Estimating lateral and vertical resolution in receiver function data for shallow crust exploration

SUMMARY In order to test the horizontal and vertical resolution of teleseismic receiver functions, we perform a complete receiver function analysis and inversion using data from the La Barge array. The La Barge Passive Seismic Experiment was a seismic deployment in western Wyoming, recording continuously between November 2008 and June 2009, with 55 instruments deployed 250 m apart—up to two orders of magnitude closer than in typical receiver function studies. We analyse each station separately. We calculate receiver functions and invert them using a Bayesian algorithm. The inversion results are in agreement with measurements from nearby wells, and from other studies using the same data set. The resulting posterior probability distributions (PPDs), obtained for each station, are compared to each other by computing the Bhattacharyya coefficients, which quantify the overlap between two PPDs. Our results indicate that (a) the lateral resolution of 8 Hz receiver functions is approximately equal to the width of their first Fresnel zone, (b) minimum investigable depth is about 400 m at 8 Hz, (c) lateral resolution depends on the local geology as expected and (d) velocity inversion in the shallow-crust can be resolved in the first few kilometres, even in case of dipping interfaces.

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Mapping crustal structure of the Nechako–Chilcotin plateau using teleseismic receiver function analysis,

Canadian Journal of Earth Sciences ◽

10.1139/cjes-2013-0147 ◽

2014 ◽

Vol 51 (4) ◽

pp. 407-417 ◽

Cited By ~ 2

Author(s):

H.S. Kim ◽

J.F. Cassidy ◽

S.E. Dosso ◽

H. Kao

Keyword(s):

Wave Velocity ◽

Crustal Structure ◽

Velocity Structure ◽

Receiver Function ◽

Function Analysis ◽

Crustal Thickness ◽

Receiver Functions ◽

S Wave ◽

Low Velocity ◽

Velocity Models

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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Imaging the Moho and Main Himalayan Thrust beneath the Kumaon Himalaya: constraints from receiver function analysis

Geophysical Journal International ◽

10.1093/gji/ggaa478 ◽

2020 ◽

Vol 224 (2) ◽

pp. 858-870

Author(s):

Devajit Hazarika ◽

Somak Hajra ◽

Abhishek Kundu ◽

Meena Bankhwal ◽

Naresh Kumar ◽

...

Keyword(s):

Poisson’S Ratio ◽

Receiver Function ◽

Function Analysis ◽

Crustal Thickness ◽

Receiver Functions ◽

P Wave ◽

Poisson's Ratio ◽

Kumaon Himalaya ◽

Receiver Function Analysis ◽

Lower Crustal

SUMMARY We analyse P-wave receiver functions across the Kumaon Himalaya and adjoining area to constrain crustal thickness, intracrustal structures and seismic velocity characteristics to address the role of the underlying structure on seismogenesis and geodynamic evolution of the region. The three-component waveforms of teleseismic earthquakes recorded by a seismological network consisting of 18 broad-band seismological stations have been used for receiver function analysis. The common conversion point (CCP) depth migrated receiver function image and shear wave velocity models obtained through inversion show a variation of crustal thickness from ∼38 km in the Indo-Gangetic Plain to ∼42 km near the Vaikrita Thrust. A ramp (∼20°) structure on the Main Himalayan Thrust (MHT) is revealed beneath the Chiplakot Crystalline Belt (CCB) that facilitates the exhumation of the CCB. The geometry of the MHT observed from the receiver function image is consistent with the geometry revealed by a geological balanced cross-section. A cluster of seismicity at shallow to mid-crustal depths is detected near the MHT ramp. The spatial and depth distribution of seismicity pattern beneath the CCB and presence of steep dipping imbricate faults inferred from focal mechanism solutions suggest a Lesser Himalayan Duplex structure in the CCB above the MHT ramp. The study reveals a low-velocity zone (LVZ) with a high Poisson's ratio (σ ∼0.28–0.30) at lower crustal depth beneath the CCB. The high value of Poisson's ratio in the lower crust suggests the presence of fluid/partial melt. The shear heating in the ductile regime and/or decompression and cooling associated with the exhumation of the CCB plausibly created favorable conditions for partial melting in the lower crustal LVZ.

