Toward Simultaneous Determination of Bulk Crustal Properties Using Virtual Deep Seismic Sounding

2020 ◽  
Vol 110 (3) ◽  
pp. 1387-1392 ◽  
Author(s):  
Qing Chen ◽  
Wang-Ping Chen
Keyword(s):  
Wave Train ◽  
Silica Content ◽  
P Wave ◽  
Deep Seismic Sounding ◽  
Wide Angle ◽  
Virtual Source ◽  
S Wave ◽  
Large Signal ◽  
Seismic Sounding ◽  
Central Tibet

ABSTRACT We augment the method of virtual deep seismic sounding (VDSS) by adding the phases Sp, the SV-P conversion across the Moho, to determine the average speed of the S wave (VS) in the crust. VDSS uses the strong SV-P conversion below the free surface from teleseismic earthquakes as a virtual source for wide-angle reflections of the P wave. The large signal generated by the virtual source is the strongest aspect of VDSS in which no stacking is necessary to build up the signal. Previous work used the large moveout of the wide-angle reflection, phase SsPmp, relative to the direct S-wave arrival, phase Ss, to minimize the trade-off between bulk P-wave speed (VP) and thickness of the crust (H). It is then straightforward to use the timing of the phase Sp to constrain VS. As examples, we show that this method works for data from both temporary and permanent seismic deployments in contrasting tectonic settings. Specifically, VS under station FORT in western Australia and H1620 in central Tibet are 3.77±0.08 and 3.42±0.11  km/s, respectively. This development complements the undertaking of using information from only the S-wave train to extract all three seismic parameters of the bulk crust, VP, VS, and H. These parameters are important for constraining overall silica content of the crust.

Crustal P wave velocity structure beneath the SE margin of the Tibetan Plateau from Deep Seismic Sounding results

2019 ◽  
Vol 755 ◽  
pp. 109-126
Author(s):  
Jiyan Lin ◽  
Walter D. Mooney ◽  
Fuyun Wang ◽  
Yonghong Duan ◽  
Xiaofeng Tian ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Wave Velocity ◽  
Velocity Structure ◽  
P Wave ◽  
Deep Seismic Sounding ◽  
The Tibetan Plateau ◽  
P Wave Velocity ◽  
Seismic Sounding ◽  
P Wave Velocity Structure

Elastic inversion of near- and postcritical reflections using phase variation with angle

Geophysics ◽  
2012 ◽  
Vol 77 (4) ◽  
pp. R149-R159 ◽  
Author(s):  
Xinfa Zhu ◽  
George A. McMechan
Keyword(s):  
Wave Velocity ◽  
Spherical Wave ◽  
Phase Variation ◽  
P Wave ◽  
Wide Angle ◽  
Reverse Time ◽  
Reverse Time Migration ◽  
S Wave ◽  
Time Migration ◽  
Elastic Inversion

Near- and postcritical (wide-angle) reflections provide the potential for velocity and density inversion because of their large amplitudes and phase-shifted waveforms. We tested using phase variation with angle (PVA) data in addition to, or instead of, amplitude variation with angle (AVA) data for elastic inversion. Accurate PVA test data were generated using the reflectivity method. Two other forward modeling methods were also investigated, including plane-wave and spherical-wave reflection coefficients. For a two half-space model, linearized least squares was used to invert PVA and AVA data for the P-wave velocity, S-wave velocity, and the density of the lower space and the S-wave velocity of the upper space. Inversion tests showed the feasibility and robustness of PVA inversion. A reverse-time migration test demonstrated better preservation of PVA information than AVA information during wavefield propagation through a layered overburden. Phases of deeper reflections were less affected than amplitudes by the transmission losses, which makes the results of PVA inversion more accurate than AVA inversion in multilayered media. PVA brings useful information to the elastic inversion of wide-angle reflections.

INDEPTH Wide-Angle Reflection Observation of P-Wave-to-S-Wave Conversion from Crustal Bright Spots in Tibet

Science ◽  
1996 ◽  
Vol 274 (5293) ◽  
pp. 1690-1691 ◽  
Author(s):  
Y. Makovsky ◽  
S. L. Klemperer ◽  
L. Ratschbacher ◽  
L. D. Brown ◽  
M. Li ◽  
...  
Keyword(s):  
P Wave ◽  
Wide Angle ◽  
S Wave ◽  
Bright Spots ◽  
Wave Conversion

Shear‐wave logging with dipole sources

Geophysics ◽  
1988 ◽  
Vol 53 (5) ◽  
pp. 659-667 ◽  
Author(s):  
S. T. Chen
Keyword(s):  
Shear Wave ◽  
Wave Velocity ◽  
Wave Train ◽  
P Wave ◽  
Dipole Source ◽  
Stoneley Wave ◽  
S Wave ◽  
S Waves ◽  
On Line ◽  
First Arrival

