Moho Depth Map Research Articles

Structure of the crust-uppermost mantle beneath the Ethiopian volcanic province using ambient seismic noise and teleseismic P wave coda autocorrelation

The Ethiopian-Yemen plateaus have been affected by plume-related magmatism for at least 40 My, yet the nature and distribution of intrusive magmas and their relation to subsequent East Africa rifting remain poorly characterized. This paper presents a 3D shear (S) - wave velocity structure of the crust and uppermost mantle beneath the northern sectors of the East African rift and the dynamically-supported Ethiopian Plateau. We apply a Bayesian inversion of group and phase velocity dispersion curves for periods 5–40 s extracted from the ambient noise tomography of data from over 125 broadband seismic stations, and we identify seismic discontinuities using autocorrelation of P-wave coda. The resulting crustal structure affecting much of the Main Ethiopian Rift (MER) indicates a pronounced low S-wave velocity lower crust (∼3.6 km/s) that becomes thinner towards the northeast rising to almost the same depth level (∼20 km) as the base crust beneath the Afar triple junction zone. We also find high velocity features in the crust and uppermost mantle beneath the Afar rift axes, the current locus of strain and volcanism, that may indicate voluminous new basaltic crust. Our Moho-depth map indicates that the entire Afar Depression is underlain by crust thinner than 25 km, whereas the MER and central Ethiopian plateau are underlain by low S-wave velocity crust thicker than 35 km. These patterns suggest active underplating beneath the largely unfaulted plateau, in contrast to the efficient magmatic feeder system supplying a narrow zone of incipient seafloor spreading in the Afar depression. Within the uppermost mantle we report evidence of a localized asthenospheric upwelling beneath the western part of the plateau southeast of Lake Tana, overlying a cooled magma body within the upper crust. A broader low-velocity uppermost mantle underlies the crust beneath the Western Plateau. These observations attest to active mantle upwelling, heating, and melt intrusion at relatively different length scales beneath the plateau in agreement with the ongoing active strains reported away from the rift zones. At 45–60 km depth beneath the rift and its shoulders, we observe a fast lid (4.2–4.4 km/s). Beneath the plateau, upper mantle velocity highs that are at least 5 km below the Moho are observed. These areas have most likely experienced prolonged magma extraction and may mark highly depleted areas.

Crustal structure across the Central part of Narmada-Son Lineament, India based on the interpretation of aeromagnetic and gravity data: Geological implications

Narmada-Son Lineament (NSL) is a prominent geo-tectonic feature located in central India, characterised by complex geological structures and evolution history. In this study, we present a detailed joint interpretation of the aeromagnetic and gravity anomaly maps to delineate the crustal structure in order to address the thermo-tectonic activity below the NSL region. The NW-SE linear trend observed in the aeromagnetic anomaly map correlates well with the major tectonic elements of the NSL and the Vindhyan basin. The low-pass filtered regional gravity anomaly map and corresponding residual anomaly map revealed several crustal-scale structural features in the study area. The Curie depth map of the region prepared from the magnetic anomaly map shows the variation between 24-48 km. The corresponding heat flow map correlates well with the trends in surface heat flow data. The gravity-derived Moho depth map reveals that the values vary between 30-40 km in the NSL region with deeper Moho below the Vindhyan basin. Further, the crustal models obtained from the constrained potential field modelling for two long transects across the NSL in the present study area revealed i) the absence of crustal underplating in the eastern part of NSL below Hirapur-Mandla region, ii) the presence of mid-crustal horst like structure below NSL in both the transects, iii) undulating Moho with higher density crustal rocks within the NSL compared to the surrounding areas. The modelled crustal structure and the analysis of Curie depth as well as heat flow maps of the study area, reveal that the NSL region was affected by repeated tectonic activities since the Proterozoic times, and the present-day tectonics of this belt is greatly influenced by the reactivation of pre-existing faults along the NSL.