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The Crustal Structure of the Eastern Marmara Region Using Receiver Function Analysis

10.5194/egusphere-egu2020-4689 ◽

2020 ◽

Author(s):

Pınar Büyükakpınar ◽

Mustafa Aktar

Keyword(s):

Fault Zone ◽

Receiver Function ◽

Function Analysis ◽

Joint Inversion ◽

Crustal Thickness ◽

Receiver Functions ◽

Gradual Transition ◽

Marmara Region ◽

The North ◽

Receiver Function Analysis

This study focuses on the crust of the Eastern Marmara in order to understand of how much the structure is influenced by the tectonic history and also by the activity of the NAF. Recent studies have claimed that the crustal thickness varies significantly on the north and south of the NAF, which is assumed to indicate the separation line between Eurasian and Anatolian Plates. The present study aims to reevaluate the claim above, using newly available data and recently developed tools. The methods used during the study are the receiver function analysis and surface wave analysis. The first one is more intensively applied, since the second one only serves to introduce stability constraint in the inversions. Data are obtained from the permanent network of KOERI and from PIRES arrays.&#160; The main result of the study indicates that the receiver functions for the stations close to the fault zone are essentially very different from the rest and should be treated separately. They show signs of complex 3D structures of which two were successfully analyzed by forward modeling (HRTX and ADVT). A dipping shallow layer is seen to satisfy the major part of the azimuthal variation at these two stations. For the stations off the fault on the other hand, the receiver functions show a more stable behavior and are analyzed successfully by classical methods. CCP stacking, H-k estimation, single and joint inversion with surface waves, are used for that purpose. The results obtained from these totally independent approaches are remarkably consistent with each other. It is observed that the crustal thickness does not vary significantly neither in the NS, nor in the SW direction. A deeper Moho can only be expected on two most NE stations where a gradual transition is more likely than a sharp boundary (SILT and KLYT). The structural trends, although not significant, are generally aligned in the EW direction.&#160; In particular, a slower lower crust is observed in the southern stations, which is possibly linked to the mantle upwelling and thermal transient of the Aegean extension. Otherwise neither the velocity, nor the thickness of the crust does not imply any significant variation across the fault zone, as was previously claimed.

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Role of dextral strike slip faulting in the distribution of Aegean extension since Miocene times inferred from receiver function analysis

10.5194/egusphere-egu2020-7529 ◽

2020 ◽

Author(s):

Agathe Faucher ◽

Christel Tiberi ◽

Frédéric Gueydan ◽

Alexandrine Gesret

Keyword(s):

Receiver Function ◽

Function Analysis ◽

Receiver Functions ◽

Strike Slip ◽

Point Of View ◽

Normal Faults ◽

The South ◽

Crustal Thinning ◽

Dextral Strike Slip

Aegean plate is marked since Eocene by widespread NE-SW extension induced by the African slab roll-back. In Miocene times, E-W shortening created by the westward Anatolian extrusion overlays the extension, with the formation of Miocene dextral strike slip faults in addition to normal faults. We propose to quantify the role of large dextral strike slip faults in accommodating Aegean extension, using receiver functions to image Moho geometry.Aegean extension is particularly evidenced by a topographic difference between the emerged continental Greece and the submerged Cyclades. In this study we characterize the associated Moho geometry with a particular focus on the transition between these two domains. From a geological point of view, the transition between continental Greece and the Cyclades is marked by two dextral strike slip faults: the Pelagonian fault (onshore) and the South Evvia fault (offshore). Our objective is also to show a potential Moho signature of these strike slip faults. &#160;We processed receiver functions (RF) from the MEDUSA stations located in Attic and Evvia.Our results show that the Moho is deeper beneath continental Greece (~27km) than beneath the Cyclades (~25km). A detailed azimuthal study of RF distribution shows a flat Moho underneath Continental Greece. The crustal thickness is also almost constant inside the Cyclades, as already suggested by previous studies. However, the transition between the Cyclades and Continental Greece is not continuous. These two crustal blocks are separated by the Pelagonian and the South Evvia strike slip faults in a narrow transition zone (~75km). In this zone (South Evvia/Attica), dip and strike of the Moho vary and suggest a crustal signature of the strike slip structures observed at the surface. These strike slip faults therefore accommodate in a narrow zone the inferred variations in crustal thicknesses between the Cyclades and Continental Greece.Our data show that differences in topography between Continental Greece and the Cyclades are isostatically compensated, reflecting various amount of crustal thinning larger in the Cyclades than in Continental Greece. Inside these two crustal blocks, we imaged a flat Moho, suggesting a wide rift extension process associated with the formation of numerous Miocene and Plio-Quaternary basins. &#160;The dextral strike slip faults at the edges of the continental blocks (Continental Greece and Cyclades) accommodated the inferred variations in the amount of crustal thinning, suggesting that they act as continental transfer zones at crustal-scale during Miocene Aegean Extension.

