Using multicomponent VSP data to constrain s‐wave splitting observed in near surface seismic reflection data from the Savannah River Site

A multioffset, three‐component vertical seismic profiling (VSP) experiment was carried out in the Sudbury Basin, Ontario, as a part of the LITHOPROBE Sudbury Transect. The main objectives were determination of the shallow velocity structure in the middle of the Sudbury Basin, development of an effective VSP data processing flow, correlation of the VSP survey results with the surface seismic reflection data, and demonstration of the usefulness of the VSP method in a crystalline rock environment. The VSP data processing steps included rotation of the horizontal component data, traveltime inversion for velocity analysis, Radon transform for wavefield separation, and preliminary analysis of shear‐wave data. After wavefield separation, the flattened upgoing wavefields for both P‐waves and S‐waves display consistent reflection events from three depth levels. The VSP-CDP transformed section and corridor stacked section correlate well with the high‐resolution surface reflection data. In addition to obtaining realistic velocity models for both P‐ and S‐waves through least‐square inversion and synthetic seismic modeling for the Chelmsford area, the VSP experiment provided an independent estimation for the reflector dip using three component hodogram analysis, which indicates that the dip of the contact between the Chelmsford and Onwatin formations, at an approximate depth of 380 m in the Chelmsford borehole, is approximately 10.5° southeast. This study demonstrates that multioffset, three‐component VSP experiments can provide important constraints and auxiliary information for shallow crustal seismic studies in crystalline terrain. Thus, the VSP technique bridges the gap between the surface seismic‐reflection technique and well‐log surveys.

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Automating the acquisition of 3D near‐surface seismic reflection data

10.1190/1.3255092 ◽

2009 ◽

Author(s):

Steven D. Sloan ◽

Don W. Steeples ◽

Georgios P. Tsoflias ◽

Mihan H. McKenna

Keyword(s):

Seismic Reflection ◽

Seismic Reflection Data ◽

Near Surface ◽

Reflection Data

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Integrating S‐wave seismic‐reflection data and cone penetration test data using a multiangle multiscale approach

Geophysics ◽

10.1190/1.1707064 ◽

2004 ◽

Vol 69 (2) ◽

pp. 440-459 ◽

Cited By ~ 32

Author(s):

Ranajit Ghose ◽

Jeroen Goudswaard

Keyword(s):

Wave Velocity ◽

Seismic Reflection ◽

Multiscale Analysis ◽

S Wave ◽

Cone Penetration ◽

Seismic Reflection Data ◽

Cone Resistance ◽

Reflection Seismic ◽

Reflection Data

A cone penetration test (CPT) is the most common geotechnical testing method used to estimate in situ the strength properties of soil. Although CPT provides valuable information, this information is restricted to the location of the measurement. We propose a new concept to integrate shallow S‐wave reflection seismic data with CPT data in order to obtain laterally continuous subsoil information. In this vein, a valid quantitative means to relate seismic reflections to CPT data is a primary requirement. The approach proposed here is based on the characterization of the scaling behavior of the local fine‐scale S‐wave velocity information extracted from the seismic reflection data and the same behavior of the CPT cone resistance. The local velocity contrast information is extracted by linearized Zoeppritz inversion of the amplitude‐preserved prestack reflection data. We have formulated a multiscale analysis approach employing the continuous wavelet transform in order to quantitatively characterize the nature of change at an interface of the local S‐wave velocity contrast and the CPT cone resistance and to illuminate any relation between these two. The multiscale analysis estimates the singularity parameter α, which indicates the nature of the interfacial change. The application of our method to the field data has uncovered a striking relation between the nature of variation of the local S‐wave velocity contrast and that of CPT cone resistance; otherwise, such a relation was not visible. Detailed analyses of two extensive field datasets have shown that the lateral fine‐scale variation of soil strength, as seen by CPT cone resistance, has a close resemblance with the variation of the local S‐wave velocity function as seen by angle‐dependent reflection measurements. This leads to a unique possibility to integrate two very different in‐situ measurements—reflection seismic and CPT—providing laterally continuous detailed information of the soil layer boundaries.

