scholarly journals Measuring and Modeling of P- and S-Wave Velocities on Crustal Rocks: A Key for the Interpretation of Seismic Reflection and Refraction Data

2011 ◽  
Vol 2011 ◽  
pp. 1-9 ◽  
Author(s):  
Hartmut Kern
Keyword(s):  
Seismic Reflection ◽  
Theoretical Calculations ◽  
Seismic Refraction ◽  
Central China ◽  
Seismic Velocities ◽  
S Wave ◽  
Velocity Anisotropy ◽  
Crustal Rocks ◽  
Wave Velocities

Lithologic interpretations of the earth crust from seismic wave velocities are non-unique so that inferences about composition can not be drawn. In order to evaluate how elastic properties of rock materials are controlled by lithology at in situ pressures and temperatures, compressional (Vp), shear wave velocities (Vs) and velocity anisotropy of crustal rocks were measured at conditions of greater depth. The first part deals with the interdependence of elastic wave propagation and the physical and lithological parameters. In the second part data from laboratory seismic measurements and theoretical calculations are used to interpret (1) a shallow seismic reflection line (SE Finland) and (2) a refraction profile of a deep crust (Central China). The comparison of the calculated velocities with the experimentally-derived in situ velocities of the Finnish crustal rocks give hints that microcracks have an important bearing on the in situ seismic velocities, velocity anisotropy and the reflectivity observed at relative shallow depth. The coupling of the experimentally-derived in situ velocities of P- and S-wave and corresponding Poisson's ratios of relevant exhumed high-grade metamorphic crustal rocks from Central China with respective data from seismic refraction profiling provided a key for the lithologic interpretation of a deep seismic crustal structure.

Seismic Microzonation for Denizli Metropolitan Area, Turkey

2015 ◽  
Vol 802 ◽  
pp. 40-44
Author(s):  
Ali Aydin ◽  
Erdal Akyol ◽  
Mahmud Gungor ◽  
Nuray Soyatik ◽  
Suat Tasdelen
Keyword(s):  
Urban Areas ◽  
Seismic Refraction ◽  
Seismic Microzonation ◽  
Seismic Velocities ◽  
Two Dimensional ◽  
S Wave ◽  
City Center ◽  
Wave Velocities ◽  
Municipal Authority ◽  
Use Studies

This study presents microzonation of the Denizli city center, is about 225 km2. It is mainly rely on t seismic velocities of the tested soil. For seismic microzonation area of has been selected as the study area. Seismic refraction methods have been used to generate two-dimensional profiles at 310 locations. These p and s wave velocities are used to estimate boundaries of the velocities at every 2 and 5 m intervals up to a depth of 60 m. The results are satisfactory for urban planning and it can successfully be used in urban areas. The municipal authority may be considered to use the results for land use studies.

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.

Velocity anisotropy in shale determined from crosshole seismic and vertical seismic profile data

Geophysics ◽  
1990 ◽  
Vol 55 (4) ◽  
pp. 470-479 ◽  
Author(s):  
D. F. Winterstein ◽  
B. N. P. Paulsson
Keyword(s):  
Seismic Profile ◽  
P Wave ◽  
Isotropic Model ◽  
S Wave ◽  
Vertical Seismic Profile ◽  
Near Surface ◽  
S Waves ◽  
Velocity Anisotropy ◽  
Wave Velocities ◽  
Late Tertiary

Crosshole and vertical seismic profile (VST) data made possible accurate characterization of the elastic properties, including noticeable velocity anisotropy, of a near‐surface late Tertiary shale formation. Shear‐wave splitting was obvious in both crosshole and VSP data. In crosshole data, two orthologonally polarrized shear (S) waves arrived 19 ms in the uppermost 246 ft (75 m). Vertically traveling S waves of the VSP separated about 10 ms in the uppermost 300 ft (90 m) but remained at nearly constant separation below that level. A transversely isotropic model, which incorporates a rapid increase in S-wave velocities with depth but slow increase in P-wave velocities, closely fits the data over most of the measured interval. Elastic constants of the transvesely isotropic model show spherical P- and [Formula: see text]wave velocity surfaces but an ellipsoidal [Formula: see text]wave surface with a ratio of major to minor axes of 1.15. The magnitude of this S-wave anisotropy is consistent with and lends credence to S-wave anisotropy magnitudes deduced less directly from data of many sedimentary basins.

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

Geophysics ◽  
2004 ◽  
Vol 69 (2) ◽  
pp. 440-459 ◽  
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.