Laboratory measurements have verified a novel technique for direct shear‐wave logging in hard and soft formations with a dipole source, as recently suggested in theoretical studies. Conventional monopole logging tools are not capable of measuring shear waves directly. In particular, no S waves are recorded in a soft formation with a conventional monopole sonic tool because there are no critically refracted S rays when the S-wave velocity of the rock is less than the acoustic velocity of the borehole fluid. The present studies were conducted in the laboratory with scale models representative of sonic logging conditions in the field. We have used a concrete model to represent hard formations and a plastic model to simulate a soft formation. The dipole source, operating at frequencies lower than those conventionally used in logging, substantially suppressed the P wave and excited a wave train whose first arrival traveled at the S-wave velocity. As a result, one can use a dipole source to log S-wave velocity directly on‐line by picking the first arrival of the full wave train, in a process similar to that used in conventional P-wave logging. Laboratory experiments with a conventional monopole source in a soft formation did not produce S waves. However, the S-wave velocity was accurately estimated by using Biot’s theory, which required measuring the Stoneley‐wave velocity and knowing other borehole parameters.

scholarly journals Fault-zone waves observed at the southern Joshua Tree earthquake rupture zone

1994 ◽  
Vol 84 (3) ◽  
pp. 761-767
Author(s):  
S. E. Hough ◽  
Y. Ben-Zion ◽  
P. Leary
Keyword(s):  
Fault Zone ◽  
Wave Train ◽  
Spectral Characteristics ◽  
P Wave ◽  
S Wave ◽  
Low Velocity ◽  
Zone Structure ◽  
High Attenuation ◽  
Vertical Fault ◽  
Synthetic Waveform

Abstract Waveform and spectral characteristics of several aftershocks of the M 6.1 22 April 1992 Joshua Tree earthquake recorded at stations just north of the Indio Hills in the Coachella Valley can be interpreted in terms of waves propagating within narrow, low-velocity, high-attenuation, vertical zones. Evidence for our interpretation consists of: (1) emergent P arrivals prior to and opposite in polarity to the impulsive direct phase; these arrivals can be modeled as headwaves indicative of a transfault velocity contrast; (2) spectral peaks in the S wave train that can be interpreted as internally reflected, low-velocity fault-zone wave energy; and (3) spatial selectivity of event-station pairs at which these data are observed, suggesting a long, narrow geologic structure. The observed waveforms are modeled using the analytical solution of Ben-Zion and Aki (1990) for a plane-parallel layered fault-zone structure. Synthetic waveform fits to the observed data indicate the presence of NS-trending vertical fault-zone layers characterized by a thickness of 50 to 100 m, a velocity decrease of 10 to 15% relative to the surrounding rock, and a P-wave quality factor in the range 25 to 50.

Anatomy of a crustal-scale accretionary complex: Insights from deep seismic sounding of the onshore western Makran subduction zone, Iran

Geology ◽  
2020 ◽  
Vol 49 (1) ◽  
pp. 3-7 ◽  
Author(s):  
Christian Haberland ◽  
Mohammad Mokhtari ◽  
Hassan Ali Babaei ◽  
Trond Ryberg ◽  
Mehdi Masoodi ◽  
...  
Keyword(s):  
Subduction Zone ◽  
P Wave ◽  
Deep Seismic Sounding ◽  
Accretionary Wedge ◽  
Makran Subduction Zone ◽  
Line Drawings ◽  
Seismic Sounding ◽  
Surface Geology ◽  
Shallow Structure ◽  
Shed Light

Abstract The Makran subduction zone has produced M 8+ earthquakes and subsequent tsunamis in historic times, hence indicating high risk for the coastal regions of southern Iran, Pakistan, and neighboring countries. Besides this, the Makran subduction zone is an end-member subduction zone featuring extreme properties, with one of the largest sediment inputs and the widest accretionary wedge on Earth. While surface geology and shallow structure of the offshore wedge have been relatively well studied, primary information on the deeper structure of the onshore part is largely absent. We present three crustal-scale, trench-perpendicular, deep seismic sounding profiles crossing the subaerial part of the accretionary wedge of the western Makran subduction zone in Iran. P-wave travel-time tomography based on a Monte Carlo Markov chain algorithm as well as the migration of automatic line drawings of wide-angle reflections reveal the crustal structure of the wedge and geometry of the subducting oceanic plate at high resolution. The images shed light on the accretionary processes, in particular the generation of continental crust by basal accretion, and provide vital basic information for hazard assessment and tsunami modeling.

scholarly journals In-Reservoir Waveform Retrieval for Monitoring at Groningen—Seismic Interferometry with Active and Passive Deep Borehole Data

