We measured P- and S-wave seismic velocities to about 40-m depth using seismic-refraction/reflection data on the ground surface at 13 sites in the Seattle, Washington, urban area, where portable digital seismographs recently recorded earthquakes. Sites with the lowest measured Vs correlate with highest ground motion amplification. These sites, such as at Harbor Island and in the Duwamish River industrial area (DRIA) south of the Kingdome, have an average Vs in the upper 30 m (V¯s30) of 150 to 170 m/s. These values of V¯s30 place these sites in soil profile type E (V¯s30 < 180 m/s). A “rock” site, located at Seward Park on Tertiary sedimentary deposits, has a V¯s30 of 433 m/s, which is soil type C (V¯s30: 360 to 760 m/s). The Seward Park site V¯s30 is about equal to, or up to 200 m/s slower than sites that were located on till or glacial outwash. High-amplitude P- and S-wave seismic reflections at several locations appear to correspond to strong resonances observed in earthquake spectra. An S-wave reflector at the Kingdome at about 17 to 22 m depth probably causes strong 2-Hz resonance that is observed in the earthquake data near the Kingdome.

Near‐surface seismic reflection profiling of the Matanuska Glacier, Alaska

Geophysics ◽  
2003 ◽  
Vol 68 (1) ◽  
pp. 147-156 ◽  
Author(s):  
Gregory S. Baker ◽  
Jeffrey C. Strasser ◽  
Edward B. Evenson ◽  
Daniel E. Lawson ◽  
Kendra Pyke ◽  
...  
Keyword(s):  
High Resolution ◽  
Seismic Reflection ◽  
Longitudinal Axis ◽  
Horizontal Distribution ◽  
P Wave ◽  
Near Surface ◽  
Surface Reflection ◽  
Reflection Data ◽  
Basal Ice ◽  
Matanuska Glacier

Several common‐midpoint seismic reflection profiles collected on the Matanuska Glacier, Alaska, clearly demonstrate the feasibility of collecting high‐quality, high‐resolution near‐surface reflection data on a temperate glacier. The results indicate that high‐resolution seismic reflection can be used to accurately determine the thickness and horizontal distribution of debris‐rich ice at the base of the glacier. The basal ice thickens about 30% over a 300‐m distance as the glacier flows out of an overdeepening. The reflection events ranged from 80‐ to 140‐m depth along the longitudinal axis of the glacier. The dominant reflection is from the contact between clean, englacial ice and the underlying debris‐rich basal ice, but a strong characteristic reflection is also observed from the base of the debris‐rich ice (bottom of the glacier). The P‐wave propagation velocity at the surface and throughout the englacial ice is 3600 m/s, and the frequency content of the reflections is in excess of 800 Hz. Supporting drilling data indicate that depth estimates are correct to within ± 1 m.

scholarly journals Application of high resolution geophysical prospecting to assess the risk related to subsurface deformationin Mexico City

2015 ◽  
Vol 372 ◽  
pp. 267-272 ◽  
Author(s):  
F. A. Centeno-Salas ◽  
D. Carreón-Freyre ◽  
W. A. Flores-García ◽  
R. I. Gutiérrez-Calderón
Keyword(s):  
High Resolution ◽  
Mexico City ◽  
Ground Deformation ◽  
Poisson Ratio ◽  
Accurate Determination ◽  
Seismic Refraction ◽  
Geophysical Prospecting ◽  
Seismic Profiles ◽  
Near Surface ◽  
S Waves

Abstract. In the eastern sector of Mexico City the sub soil consists of high contrasting sequences (lacustrine and volcanic inter bedded deposits) that favor the development of erratic fracturing in the surface causing damage to the urban infrastructure. The high-resolution geophysical prospecting are useful tools for the assessment of ground deformation and fracturing associated with land subsidence phenomena. The GPR method allowed to evaluate the fracture propagation and deformation of vulcano-sedimentary sequences at different depths, the main electrical parameters are directly related with the gravimetric and volumetric water content and therefore with the plasticity of the near surface prospected sequences. The active seismology prospection consisted in a combination of Seismic Refraction (SR) and Multichannel Analysis of Surface Waves (MASW) for the estimation of the velocity of the mechanical compressive (P) and the shear (S) waves. The integration of both methods allowed to estimate the geomechanical parameters characterizing the studied sequence, the Poisson Ratio and the volumetric compressibility. The obtained mechanical parameters were correlated with laboratory measured parameters such as plasticity index, density, shear strength and compressibility and, GPR and seismic profiles were correlated with the mapped fracture systems in the study area. Once calibrated, the profiles allowed to identify the lithological contact between lacustrine and volcanic sequences, their variations of thicknesses in depth and to assess the deformation area in the surface. An accurate determination of the geometry of fracturing was of the most importance for the assessment of the geological risk in the study area.

Detection of seismic refraction signals using a variance fractal dimension technique

Geophysics ◽  
2000 ◽  
Vol 65 (1) ◽  
pp. 286-292 ◽  
Author(s):  
Lingxiu Jiao ◽  
Wooil M. Moon
Keyword(s):  
Fractal Dimension ◽  
High Resolution ◽  
Seismic Reflection ◽  
Seismic Refraction ◽  
Window Size ◽  
Real Data ◽  
Seismic Signals ◽  
Seismic Reflection Data ◽  
Reflection Seismic ◽  
Reflection Data

Seismic signals in deep crustal surveys are often contaminated with various types of noise, mainly caused by the low signal‐to‐noise (S/N) earth environment. A variance fractal dimension (VFD) technique is investigated and tested with real data sets for detection of seismic refraction signals from background noise. The data tested in this study were collected during the 1992 Lithoprobe Abitibi‐Grenville Transect high‐resolution refraction and wide‐angle reflection seismic experiments. The sharpness of transition features on the VFD trajectory is used as a criterion for distinguishing specific seismic phases. The window size and window interval applied in the application of VFD technique were determined using synthetic seismic data for generation of the optimum VFD trajectory. The window size of 48 samples and the window interval of 8 sample intervals were chosen to calculate the fractal dimension values and create the trajectories for detecting phases Pg, Pn, PmP, and ground roll. The VFD technique was also tested and applied for automatic detection of the first breaks in the high‐resolution seismic reflection data collected during the 1990 Lithoprobe regional and high‐resolution seismic surveys. The sharp transition features corresponding to the first arrivals in the seismic reflection data are distinct and provide us with a robust and powerful tool for separating the seismic signals from noise.

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