Ambient‐Noise Wave‐Equation Tomography of the Alps and Ligurian‐Provence Basin

AbstractTaking benefit of the AlpArray temporary network and permanent networks in W‐Europe, we construct a 3‐D onshore‐offshore velocity model of the crust and upper mantle using ambient‐noise wave‐equation tomography. We use a frequency‐dependent phase traveltime misfit function in an iterative procedure to refine a recent 3‐D Vs model computed from a Bayesian two‐step ambient noise tomography. Observed waveforms consist of vertical‐component noise correlations from 600 broadband stations in the Alps and surroundings, including ocean‐bottom seismometers in the Ligurian sea. We perform 3‐D inversion in the 5–85 s period range. In the long‐period band (20–85 s), an elastic approximation is considered, while in the 5–20 s band, we account for the effect of water layer in the Ligurian sea by applying a fluid‐solid coupling for acoustic‐elastic waveform simulations. The resulting Vs model enhances the shape and contrast of velocity structures, accounting for 3‐D and finite‐frequency effects. It emphasizes the deep sediments of the Ligurian‐Provence basin and focuses on the low‐velocity anomalies of the crust in the W‐Alps. We obtain a high‐resolution Moho depth map covering the Alps and Ligurian sea. In the W‐Alps, this map confirms the deepening of the European crust following the subduction beneath Adria and the existence of major structures such as the Moho jump beneath the external crystalline massifs and shallow depths associated with the Ivrea Body. It provides further constraints on the deep structure beneath the Ligurian‐Provence basin, regarding the lateral and along‐strike crustal‐thickness variations from the oceanic domain to the conjugate margins.

Review of tectonic inversion of sedimentary basins in NE and N Brazil: Analysis of mechanisms, timing and effects on structures and relief

Most intraplate areas worldwide are under compression characterized by thrust and strike-slip deformations. The sources of the stresses in these regions are a combination of far-field (regional) stresses (e.g., ridge push, slab pull, lithospheric drag) and near-field (local) stresses (e.g., topography, lateral and vertical anisotropy of strength or elastic properties, erosion, flexural bending, overloading, buoyancy of low-density regions). These intraplate regions are sites favorable for the tectonic inversion of sedimentary basins. Here, we review the tectonic inversions of the sedimentary basins in NE and N Brazil, which comprise a significant part of the South American intraplate (the South American Platform). These regions have been under compression since the Late Cretaceous. Reports of post-rift basin inversions derived from seismic profiles, fault-slip data, and topography have been described in the Sergipe-Alagoas, Paraíba, Potiguar, Ceará, Rio do Peixe, Araripe (NE Brazil), and Solimões (N Brazil) basins. Reports of inversions in the rift phase have also been described in the Araripe Basin. The present-day stress field indicates that inversions in NE Brazil can mainly be characterized as strike-slip and thrust fault regimes, whereas in N Brazil, inversions have occurred under reverse stress regimes. The most frequent inversion structures are reactivated faults, folds, and dome structures affecting the topography and the consequent uplift of rift and post-rift sedimentary units. Inversions have led to the reactivation of continental-scale structures, such as the strike-slip dextral shearing of the Transbrasiliano lineament, which affected rift and post-rift units in the Equatorial Margin of Brazil. The small crustal thickness of these areas favors inversion, as indicated by the most recent Moho depth map of South America. The interplay between far-field and near-field stresses explains the stress pattern in NE and N Brazil, where inversions have been observed.

New insights on Moho depth and regional lithospheric structure of central Oklahoma based on receiver function analysis from dense seismic networks

