Moho depth determinations based on spectral-ratio analysis of NORSAR long-period P waves

Berteussen, K. A.

doi:10.1016/0031-9201(77)90006-1

Cited by 157 publications

(97 citation statements)

References 10 publications

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“…The starting model used in the joint inversions consisted of an isotropic medium with a 35.5-km-thick crust and a linear shearwave-velocity increase across the crust of 3.4-4.0 km s -1 , overlying a flattened PREM (Preliminary Reference Earth Model) structure for the mantle (Dziewonski & Anderson 1981). The crustal Poisson's ratio was set to the value obtained from the H-κ stacking at each station and crustal densities were obtained from the values of Vp using the empirical relationship of Berteussen (1977). The preset thicknesses of the first and second layers were, respectively, 1 and 2 km, and the layer thickness increased to 2.5 km for depths between 3 and 60.5 km, 5 km for depths between 60.5 and 260.5 km, and 10 km below 260.5 km depth.…”

Section: Joint Inversion Of Receiver Functions With the Dispersion Ofmentioning

confidence: 99%

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The structure of the crust and uppermost mantle beneath Madagascar

Andriampenomanana

Nyblade

Wysession

et al. 2017

Geophysical Journal International

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S U M M A R YThe lithosphere of Madagascar was initially amalgamated during the Pan-African events in the Neoproterozoic. It has subsequently been reshaped by extensional processes associated with the separation from Africa and India in the Jurassic and Cretaceous, respectively, and been subjected to several magmatic events in the late Cretaceous and the Cenozoic. In this study, the crust and uppermost mantle have been investigated to gain insights into the present-day structure and tectonic evolution of Madagascar. We analysed receiver functions, computed from data recorded on 37 broad-band seismic stations, using the H-κ stacking method and a joint inversion with Rayleigh-wave phase-velocity measurements. The thickness of the Malagasy crust ranges between 18 and 46 km. It is generally thick beneath the spine of mountains in the centre part (up to 46 km thick) and decreases in thickness towards the edges of the island. The shallowest Moho is found beneath the western sedimentary basins (18 km thick), which formed during both the Permo-Triassic Karro rifting in Gondwana and the Jurassic rifting of Madagascar from eastern Africa. The crust below the sedimentary basin thickens towards the north and east, reflecting the progressive development of the basins. In contrast, in the east there was no major rifting episode. Instead, the slight thinning of the crust along the east coast (31-36 km thick) may have been caused by crustal uplift and erosion when Madagascar moved over the Marion hotspot and India broke away from it. The parameters describing the crustal structure of Archean and Proterozoic terranes, including average thickness (40 km versus 35 km), Poisson's ratio (0.25 versus 0.26), average shear-wave velocity (both 3.7 km s -1 ), and thickness of mafic lower crust (7 km versus 4 km), show weak evidence of secular variation. The uppermost mantle beneath Madagascar is generally characterized by shear-wave velocities typical of stable lithosphere (∼4.5 km s -1 ). However, markedly slow shear-wave velocities (4.2-4.3 km s -1 ) are observed beneath the northern tip, central part and southwestern region of the island where the major Cenozoic volcanic provinces are located, implying the lithosphere has been significantly modified in these places.

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Section: Joint Inversion Of Receiver Functions With the Dispersion Ofmentioning

confidence: 99%

“…Poisson's ratio was set to 0.35 for the top 3 km and then 0.29 for the remaining 7 km. Again, the densities were determined using the velocity-density relationship from Berteussen (1977).…”

Section: Joint Inversion Of Receiver Functions With the Dispersion Ofmentioning

confidence: 99%

The structure of the crust and uppermost mantle beneath Madagascar

Andriampenomanana

Nyblade

Wysession

et al. 2017

Geophysical Journal International

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“…At greater depths we use the P velocity structure interpreted for the southern half of the VISP line by Drew and . The P velocity models were converted to S velocities using Poisson's ratio estimates from earthquake [Berteussen, 1977].…”

Section: Data Processing and Analysismentioning

confidence: 99%

The northern limit of the subducted Juan de Fuca Plate system

Cassidy¹,

Ellis²,

Karavas³

et al. 1998

J. Geophys. Res.

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Abstract. Analysis of data recorded at an array of three-component broadband seismograph stations deployed on northern Vancouver Island and the adjacent British Columbia mainland, at the northern end of the Cascadia subduction zone, provides the first constraints on the S wave velocity structure of this region and permits us to define the northern limit of the subducted Juan de Fuca plate system. During a 2-year period, more than 80 teleseisms were recorded at our five stations. The method of receiver function analysis was used to constrain the S velocity structure to upper mantle depths. Beneath the northern three stations, a relatively simple continental crust is interpreted with a well-defined Moho near 37-39 km depth. An upper crustal S velocity discontinuity at these stations is interpreted as the top of the high-velocity rocks of the Wrangellia terrane. In contrast, more complicated structure dominated by pronounced low-velocity zones dipping to the NE are interpreted beneath our southern two stations. The shallower low-velocity zone is 6-8 km thick, has an S velocity contrast of 0.6-1.1 krn/s, and lies within the continental crust. This feature is similar to a pronounced lowvelocity layer (the E zone) imaged beneath southern Vancouver Island. The deeper low-velocity zone is interpreted as the subducted oceanic crust. We interpret the pronounced change in S velocity structure that we observe as the northern limit of the subducted oceanic plate beneath Vancouver Island. This change coincides with significant changes in topography, heat flow, gravity, and geochemistry.

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“…The Vp/Vs has been assumed as~2.0, 1.73 and 1.8 for velocities in the sediments, consolidated crust and the mantle, respectively. The density was calculated from Vp from combined formulas of Gardner et al (1974) and Berteussen (1977). The characteristic feature of the structure beneath each station was a very thin layer of 500, 300 and 200 meters width and very low Vs equal to 1.4, 0.9 and 0.8 km s −1 as− sociated with poorly consolidated ground, respectively for the KBS and HSPB sta− tions and the SPITS array.…”

Section: Modelling and Resultsmentioning

confidence: 99%

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

Wilde−Piórko¹

2015

Polish Polar Research

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Abstract:Receiver function provides the signature of sharp seismic discontinuities and the information about the shear wave (S−wave) velocity distribution beneath the seismic sta− tion. 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 continen− tal 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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Moho depth determinations based on spectral-ratio analysis of NORSAR long-period P waves

Cited by 157 publications

References 10 publications

The structure of the crust and uppermost mantle beneath Madagascar

The structure of the crust and uppermost mantle beneath Madagascar

The northern limit of the subducted Juan de Fuca Plate system

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

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