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Sp Receiver-Function Images of African and Arabian Lithosphere: Survey of Newly Available Broadband Data

Seismological Research Letters ◽

10.1785/0220190311 ◽

2020 ◽

Vol 91 (3) ◽

pp. 1813-1819 ◽

Cited By ~ 1

Author(s):

Lin Liu ◽

Siyou Tong ◽

Sanzhong Li ◽

Saleh Qaysi

Keyword(s):

Temporal Evolution ◽

Receiver Function ◽

Receiver Functions ◽

Plate Boundaries ◽

Data Set ◽

Seismic Stations ◽

Spatial Coverage ◽

Teleseismic Events ◽

Good Agreement

Abstract The growing quality and improving spatial coverage of broadband seismic stations on the African (Nubian + Somalian) and Arabian plates motivate us to present a catalog of S-to-P receiver functions (SRFs) from southern Africa to northern Arabia. As in North America where the ability to compare data from cratons to modern rift provinces has led to new insights about lithospheric discontinuities, so, too, in Africa and Arabia can we begin to track and study the Moho, midlithospheric discontinuities, and the lithosphere–asthenosphere boundary (LAB) between tectonothermal provinces and beneath plate boundaries. We utilized 1508 seismic stations recording 9349 teleseismic events to calculate 103,878 SRFs that we stacked in 1° circular bins. We find a robust positive arrival due to a seismic-wavespeed increase downward across the Moho in virtually all our stacked SRF traces at 15–55 km depth, and we verify this is in good agreement with previously published Ps results, thereby validating the quality of our data set. Our stacked SRF traces also show a sub-Moho negative arrival at a delay time equivalent to 50–132 km depth that should correspond to a negative velocity discontinuity at or above the LAB. Our continent-wide, plate-scale database offers the opportunity to explore for spatial and temporal evolution of lithospheric parameters.

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A reappraisal of the H–κ stacking technique: implications for global crustal structure

Geophysical Journal International ◽

10.1093/gji/ggz364 ◽

2019 ◽

Vol 219 (3) ◽

pp. 1491-1513 ◽

Cited By ~ 3

Author(s):

C S Ogden ◽

I D Bastow ◽

A Gilligan ◽

S Rondenay

Keyword(s):

Receiver Function ◽

Synthetic Data ◽

Flood Basalt ◽

Receiver Functions ◽

P Wave ◽

Frequency Content ◽

Data Set ◽

Numerical Result ◽

Lower Crustal ◽

Intrusion Layer

SUMMARY H–κ stacking is used routinely to infer crustal thickness and bulk-crustal VP/VS ratio from teleseismic receiver functions. The method assumes that the largest amplitude P-to-S conversions beneath the seismograph station are generated at the Moho. This is reasonable where the crust is simple and the Moho marks a relatively abrupt transition from crust to mantle, but not if the crust–mantle transition is gradational and/or complex intracrustal structure exists. We demonstrate via synthetic seismogram analysis that H–κ results can be strongly dependent on the choice of stacking parameters (the relative weights assigned to the Moho P-to-S conversion and its subsequent reverberations, the choice of linear or phase-weighted stacking, input crustal P-wave velocity) and associated data parameters (receiver function frequency content and the sample of receiver functions analysed). To address this parameter sensitivity issue, we develop an H–κ approach in which cluster analysis selects a final solution from 1000 individual H–κ results, each calculated using randomly selected receiver functions, and H–κ input parameters. 10 quality control criteria that variously assess the final numerical result, the receiver function data set, and the extent to which the results are tightly clustered, are used to assess the reliability of H–κ stacking at a station. Analysis of synthetic data sets indicates H–κ works reliably when the Moho is sharp and intracrustal structure is lacking but is less successful when the Moho is gradational. Limiting the frequency content of receiver functions can improve the H–κ solutions in such settings, provided intracrustal structure is simple. In cratonic Canada, India and Australia, H–κ solutions generally cluster tightly, indicative of simple crust and a sharp Moho. In contrast, on the Ethiopian plateau, where Palaeogene flood-basalts overlie marine sediments, H–κ results are unstable and erroneous. For stations that lie on thinner flood-basalt outcrops, and/or in regions where Blue Nile river incision has eroded through to the sediments below, limiting the receiver function frequency content to longer periods improves the H–κ solution and reveals a 6–10 km gradational Moho, readily interpreted as a lower crustal intrusion layer at the base of a mafic (VP/VS = 1.77–1.87) crust. Moving off the flood-basalt province, H–κ results are reliable and the crust is thinner and more felsic (VP/VS = 1.70–1.77), indicating the lower crustal intrusion layer is confined to the region covered by flood-basaltic volcanism. Analysis of data from other tectonically complex settings (e.g. Japan, Cyprus) shows H–κ stacking results should be treated cautiously. Only in regions of relatively simple crust can H–κ stacking analysis be considered truly reliable.

