A Preliminar P And S-Wave Receiver Functions Study At Ktut Station (Trabzon, Turkey)

Author(s):  
H. Alkan ◽  
H. Çinar
Keyword(s):  
2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Philipp Balling ◽  
Christoph Grützner ◽  
Bruno Tomljenović ◽  
Wim Spakman ◽  
Kamil Ustaszewski

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.


2019 ◽  
Vol 62 (11) ◽  
pp. 1819-1831
Author(s):  
Xu Wang ◽  
Ling Chen ◽  
Yuan Ling ◽  
Yifan Gao ◽  
Jianyong Zhang ◽  
...  

2020 ◽  
Vol 223 (3) ◽  
pp. 2009-2026
Author(s):  
Frederik Link ◽  
Georg Rümpker ◽  
Ayoub Kaviani

SUMMARY We present a technique to derive robust estimates for the crustal thickness and elastic properties, including anisotropy, from shear wave splitting of converted phases in receiver functions. We combine stacking procedures with a correction scheme for the splitting effect of the crustal converted Ps-phase and its first reverberation, the PpPs-phase, where we also allow for a predefined dipping Moho. The incorporation of two phases stabilizes the analysis procedure and allows to simultaneously solve for the crustal thickness, the ratio of average P- to S-wave velocities, the percentage of anisotropy and the fast-axis direction. The stacking is based on arrival times and polarizations computed using a ray-based algorithm. Synthetic tests show the robustness of the technique and its applicability to tectonic settings where dip of the Moho is significant. These tests also demonstrate that the effects of a dipping layer boundary may overprint a possible anisotropic signature. To constrain the uncertainty of our results we perform statistical tests based on a bootstrapping approach. We distinguish between different model classes by comparing the coherency of the stacked amplitudes after moveout correction. We apply the new technique to real-data examples from different tectonic regimes and show that coherency of the stacked receiver functions can be improved, when anisotropy and a dipping Moho are included in the analysis. The examples underline the advantages of statistical analyses when dealing with stacking procedures and potentially ambiguous solutions.


2020 ◽  
Author(s):  
Wei Li ◽  
Yun Chen ◽  
Ping Tan ◽  
Xiaohui Yuan

<p>The Pamir plateau, located north of the western syntaxis of the India­–Eurasia collision system, is regarded as one of the most possible places of the ongoing continental deep subduction. Based on a N-S trending linear seismic array across the Pamir plateau, we use the methods of harmonic analysis of receiver functions and the cubic spline interpolation of surface wave dispersions to coordinate their resolutions, and perform a joint inversion of these datasets to construct a 2-D S-wave velocity model of the crust and uppermost mantle. A spatial configuration among the intermediate-depth seismicity, Moho topography, and low-velocity zone(LVZ)s within the crust and upper mantle is revealed. The intermediate-depth seismic zone is enclosed in a mantle LVZ which extends upward to the crustal root and connects with a lower crustal LVZ in the northern Pamir. Just above it, another crustal LVZ is collocated with a Moho uplift. These results not only further confirm the deep subduction of the Asian lower continental crust beneath the Pamir plateau, but also indicate the importance of the metamorphic dehydration of the subducting continental crustal material in the genesis of the intermediate-depth seismicity and crustal deformation.</p>


2020 ◽  
Author(s):  
Kazunori Yoshizawa ◽  
Toru Taira

<p>Upper mantle structures under cratons have recently been investigated by many researchers using receiver functions and surface waves to clarify the nature of the Lithosphere-Asthenosphere Boundary (LAB) and Mid-Lithosphere Discontinuity (MLD). Majority of seismological studies of joint inversions using receiver functions and surface waves have employed dispersion curves of fundamental-mode only, but higher-mode information is essential for resolving the whole depth range of thick continental lithosphere (over 200 km) and its underlying asthenosphere.</p><p>In this study, we reconstructed radially anisotropic S wave models including multiple discontinuities in the upper mantle under seismic stations in Australia, using multi-mode surface waves and receiver functions in the framework of the Bayesian inference. We employed a fully nonlinear method of joint inversions incorporating P-to-S receiver functions and multi-mode Rayleigh and Love waves, based on the trans-dimensional hierarchical Bayesian formulation. The method allows us to estimate a probabilistic Earth model taking account of the complexity and uncertainty of Earth structure, by treating the model parameters and data errors as unknowns. The Parallel Tempering algorithm is incorporated for the effective parameter search based on the reversible-jump Markov Chain Monte Carlo method.</p><p>Multi-mode phase speed maps of surface waves developed by Yoshizawa (2014) are used to extract localized multi-mode dispersion curves. The use of higher-mode surface waves enables us to enhance the sensitivity to the depth below the continental asthenosphere, while the receiver functions allows us to better constrain the depths of discontinuities and velocity jumps. Synthetic experiments indicate the importance of higher-mode information for the better recovery of radial anisotropy in the whole depth range of the upper mantle.</p><p>The method has been applied to Global Seismographic Network stations in Australia. While the S-wave models in eastern Australia show shallow LAB above 100 km depth, those in central and western Australia exhibit both MLD and LAB. Also, seismic velocity jumps equivalent to the Lehmann Discontinuity (LD) are found in all seismic stations in Australia. The LDs under the Australian continents are found at the depth of around 200 - 300 km, depending on locations. Radial anisotropy in the depth range between LAB and LD tends to show faster SH anomalies, which may indicate the effects of horizontal shear underneath the fast-moving Australian plate.</p>