Knowledge of the midcontinent crustal structure of North America is crucial for understanding the evolutionary history of the ancient North American craton as Laurentia grew through accretion ∼1.5 Ga to 1 Ga. Although Oklahoma has been recognized as a tectonically stable region since the Phanerozoic, its crustal structure records the earlier formation of the Mazatzal and southern Granite-Rhyolite provinces 1.6 Ga to 1.4 Ga. We present results from teleseismic receiver function analysis applied to 221 events recorded on 169 broadband stations in central Oklahoma. Our findings include a Moho depth map of central Oklahoma based on stacked and depth-converted teleseismic P receiver functions. The results are interpreted together with gravimetric and magnetic datasets and a recently established seismic velocity model of the crust.The Moho map shows a generally flat crust-mantle boundary in central Oklahoma with an average depth of 43.5 km while we observe a sudden thickening on the crust of the northwestern part of Oklahoma where the Moho deepens to over 50 km depth. We also find a Mid-lithosphere discontinuity at the upper-most mantle in north-central Oklahoma, presented as a negative phase deepening southeastward from 60 km to 80 km. We further observe an intracrustal discontinuity at the Nemaha uplift and Anadarko shelf regions in a depth range of 17–30 km. The hypothesis of the Mid-continent Rift (MCR) extending into Oklahoma is examined in terms of the crustal structure and Moho depth variation revealed by receiver functions. We do not find evidence of Moho structure or lower-crustal underplay characteristics similar to what has been discovered in the northern part of MCR, but the intracrustal discontinuity that deepens towards the hypothesized MCR region suggests upper-crustal volcanics potentially caused by the extended expansion regime of the failed rift near the south-most termination.

Crustal Thickness Variations and Tectonic Settings in the Southwest Cameroon Inferred from Gravity and Topography Data

Abstract EIGEN 6C4 gravity anomalies are interpreted to determine the lateral and vertical variations in the crust and upper mantle structure and their influence on the isostasy of the coastal plain, transition zone between the Congo Craton (CC), the Pan-African Belt (PAB), and adjacent areas. The regional gravity anomalies have been inverted in an attempt to provide a Moho depth map. The inversion process was based on the Parker-Oldenburg method with a density contrast of 0.55 g/cm3 and an average depth reference of 39 km. In addition, various tests have been performed to validate the resulting Moho model and estimate the efficiency of the 3D gravity inversion by varying the density contrast for a fixed Moho reference depth. Inversion results reveal that the Moho depths generally agree with those obtained from previous geophysical studies. The computation of the isostatic models using the ETOPO1 digital elevation model (DEM) and its comparison with the Moho models obtained from gravity induce the following main conclusions: (1) an overcompensated crust beneath the coastal plain and the Yaounde Domain, (2) the crust beneath areas located in the southern end of the Adamawa-Yade Domain is thin and undercompensated, and (3) main volcanoes of the Southwestern Cameroon Volcanic Line (CVL) are isostatically undercompensated. This study also revealed that the local isostatic compensation law is not satisfied for most of the tectonic provinces of the study area, and we suggest alternative tectonic mechanisms to support topography below these tectonic features. Additionally, most seismic events (M>3.5) occurred in areas marked by abrupt changes in compensation amplitude. Thus, we concluded from this study that the northern limit of the CC, the Mount Cameroon, and its surroundings are tectonic extension areas that may play a crucial role in the occurrence of future earthquakes.

Crustal Thinning From Orogen to Back‐Arc Basin: The Structure of the Pannonian Basin Region Revealed by P‐to‐S Converted Seismic Waves