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The mantle flow below the Alps from isolated mantle anisotropy based on differential Ps – XKS Splitting

10.5194/egusphere-egu2020-2810 ◽

2020 ◽

Author(s):

Frederik Link ◽

Georg Rümpker

Keyword(s):

Receiver Function ◽

Function Analysis ◽

Receiver Functions ◽

Model Parameters ◽

Mantle Flow ◽

European Alps ◽

Crustal Anisotropy ◽

Axis Orientation ◽

The Alps ◽

Mantle Anisotropy

SKS-splitting measurements in the European Alps show an anisotropic fast axes parallel/subparallel relative to the mountain-belt. This indicates a mantle flow with a rotational component according to the orogeny under the assumption that the fast axes directly reflect the flow direction. This might be misleading due to a possible crustal contribution of anisotropy. Therefore, we isolate the crustal anisotropy using an improved receiver function method that accounts for anisotropic and structural properties.The analysis for the crustal anisotropy is based on the stacking method proposed by Kaviani & R&#252;mpker (2015). We modify their approach by introducing a time-selective splitting analysis of the crustal Ps- and PpPs-phases. The stacking is performed to the phases after correction of the anisotropic effect according to the model parameters H, the crustal thickness, &#160;&#954;, the P-to S-wave velocity ratio, a, the percentage of anisotropy and &#966;, the fast axis orientation.The Alps show a considerable Moho-topography due to its mountain root and its complex tectonic history. This can significantly deflect the crustal phases introducing a dominating appearance in the receiver functions. We therefore analyse for a dipping interface (not accounting for anisotropy) and then use an improved model in our analysis to infer the anisotropic properties of the crust.Knowing the crustal anisotropic contribution we correct for this effect on the XKS-waveforms to isolate the anisotropy of the mantle. The remaining splitting shows an improved approximation of the flow patterns in the asthenosphere, while complexities might still imply an effect of the lithospheric mantle.We apply our approach to stations of the AlpArray network resulting in a detailed distribution of the crustal anisotropy in the European Alps and show first results for the isolated mantle anisotropy from the corrected XKS-waveforms and the crustal anisotropy from the receiver-function analysis.

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Numerical experiments in broadband receiver function analysis

Bulletin of the Seismological Society of America ◽

10.1785/bssa0820031453 ◽

1992 ◽

Vol 82 (3) ◽

pp. 1453-1474

Author(s):

J. F. Cassidy

Keyword(s):

Numerical Experiments ◽

Arrival Time ◽

Receiver Function ◽

Function Analysis ◽

Forward Modeling ◽

Receiver Functions ◽

Resolving Power ◽

Earth Model ◽

The Earth ◽

Receiver Function Analysis

Abstract The use of broadband receiver function analysis to estimate the fine-scale S-velocity structure of the lithosphere is becoming increasingly popular. A series of numerical experiments shows several important aspects of this technique, with emphasis on estimation of dipping interfaces. The recent modification introduced to the receiver function analysis technique that preserves absolute amplitudes (Ammon, 1991) is more robust than the previous technique of modeling receiver functions that were normalized to unit amplitude. Using the latter method, shallow (e.g., depths less than ∼2 km) high-velocity contrast interfaces may alter the apparent amplitudes of Ps phases and produce inaccuracies in the Earth model developed. The use of absolute amplitudes minimizes this potential for error. When research targets include deep dipping structure, tight stacking bounds (e.g., ≦ 10° in backazimuth (BAZ) and epicentral distance (Δ)) should be applied to avoid attenuating Ps phases and to aid in the identification of reverberations or scattered energy. Reverberations sample a relatively large lateral range about the recording site (e.g., a radius of 1 to 1.5 times the depth of the reflecting interface) and in the presence of dipping interfaces exhibit drastic variations in amplitude and arrival time as a function of BAZ and Δ. Thus, they cannot readily be used to provide constraints on the Earth structure. Formal inversion techniques, which attempt to match all arrivals in the waveform, must be used with caution when modeling receiver functions from complex regions. Only those phases whose amplitude and arrival-time variations as a function of BAZ and Δ are consistent with those of Ps conversions should be modeled. Forward modeling may resolve, depending upon the data quality and noise level, S-velocity contrasts greater than ∼ 0.2 to 0.4 km / sec. Layers of thickness 2 to 5 km may be accurately imaged, and transition zones may be examined by considering various frequency bands of the data. In order to better understand the resolving power of the data, the averaging functions associated with the receiver functions may be calculated from the observed data and, if desired, used in the forward modeling process.