2021 ◽  
Vol 13 (15) ◽  
pp. 2928
Author(s):  
Muhammad F. Akbar ◽  
Ivan Vasconcelos ◽  
Hanneke Paulssen ◽  
Wen Zhou
Keyword(s):  
Synthetic Data ◽  
P Wave ◽  
Elastic Model ◽  
Detailed Knowledge ◽  
Virtual Source ◽  
Test Bed ◽  
S Wave ◽  
Borehole Data ◽  
Gas Field ◽  
Reservoir Monitoring

The Groningen gas field in the Netherlands is an ideal test bed for in-situ reservoir monitoring techniques because of the availability of both active and passive in-reservoir seismic data. In this study, we use deconvolution interferometry to estimate the reflection and transmission response using active and passive borehole data within the reservoir at ∼3-km depth and separate up- and downgoing P- and S-wave fields by f-k filtering. We validate the results using synthetic data of a 1D elastic model built from sonic logs recorded in the well. The estimated full-waveform reflection response for a virtual source at the top geophone is consistent with the synthetic response. For the virtual source at the bottom geophone, the reflection response appears to be phase delayed, though its arrivals are consistent with the local subsurface geology. Similarly, the first-order estimated local transmission response successfully approximates that of the P-wave velocity in the reservoir. The study shows that reliable subsurface information can be obtained from borehole interferometry without detailed knowledge of the medium parameters. In addition, the method could be used for passive reservoir monitoring to detect velocity, attenuation, and/or interface time-lapse variations.

The full acoustic wave train in a laboratory model of a borehole

Geophysics ◽  
1982 ◽  
Vol 47 (11) ◽  
pp. 1512-1520 ◽  
Author(s):  
S. T. Chen
Keyword(s):  
Acoustic Wave ◽  
Wave Velocity ◽  
Theoretical Calculations ◽  
Wave Train ◽  
High Amplitude ◽  
P Wave ◽  
Laboratory Model ◽  
Stoneley Wave ◽  
S Wave ◽  
Full Wave

We studied the characteristics of acoustic wave propagation in a fluid-filled borehole using as a laboratory model a concrete cylinder 2 ft high and 2 ft in diameter with a 1/4-inch diameter borehole along its axis. The model represents sonic logging in the field reduced by a factor of 40. We recorded the full wave train consisting of a refracted compressional P wave, a refracted shear S wave, and guided waves including a number of normal modes and a Stoneley wave. Exploiting the dispersive properties of a modal wave and the source-receiver frequency characteristics, we were able to isolate the S–wave, which contains much valuable information about the formation rock, but which has not been widely used since it is difficult to extract from the full wave train. The observed Stoneley wave had a very high amplitude at low frequency and showed little dispersion. Stoneley-wave velocity is closely related to S–wave velocity and formation density, and can be measured very accurately because the Stoneley wave generally has high amplitude and low attenuation. It can therefore be used indirectly to obtain the S–wave velocity, even when the S–wave cannot be measured directly. In general, the observed characteristics of each component wave agreed with our theoretical calculations but their relative amplitudes did not. We believe these discrepancies were caused, in part, by the fact that rock attenuation and the latitudinal angular dependence of the source radiation were not taken into account in the theoretical calculations.

scholarly journals Post-collisional mantle delamination in the Dinarides implied from staircases of Oligo-Miocene uplifted marine terraces

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Philipp Balling ◽  
Christoph Grützner ◽  
Bruno Tomljenović ◽  
Wim Spakman ◽  
Kamil Ustaszewski
Keyword(s):  
Balkan Peninsula ◽  
Receiver Functions ◽  
P Wave ◽  
S Wave ◽  
Slab Geometry ◽  
Surface Uplift ◽  
River Incision ◽  
Marine Terraces ◽  
Convergence System ◽  
Internal Dinarides

AbstractThe Dinarides fold-thrust belt on the Balkan Peninsula resulted from convergence between the Adriatic and Eurasian plates since Mid-Jurassic times. Under the Dinarides, S-wave receiver functions, P-wave tomographic models, and shear-wave splitting data show anomalously thin lithosphere overlying a short down-flexed slab geometry. This geometry suggests a delamination of Adriatic lithosphere. Here, we link the evolution of this continental convergence system to hitherto unreported sets of extensively uplifted Oligocene–Miocene (28–17 Ma) marine terraces preserved at elevations of up to 600 m along the Dinaric coastal range. River incision on either side of the Mediterranean-Black Sea drainage divide is comparable to the amounts of terrace uplift. The preservation of the uplifted terraces implies that the most External Dinarides did not experience substantial deformation other than surface uplift in the Neogene. These observations and the contemporaneous emplacement of igneous rocks (33–22 Ma) in the internal Dinarides suggest that the Oligo-Miocene orogen-wide uplift was driven by post-break-off delamination of the Adriatic lithospheric mantle, this was followed by isostatic readjustment of the remaining crust. Our study details how lithospheric delamination exerts an important control on crustal deformation and that its crustal signature and geomorphic imprint can be preserved for millions of years.

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