Shallow P- and S-Wave Velocities and Site Resonances in the St. Louis Region, Missouri-Illinois

2007 ◽  
Vol 23 (3) ◽  
pp. 711-726 ◽  
Author(s):  
Robert A. Williams ◽  
Jack K. Odum ◽  
William J. Stephenson ◽  
Robert B. Herrmann
Keyword(s):  
Urban Areas ◽  
Seismic Refraction ◽  
Hazard Mapping ◽  
University Campus ◽  
S Wave ◽  
Ground Shaking ◽  
Saint Louis ◽  
Saint Louis University ◽  
Wave Velocities ◽  
River Floodplains

As part of the seismic hazard–mapping efforts in the St. Louis metropolitan area we determined the compressional and shear-wave velocities (Vp and Vs) to about a 40-m depth at 17 locations in this area. The Vs measurements were made using high-resolution seismic refraction and reflection methods. We find a clear difference in the Vs profiles between sites located on the river floodplains and those located in the upland urban areas of St. Louis. Vs30 (average Vs to 30-m depth) values in floodplain areas range from 200 to 290 m/s (NEHRP category D) and contrast with sites on the upland areas of St. Louis, which have Vs30 values ranging from 410 to 785 m/s (NEHRP categories C and B). The lower Vs30 values and earthquake recordings in the floodplains suggest a greater potential for stronger and more prolonged ground shaking in an earthquake. Spectral analysis of a M3.6 earthquake recorded on the St. Louis–area ANSS seismograph network indicates stronger shaking and potentially damaging S-wave resonant frequencies at NEHRP category D sites compared to ground motions at a rock site located on the Saint Louis University campus.

scholarly journals Effectiveness of in situ P-wave measurements in monuments: examples from Greece

2000 ◽  
Vol 22 ◽  
Author(s):  
B. Christaras
Keyword(s):  
Modulus Of Elasticity ◽  
Building Stone ◽  
P Wave ◽  
Mechanical Anisotropy ◽  
Laboratory Measurements ◽  
S Wave ◽  
Wave Velocities ◽  
Wave Measurements ◽  
Made In

P and S wave velocities can be used for both in situ and laboratory measurements of stones. These methods are used for studying such properties as mechanical anisotropy and modulus of elasticity. In this paper, the P-wave velocities were used for the estimation of the depth of weathered or artificially consolidated layers as well as the depth of cracks developed at the surface of the building stone. This estimation was made in relation to the lithology and texture of the materials, given that in many cases different lithological data create similar diagrams. All tests were carried out on representative monuments in Greece.

The structure of Archean–Ketilidian crust along the continental shelf of southwestern Greenland from a seismic refraction profile

1992 ◽  
Vol 29 (2) ◽  
pp. 301-313 ◽  
Author(s):  
Deping Chian ◽  
Keith Louden
Keyword(s):  
Lower Crust ◽  
Velocity Structure ◽  
Seismic Refraction ◽  
Mobile Belt ◽  
Ocean Bottom ◽  
Upper Crust ◽  
S Wave ◽  
Seismic Line ◽  
Wave Velocities ◽  
Air Gun

The velocity structure of the continental crust on the outer shelf of southwestern Greenland is determined from dense wide-angle reflection–refraction data obtained with large air-gun sources and ocean bottom seismometers along a 230 km seismic line. This line crosses the geological boundary between the Archean block and the Ketilidian mobile belt. Although the data have high noise levels, P- and S-wave arrivals from within the upper, intermediate, and lower crust, and at the Moho boundary, can be consistently identified and correlated with one-dimensional WKBJ synthetic seismograms. In the Archean, P- and S-wave velocities in the upper crust are 6.0 and 3.4 km/s, while in the intermediate crust they are 6.4 and 3.6 km/s. These velocities match for the upper crust a quartz–feldspar gneiss composition and for the intermediate crust an amphibolitized pyroxene granulite. In the Ketilidian mobile belt, P- and S-wave velocities are 5.6 and 3.3 km/s for the upper crust and 6.3 and 3.6 km/s for the intermediate crust. These velocities may represent quartz granite in the upper crust and granite and granitic gneiss in the intermediate crust. The upper crust is ~5 km thick in the Archean block and the Ketilidian mobile belt, and thickens to ~9 km in the southern part of the Archean. This velocity structure supports a Precambrian collisional mechanism between the Archean block and Ketilidian mobile belt. The lower crust has a small vertical velocity gradient from 6.6 km/s at 15 km depth to 6.9 km/s at 30 km depth (Moho) along the refraction line, with a nearly constant S-wave velocity around 3.8 km/s. These velocities likely represent a gabbroic and hornblende granulite composition for the lower crust. This typical (but somewhat thin) Precambrian crustal velocity structure in southwestern Greenland shows no evidence for a high-velocity, lower crustal, underplated layer caused by the Mesozoic opening of the Labrador Sea.