AbstractWe present the results of P‐to‐S receiver function analysis to improve the 3D image of the sedimentary layer, the upper crust, and lower crust in the Pannonian Basin area. The Pannonian Basin hosts deep sedimentary depocentres superimposed on a complex basement structure and it is surrounded by mountain belts. We processed waveforms from 221 three‐component broadband seismological stations. As a result of the dense station coverage, we were able to achieve so far unprecedented spatial resolution in determining the velocity structure of the crust. We applied a three‐fold quality control process; the first two being applied to the observed waveforms and the third to the calculated radial receiver functions. This work is the first comprehensive receiver function study of the entire region. To prepare the inversions, we performed station‐wise H‐Vp/Vs grid search, as well as Common Conversion Point migration. Our main focus was then the S‐wave velocity structure of the area, which we determined by the Neighborhood Algorithm inversion method at each station, where data were sub‐divided into back‐azimuthal bundles based on similar Ps delay times. The 1D, nonlinear inversions provided the depth of the discontinuities, shear‐wave velocities and Vp/Vs ratios of each layer per bundle, and we calculated uncertainty values for each of these parameters. We then developed a 3D interpolation method based on natural neighbor interpolation to obtain the 3D crustal structure from the local inversion results. We present the sedimentary thickness map, the first Conrad depth map and an improved, detailed Moho map, as well as the first upper and lower crustal thickness maps obtained from receiver function analysis. The velocity jump across the Conrad discontinuity is estimated at less than 0.2 km/s over most of the investigated area. We also compare the new Moho map from our approach to simple grid search results and prior knowledge from other techniques. Our Moho depth map presents local variations in the investigated area: the crust‐mantle boundary is at 20–26 km beneath the sedimentary basins, while it is situated deeper below the Apuseni Mountains, Transdanubian and North Hungarian Ranges (28–33 km), and it is the deepest beneath the Eastern Alps and the Southern Carpathians (40–45 km). These values reflect well the Neogene evolution of the region, such as crustal thinning of the Pannonian Basin and orogenic thickening in the neighboring mountain belts.

A two-dimensional lithospheric magnetic anomaly field model of Egypt using the measurements from Swarm satellites

We use magnetic field data observed by the Swarm mission from 2014 to 2020 to construct, for the first time, a two-dimensional (2D) lithospheric magnetic anomaly model of Egypt and its surrounding area. Nighttime data during quiet geomagnetic conditions has been expanded in terms of the Legendre polynomial in harmonic terms N = 6–50. The damped least square method has been used to estimate the model coefficients based on the lithospheric magnetic data. Modeled data at two different altitudes (438–448 km and 503–511 km) were compared with the CHAOS model. Results exhibit that the 2D model is superior to the CHAOS model in the capability of extracting more information about small-scale crustal anomaly field. At low altitudes (438–448 km), the strength of the anomaly field increases, but the noise of the external fields has greatly reduced at high altitudes (503–511 km). Besides, the magnetic anomaly field at low altitudes has illuminated short-scale anomalies that didn't appear at high altitudes. Both the total and vertical magnetic anomaly vectors showed their ability to reveal tectonic structures compared with Moho depth map and the geological maps.

High-Resolution Crustal S-wave Velocity Model and Moho Geometry Beneath the Southeastern Alps: New Insights From the SWATH-D Experiment

We compiled a dataset of continuous recordings from the temporary and permanent seismic networks to compute the high-resolution 3D S-wave velocity model of the Southeastern Alps, the western part of the external Dinarides, and the Friuli and Venetian plains through ambient noise tomography. Part of the dataset is recorded by the SWATH-D temporary network and permanent networks in Italy, Austria, Slovenia and Croatia between October 2017 and July 2018. We computed 4050 vertical component cross-correlations to obtain the empirical Rayleigh wave Green’s functions. The dataset is complemented by adopting 1804 high-quality correlograms from other studies. The fast-marching method for 2D surface wave tomography is applied to the phase velocity dispersion curves in the 2–30 s period band. The resulting local dispersion curves are inverted for 1D S-wave velocity profiles using the non-perturbational and perturbational inversion methods. We assembled the 1D S-wave velocity profiles into a pseudo-3D S-wave velocity model from the surface down to 60 km depth. A range of iso-velocities, representing the crystalline basement depth and the crustal thickness, are determined. We found the average depth over the 2.8–3.0 and 4.1–4.3 km/s iso-velocity ranges to be reasonable representations of the crystalline basement and Moho depths, respectively. The basement depth map shows that the shallower crystalline basement beneath the Schio-Vicenza fault highlights the boundary between the deeper Venetian and Friuli plains to the east and the Po-plain to the west. The estimated Moho depth map displays a thickened crust along the boundary between the Friuli plain and the external Dinarides. It also reveals a N-S narrow corridor of crustal thinning to the east of the junction of Giudicarie and Periadriatic lines, which was not reported by other seismic imaging studies. This corridor of shallower Moho is located beneath the surface outcrop of the Permian magmatic rocks and seems to be connected to the continuation of the Permian magmatism to the deep-seated crust. We compared the shallow crustal velocities and the hypocentral location of the earthquakes in the Southern foothills of the Alps. It revealed that the seismicity mainly occurs in the S-wave velocity range between ∼3.1 and ∼3.6 km/s.