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Crustal and upper mantle seismic structure of the Svalbard Archipelago from the receiver function analysis

Polish Polar Research ◽

10.1515/popore-2015-0009 ◽

2015 ◽

Vol 36 (2) ◽

pp. 89-107 ◽

Cited By ~ 2

Author(s):

Monika Wilde−Piórko

Keyword(s):

Upper Mantle ◽

Barents Sea ◽

Receiver Function ◽

Function Analysis ◽

Seismic Station ◽

Receiver Functions ◽

Seismic Velocities ◽

Seismic Structure ◽

Svalbard Archipelago ◽

The North

Abstract Receiver function provides the signature of sharp seismic discontinuities and the information about the shear wave (S−wave) velocity distribution beneath the seismic station. This information is very valuable in areas where any or few reflection and/or refraction studies are available and global and/or regional models give only rough information about the seismic velocities. The data recorded by broadband seismic stations have been analysed to investigate the crustal and upper mantle structure of the Svalbard Archipelago. Svalbard Archipelago is a group of islands located in Arctic, at the north−western part of the Barents Sea continental platform, which is bordered to the west and to the north by passive continental margins. The new procedure of parameterization and selection of receiver functions (RFs) has been proposed. The back−azimuthal sections of RF show a strong variation for the HSPB and KBS stations. Significant amplitudes of transversal component of RF (T−RF) for the HSPB station indicate a shallow dipping layer towards the southwest. The structure of the crust beneath the SPITS array seems to be less heterogeneous, with very low amplitudes of converted phase comparing to the KBS and HSPB stations. Forward modelling by trial−and−error method shows a division of the crust into 3-4 layers beneath all stations and layering of the uppermost mantle beneath the SPITS array and the HSPB stations. The thickness of the mantle transition zone is larger for western part of archipelago and smaller for eastern part comparing to iasp91 model.

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Orientations of Broadband Stations of the KOERI Seismic Network (Turkey) from Two Independent Methods: P- and Rayleigh-Wave Polarization

Seismological Research Letters ◽

10.1785/0220200362 ◽

2021 ◽

Author(s):

Pınar Büyükakpınar ◽

Mustafa Aktar ◽

Gesa Maria Petersen ◽

Ayşegül Köseoğlu

Keyword(s):

Receiver Function ◽

Function Analysis ◽

Eastern Mediterranean ◽

Moment Tensor ◽

Eastern Mediterranean Region ◽

P Waves ◽

Data Set ◽

The North ◽

Correct Orientation ◽

Sensor Orientation

Abstract The correct orientation of seismic sensors is critical for studies such as full moment tensor inversion, receiver function analysis, and shear-wave splitting. Therefore, the orientation of horizontal components needs to be checked and verified systematically. This study relies on two different waveform-based approaches, to assess the sensor orientations of the broadband network of the Kandilli Observatory and Earthquake Research Institute (KOERI). The network is an important backbone for seismological research in the Eastern Mediterranean Region and provides a comprehensive seismic data set for the North Anatolian fault. In recent years, this region became a worldwide field laboratory for continental transform faults. A systematic survey of the sensor orientations of the entire network, as presented here, facilitates related seismic studies. We apply two independent orientation tests, based on the polarization of P waves and Rayleigh waves to 123 broadband seismic stations, covering a period of 15 yr (2004–2018). For 114 stations, we obtain stable results with both methods. Approximately, 80% of the results agree with each other within 10°. Both methods indicate that about 40% of the stations are misoriented by more than 10°. Among these, 20 stations are misoriented by more than 20°. We observe temporal changes of sensor orientation that coincide with maintenance work or instrument replacement. We provide time-dependent sensor misorientation correction values for the KOERI network in the supplemental material.

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