scholarly journals P- and S-wave velocities of the lowermost crustal rocks from the Kohistan arc: Implications for seismic Moho discontinuity attributed to abundant garnet

2009 ◽  
Vol 467 (1-4) ◽  
pp. 44-54 ◽  
Author(s):  
Yoshio Kono ◽  
Masahiro Ishikawa ◽  
Yumiko Harigane ◽  
Katsuyoshi Michibayashi ◽  
Makoto Arima
Keyword(s):  
Moho Discontinuity ◽  
S Wave ◽  
Crustal Rocks ◽  
Wave Velocities

P-to-S-wave velocity ratio in organic shales

Geophysics ◽  
2019 ◽  
Vol 84 (6) ◽  
pp. MR205-MR222 ◽  
Author(s):  
Sheyore John Omovie ◽  
John P. Castagna
Keyword(s):  
Wave Velocity ◽  
Pore Space ◽  
Velocity Ratio ◽  
Organic Content ◽  
Theoretical Modeling ◽  
S Wave ◽  
Lower Velocity ◽  
Wave Velocities ◽  
Ultrasonic Measurements

In situ P- and S-wave velocity measurements in a variety of organic-rich shales exhibit P-to-S-wave velocity ratios that are significantly lower than lithologically similar fully brine-saturated shales having low organic content. It has been hypothesized that this drop could be explained by the direct influence of kerogen on the rock frame and/or by the presence of free hydrocarbons in the pore space. The correlation of hydrocarbon saturation with total organic content in situ makes it difficult to separate these possible mechanisms using log data alone. Theoretical bounding equations, using pure kerogen as an end-member component without associated gas, indicate that kerogen reduces the P- and S-wave velocities but does not in general reduce their ratio enough to explain the observed low velocity ratio. The theoretical modeling is consistent with ultrasonic measurements on organic shale core samples that indicate no dependence of velocity ratios on the kerogen volume alone. Sonic log measurements of P- and S-wave velocities in seven organic-rich shale formations deviate significantly (typically more than 5%) from the Greenberg-Castagna empirical brine-saturated shale trend toward lower velocity ratios. In these formations, and on core measurements, Gassmann fluid substitution to 100% brine saturation yields velocity ratios consistent with the Greenberg-Castagna velocity trend for fully brine-saturated shales, despite the high organic content. These sonic and ultrasonic measurements, as well as theoretical modeling, suggest that the velocity ratio reduction in organic shales is best explained by the presence of free hydrocarbons.

EXPERIMENTAL EVALUATION OF ULTRASONIC VELOCITIES AND ANISOTROPY IN THE TUSCALOOSA MARINE SHALE FORMATION

2020 ◽  
pp. 1-62 ◽  
Author(s):  
Jamal Ahmadov ◽  
Mehdi Mokhtari
Keyword(s):  
Wave Velocity ◽  
Mineralogical Composition ◽  
Organic Content ◽  
P Wave ◽  
S Wave ◽  
Velocity Anisotropy ◽  
Wave Velocities ◽  
Marine Shale ◽  
P Wave Velocity ◽  
Degree Of Anisotropy

Tuscaloosa Marine Shale (TMS) formation is a clay- and organic-rich emerging shale play with a considerable amount of hydrocarbon resources. Despite the substantial potential, there have been only a few wells drilled and produced in the formation over the recent years. The analyzed TMS samples contain an average of 50 wt% total clay, 27 wt% quartz and 14 wt% calcite and the mineralogy varies considerably over the small intervals. The high amount of clay leads to pronounced anisotropy and the frequent changes in mineralogy result in the heterogeneity of the formation. We studied the compressional (VP) and shear-wave (VS) velocities to evaluate the degree of anisotropy and heterogeneity, which impact hydraulic fracture growth, borehole instabilities, and subsurface imaging. The ultrasonic measurements of P- and S-wave velocities from five TMS wells are the best fit to the linear relationship with R2 = 0.84 in the least-squares criteria. We observed that TMS S-wave velocities are relatively lower when compared to the established velocity relationships. Most of the velocity data in bedding-normal direction lie outside constant VP/VS lines of 1.6–1.8, a region typical of most organic-rich shale plays. For all of the studied TMS samples, the S-wave velocity anisotropy exhibits higher values than P-wave velocity anisotropy. In the samples in which the composition is dominated by either calcite or quartz minerals, mineralogy controls the velocities and VP/VS ratios to a great extent. Additionally, the organic content and maturity account for the velocity behavior in the samples in which the mineralogical composition fails to do so. The results provide further insights into TMS Formation evaluation and contribute to a better understanding of the heterogeneity and anisotropy of the play.

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