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Tomographic determination of velocity and depth in laterally varying media

Geophysics ◽

10.1190/1.1441970 ◽

1985 ◽

Vol 50 (6) ◽

pp. 903-923 ◽

Cited By ~ 346

Author(s):

T. N. Bishop ◽

K. P. Bube ◽

R. T. Cutler ◽

R. T. Langan ◽

P. L. Love ◽

...

Keyword(s):

Seismic Reflection ◽

Seismic Velocity ◽

Real Data ◽

Seismic Reflection Data ◽

Near Surface ◽

Reflection Data ◽

Tomographic Method ◽

Recorded Data ◽

The Difference

Estimation of reflector depth and seismic velocity from seismic reflection data can be formulated as a general inverse problem. The method used to solve this problem is similar to tomographic techniques in medical diagnosis and we refer to it as seismic reflection tomography. Seismic tomography is formulated as an iterative Gauss‐Newton algorithm that produces a velocity‐depth model which minimizes the difference between traveltimes generated by tracing rays through the model and traveltimes measured from the data. The input to the process consists of traveltimes measured from selected events on unstacked seismic data and a first‐guess velocity‐depth model. Usually this first‐guess model has velocities which are laterally constant and is usually based on nearby well information and/or an analysis of the stacked section. The final model generated by the tomographic method yields traveltimes from ray tracing which differ from the measured values in recorded data by approximately 5 ms root‐mean‐square. The indeterminancy of the inversion and the associated nonuniqueness of the output model are both analyzed theoretically and tested numerically. It is found that certain aspects of the velocity field are poorly determined or undetermined. This technique is applied to an example using real data where the presence of permafrost causes a near‐surface lateral change in velocity. The permafrost is successfully imaged in the model output from tomography. In addition, depth estimates at the intersection of two lines differ by a significantly smaller amount than the corresponding estimates derived from conventional processing.

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An example of extreme near-surface variability in shallow seismic reflection data

Interpretation ◽

10.1190/int-2015-0215.1 ◽

2016 ◽

Vol 4 (3) ◽

pp. SH1-SH9

Author(s):

Steven D. Sloan ◽

J. Tyler Schwenk ◽

Robert H. Stevens

Keyword(s):

Seismic Reflection ◽

Field Data ◽

Low Velocity ◽

Seismic Reflection Data ◽

Near Surface ◽

Shallow Subsurface ◽

Reflection Data ◽

Shallow Seismic ◽

Low Velocity Layer ◽

Velocity Layer

Variability of material properties in the shallow subsurface presents challenges for near-surface geophysical methods and exploration-scale applications. As the depth of investigation decreases, denser sampling is required, especially of the near offsets, to accurately characterize the shallow subsurface. We have developed a field data example using high-resolution shallow seismic reflection data to demonstrate how quickly near-surface properties can change over short distances and the effects on field data and processed sections. The addition of a relatively thin, 20 cm thick, low-velocity layer can lead to masked reflections and an inability to map shallow reflectors. Short receiver intervals, on the order of 10 cm, were necessary to identify the cause of the diminished data quality and would have gone unknown using larger, more conventional station spacing. Combined analysis of first arrivals, surface waves, and reflections aided in determining the effects and extent of a low-velocity layer that inhibited the identification and constructive stacking of the reflection from a shallow water table using normal-moveout-based processing methods. Our results also highlight the benefits of using unprocessed gathers to pragmatically guide processing and interpretation of seismic data.

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Using Seismic Attributes in seismotectonic research: an application to the Norcia's Mw = 6.5 earthquake (30th October 2016) in Central Italy

10.5194/se-2019-108 ◽

2019 ◽

Author(s):

Maurizio Ercoli ◽

Emanuele Forte ◽

Massimiliano Porreca ◽

Ramon Carbonell ◽

Cristina Pauselli ◽

...