Lateral variation in Moho depth around the southern Tanlu fault zone and its adjacent area

We estimated Moho depth beneath the southern Tanlu fault zone and its adjacent area using common-conversion-point (CCP) stacking of receiver functions, which were computed from teleseismic records of the CEArray. Our estimated Moho depth matches well with 2-D profiles derived from active-source deep seismic reflection surveys, suggesting that the calculated the Moho depth map is likely accurate beyond the 2-D profiles. Overall, the estimated Moho depth map showed a high spatial correlation with tectonic provinces, i.e., Moho topographic boundaries are in good agreement with geological boundaries. Beneath the Dabie orogenic belt and the mountainous areas in southern Anhui Province, the Moho lies relatively deep, and there is an obvious difference in Moho depth between the two sides of this segment of the Tanlu fault. We further selected four depth profiles with dense instrumentation to show Moho depth changes across different tectonic blocks in the study area. We saw two step-like changes in Moho depth beneath the Xiangfan-Guangji and Gushi-Feizhong, which run parallel along the WNW-ESE direction and delineate the southern and northern bounds of the northern Dabie orogenic belt, which is likely the suture zone between the North China Block and South China Block. Crust beneath the northeast corner of the study area is significantly thinner than other areas, which is consistent with the crustal detachment model proposed for suturing between the North and South China blocks in the region east to the Tanlu fault.

Moho depth map of northern Venezuela based on wide-angle seismic studies

As part of the lithosphere, the crust represents Earth's rigid outer layer. Some of the tools to study the crust and its thickness are wide-angle seismic studies. To date, a series of seismic studies have been carried out in Venezuela to determine in detail the crustal thickness in the southern Caribbean, in the region of the Caribbean Mountain System in northern Venezuela, as well as along the Mérida Andes and surrounding regions. In this study, a review of the wide-angle seismic data is given, incorporating new data from the GIAME project for western Venezuela, resulting in a map of Moho depth north of the Orinoco River, which serves as the basis for future integrated models. Differences in Moho depths from seismic data and receiver function analysis are discussed. From the Caribbean plate, Moho depth increases from 20 to 25 km in the Venezuela Basin to about 35 km along the coast (except for the Falcón area where a thinning to less than 30 km is observed) and 40–45 km in Barinas - Apure and Guárico Basins, and Guayana Shield, respectively. Values of more than 50 km are observed in the Maturín Basin and in the southern part of the Mérida Andes.

Imaging Alpine crust using ambient noise wave-equation tomography

SUMMARYWe present an improved crustal Vs model and Moho depth map using ambient noise wave-equation tomography. The so-called ‘ambient noise wave-equation tomography’ is a method to invert seismic ambient noise phase dispersion data based on elastic waveform simulation, which accounts for 3-D and finite-frequency effects. We use cross-correlations of up to 4 yr of continuous vertical-component ambient seismic noise recordings from 304 high-quality broad-band stations in the Alpine region. We use model LSP_Eucrust1.0 obtained from traditional ambient noise tomography as initial model, and we iteratively improve the initial model by minimizing frequency-dependent phase traveltime differences between the observed and synthetic waveforms of Rayleigh waves in the period range 10–50 s. We obtain the final model after 15 iterations with ∼65 per cent total misfit reduction compared to the initial model. At crustal depth, the final model significantly enhances the amplitudes and adjusts the shapes of velocity anomalies. At Moho and upper-mantle depth, the final model corrects an obvious systematic velocity shift of the initial model. The resulting isovelocity Moho map confirms a Moho step along the external side of the external crystalline massifs of the northwestern Alps and reveals underplated gabbroic plutons in the lower most crust of the central and eastern Alps. Ambient noise wave-equation tomography turns out to be a useful tool to refine shear wave velocity models obtained by traditional ambient noise tomography based on ray theory.