2009 ◽  
Vol 177 (3-4) ◽  
pp. 206-216 ◽  
Author(s):  
D.A. Angus ◽  
J.-M. Kendall ◽  
D.C. Wilson ◽  
D.J. White ◽  
S. Sol ◽  
...  

2015 ◽  
Vol 65 (2) ◽  
pp. 239-255 ◽  
Author(s):  
Abdullah M. Al-Amri

Abstract New velocity models of lithospheric thickness and velocity structure have been developed for the Arabian Shield by three tasks: 1) Computing P-Wave Receiver Functions (PRFs) and S-Wave Receiver Functions (SRFs) for all the broadband stations within the Saudi seismic networks. The number of receiver function waveforms depends on the recording time window and quality of the broadband station. 2) Computing ambient noise correlation Green’s functions for all available station pairs within the Saudi seismic networks to image the shear velocity in the crust and uppermost mantle beneath the Arabian Peninsula. Together they provided hundreds of additional, unique paths exclusively sampling the region of interest. Both phase and group velocities for all the resulting empirical Green’s functions have been measured and to be used in the joint inversion. 3) Jointly inverted the PRFs and SRFs obtained in task 1 with dispersion velocities measured on the Green’s functions obtained in task 2 and with fundamental-mode, Rayleigh-wave, group and phase velocities borrowed from the tomographic studies to precisely determine 1D crustal velocity structure and upper mantle. The analysis of the PRFs revealed values of 25-45 km for crustal thickness, with the thin crust next to the Red Sea and Gulf of Aqaba and the thicker crust under the platform, and Vp/Vs ratios in the 1.70-1.80 range, suggesting a range of compositions (felsic to mafic) for the shield’s crust. The migrated SRFs suggest lithospheric thicknesses in the 80-100 km range for portions of the shield close to the Red Sea and Gulf of Aqaba and near the Arabian Gulf. Generally, the novelty of the velocity models developed under this paper has consisted in the addition of SRF data to extend the velocity models down to lithospheric and sub-lithospheric depths.


2014 ◽  
Vol 51 (4) ◽  
pp. 407-417 ◽  
Author(s):  
H.S. Kim ◽  
J.F. Cassidy ◽  
S.E. Dosso ◽  
H. Kao

This paper presents results of a passive-source seismic mapping study in the Nechako–Chilcotin plateau of central British Columbia, with the ultimate goal of contributing to assessments of hydrocarbon and mineral potential of the region. For the present study, an array of nine seismic stations was deployed in 2006–2007 to sample a wide area of the Nechako–Chilcotin plateau. The specific goal was to map the thickness of the sediments and volcanic cover, and the overall crustal thickness and structural geometry beneath the study area. This study utilizes recordings of about 40 distant earthquakes from 2006 to 2008 to calculate receiver functions, and constructs S-wave velocity models for each station using the Neighbourhood Algorithm inversion. The surface sediments are found to range in thickness from about 0.8 to 2.7 km, and the underlying volcanic layer from 1.8 to 4.7 km. Both sediments and volcanic cover are thickest in the central portion of the study area. The crustal thickness ranges from 22 to 36 km, with an average crustal thickness of about 30–34 km. A consistent feature observed in this study is a low-velocity zone at the base of the crust. This study complements other recent studies in this area, including active-source seismic studies and magnetotelluric measurements, by providing site-specific images of the crustal structure down to the Moho and detailed constraints on the S-wave velocity structure.


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