Keyword(s):

Seismic Reflection ◽

Central Italy ◽

Seismic Attributes ◽

Seismic Attribute ◽

Data Set ◽

Epicentral Zone ◽

Seismic Reflection Data ◽

Near Surface ◽

Reflection Data ◽

Attribute Analysis

Abstract. In seismotectonic studies, seismic reflection data are a powerful tool to unravel the complex deep architecture of active faults. Such tectonic structures are usually mapped at surface through traditional geological surveying whilst seismic reflection data may help to trace their continuation from the near-surface down to hypocentral depth. In this study, we propose the application of the seismic attributes technique, commonly used in seismic reflection exploration by oil industry, to seismotectonic research for the first time. The study area is a geologically complex region of Central Italy, recently struck by a long-lasting seismic sequence including a Mw 6.5 main-shock. A seismic reflection data-set consisting of three vintage seismic profiles, currently the only available across the epicentral zone, constitutes a singular opportunity to attempt a seismic attribute analysis. This analysis resulted in peculiar seismic signatures which generally correlate with the exposed surface geologic features, and also confirming the presence of other debated structures. These results are critical, because provide information also on the relatively deep structural setting, mapping a prominent, high amplitude regional reflector that marks the top basement, interpreted as important rheological boundary. Complex patterns of high-angle discontinuities crossing the reflectors have been also identified. These dipping fabrics are interpreted as the expression of fault zones, belonging to the active normal fault systems responsible for the seismicity of the region. This work demonstrates that seismic attribute analysis, even if used on low-quality vintage 2D data, may contribute to improve the subsurface geological interpretation of areas characterized by high seismic potential.

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Characterization of a Concealed Fault Zone Using P and S-wave Seismic Reflection Data

Near Surface 2009 - 15th EAGE European Meeting of Environmental and Engineering Geophysics ◽

10.3997/2214-4609.20146999 ◽

2009 ◽

Cited By ~ 3

Author(s):

J. Carvalho ◽

R. Ghose ◽

C. Pinto ◽

J. Borges

Keyword(s):

Fault Zone ◽

Seismic Reflection ◽

S Wave ◽

Seismic Reflection Data ◽

Reflection Data

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Time-lapse imaging using 3D ultra-high-frequency marine seismic reflection data

Geophysics ◽

10.1190/geo2019-0258.1 ◽

2020 ◽

Vol 85 (2) ◽

pp. P13-P25

Author(s):

Michael J. Faggetter ◽

Mark E. Vardy ◽

Justin K. Dix ◽

Jonathan M. Bull ◽

Timothy J. Henstock

Keyword(s):

High Frequency ◽

Seismic Reflection ◽

High Tide ◽

Time Lapse ◽

Data Set ◽

Seismic Reflection Data ◽

Near Surface ◽

Ultra High Frequency ◽

Reflection Data ◽

Marine Seismic

Time-lapse (4D) seismic imaging is now widely used as a tool to map and interpret changes in deep reservoirs as well as investigate dynamic, shallow hydrological processes in the near surface. However, there are very few examples of time-lapse analysis using ultra-high-frequency (UHF; kHz range) marine seismic reflection data. Exacting requirements for navigation can be prohibitive for acquiring coherent, true-3D volumes. Variable environmental noise can also lead to poor amplitude repeatability and make it difficult to identify differences that are related to real physical changes. Overcoming these challenges opens up a range of potential applications for monitoring the subsurface at decimetric resolution, including geohazards, geologic structures, as well as the bed-level and subsurface response to anthropogenic activities. Navigation postprocessing was incorporated to improve the acquisition and processing workflow for the 3D Chirp subbottom profiler and provide stable, centimeter-level absolute positioning, resulting in well-matched 3D data and mitigating 4D noise for data stacked into [Formula: see text] common-midpoint bins. Within an example 4D data set acquired on the south coast of the UK, interpretable differences are recorded within a shallow gas blanket. Reflections from the top and bottom of a gas pocket are imaged at low tide, whereas at high tide only the upper reflection is imaged. This case study demonstrates the viability of time-lapse UHF 3D seismic reflection for quantitative mapping of decimeter-scale changes within the shallow marine subsurface.

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