Crustal Thickness Beneath the Dinarides and Surrounding Areas From Receiver Functions

AbstractKnowledge about the crustal thickness is one of the key elements in the reconstruction of the regional tectonic history. The Dinaric mountain belt is one of the most enigmatic segments of the Alpine‐Mediterranean collision zone, characterized by large variations in crustal thickness and not studied sufficiently. We present a new Moho depth map for the wider Dinarides region which was created using teleseismic earthquake recordings from 87 permanent and temporary seismic stations in the region. Teleseismic data were analyzed using the receiver function method to extract converted P to S waves.The resulting Moho topography fits well within a structural framework comprising a thicker crust under the Dinarides, which gradually becomes thinner toward the Pannonian and Adriatic domains. The profiles crossing the northwestern Dinarides are marked by a relatively sharp decrease in crustal thickness north of the main thrust front. This transition is followed by significant crustal thinning toward the Pannonian basin. The Mohorovičić discontinuity lies the deepest in the central and southern Dinarides, at depths of over 55 km. Here similarly to the northwestern segment we observe a jump in the crustal thickness when transitioning toward the Internal Dinarides, which hints at possible underthrusting (or subduction) of the Adria plate in this region. Moho depths in the transition zone toward the Pannonian basin and in the Pannonian basin proper vary between 25 and 35 km. In the Adriatic domain, we find crustal thickness ranging from 30 km to more than 45 km around the Central Adriatic islands.

A new 3-D P-wave velocity model for the Gulf of Cadiz and adjacent areas derived from controlled-source seismic data: application to nonlinear probabilistic relocation of moderate earthquakes

SUMMARYThe SW Iberian margin is well known for its complex tectonic setting and crustal structure and by the occurrence of moderate magnitude earthquakes and some great tsunamigenic earthquakes. Fortunately, many seismic reflection and refraction profiles have been carried out, providing detailed information about the crustal structure of the main geologic domains in this region. These studies show a first-order variation due to the transition from oceanic to continental domain, large-scale heterogeneities within the crust and an irregular Moho topography. Routine earthquake locations in this area have been usually computed using a general 1-D velocity model which is clear that cannot account for such a heterogeneous structure. In addition, regional seismic stations used to locate the Gulf of Cadiz seismicity are on land and far away to the east, implying large azimuthal gaps and distances. In this context, a 3-D approach seems necessary to properly solve the crustal velocity field and improve earthquake location in this area. With this purpose, we present a new digital 3-D P-wave velocity distribution for the crust and uppermost mantle derived from previously published controlled-source seismic experiments carried out in SW Iberia and the Gulf of Cadiz over the last 40 yr. We have reviewed more than 50 wide-angle and multichannel seismic reflection and refraction profiles and digitized the most significant published 2-D seismic velocity models, performing an updated compilation of crustal parameters (P-wave velocities and geometry and depth of the main crustal interfaces). These velocities as a function of position and depth have been interpolated using ordinary kriging algorithm to obtain, in the form of a regular georeferenced 20 × 20 × 1 km grid spacing, a high-resolution 3-D P-wave velocity distribution for the crust and uppermost mantle and a continuous Moho depth map of the whole area of this study (33°N–41°N latitude and 15°W–5°W longitude). Since current seismic location tools allow the implementation of 3-D grid structures, we have applied our 3-D model to relocate a selection of moderate earthquakes occurred in the studied region using a probabilistic nonlinear method. In the Gulf of Cadiz area the probabilistic approximation provides maximum likelihood hypocentres located within the uppermost mantle with the majority of depths ranging between 20 and 45 km. This model would subsequently be implemented at the Spanish Seismic Network for the routine relocation of the seismicity of the area.

Modeling Satellite Gravity Gradient Data to Derive Density, Temperature, and Viscosity Structure of the Antarctic Lithosphere

AbstractIn this study we combine seismological and petrological models with satellite gravity gradient data to obtain the thermal and compositional structure of the Antarctic lithosphere. Our results indicate that Antarctica is largely in isostatic equilibrium, although notable anomalies exist. A new Antarctic Moho depth map is derived that fits the satellite gravity gradient anomaly field and is in good agreement with independent seismic estimates. It exhibits detailed crustal thickness variations also in areas of East Antarctica that are poorly explored due to sparse seismic station coverage. The thickness of the lithosphere in our model is in general agreement with seismological estimates, confirming the marked contrast between West Antarctica (<100 km) and East Antarctica (up to 260 km). Finally, we assess the implications of the temperature distribution in our model for mantle viscosities and glacial isostatic adjustment. The upper mantle temperatures we model are lower than obtained from previous seismic velocity studies. This results in higher estimated viscosities underneath West Antarctica. When combined with present‐day uplift rates from GPS, a bulk dry upper mantle rheology appears permissible.

GIGJ: A Crustal Gravity Model of the Guangdong Province for Predicting the Geoneutrino Signal at the JUNO Experiment

AbstractGravimetric methods are expected to play a decisive role in geophysical modeling of the regional crustal structure applied to geoneutrino studies. GIGJ (GOCE Inversion for Geoneutrinos at JUNO) is a 3‐D numerical model constituted by ~46 × 103 voxels of 50 × 50 × 0.1 km, built by inverting GOCE (Gravity field and steady‐state Ocean Circulation Explorer) gravimetric data over the 6° × 4° area centered at the JUNO (Jiangmen Underground Neutrino Observatory) experiment, currently under construction in the Guangdong Province (China). The a priori modeling is based on the adoption of deep seismic sounding profiles, receiver functions, teleseismic P wave velocity models, and Moho depth maps, according to their own accuracy and spatial resolution. The inversion method allowed for integrating GOCE data with the a priori information and some regularization conditions through a Bayesian approach and a stochastic optimization. GIGJ fits the highly accurate and homogeneously distributed GOCE gravity data with a ~1 mGal standard deviation of the residuals, compatible with the observation accuracy. GIGJ provides a site‐specific subdivision of the crustal layers masses, of which uncertainties include estimation errors, associated to the gravimetric solution, and systematic uncertainties, related to the adoption of a fixed sedimentary layer. A consequence of this local rearrangement of the crustal layer thicknesses is a ~21% reduction and a ~24% increase of the middle and lower crust geoneutrino signal, respectively. The geophysical uncertainties of geoneutrino signals at JUNO produced by unitary uranium and thorium abundances distributed in the upper, middle, and lower crust are reduced by 77%, 55%, and 78%, respectively. The numerical model is available at this site (http://www.fe.infn.it/radioactivity/GIGJ).

Mapping the Alaskan Moho

Research Article| October 10, 2018 Mapping the Alaskan Moho Meghan S. Miller; Meghan S. Miller aAustralian National University, Research School of Earth Sciences, Building 142 Mills Road, Canberra, Australian Capital Territory 2601, Australia, meghan.miller@anu.edu.au Search for other works by this author on: GSW Google Scholar Louis Moresi Louis Moresi bUniversity of Melbourne, School of Earth Sciences, Parkville, Victoria 3010, Australia Search for other works by this author on: GSW Google Scholar Seismological Research Letters (2018) 89 (6): 2430–2436. https://doi.org/10.1785/0220180222 Article history first online: 10 Oct 2018 Cite View This Citation Add to Citation Manager Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation Meghan S. Miller, Louis Moresi; Mapping the Alaskan Moho. Seismological Research Letters 2018;; 89 (6): 2430–2436. doi: https://doi.org/10.1785/0220180222 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietySeismological Research Letters Search Advanced Search ABSTRACT We present a series of Moho depth maps for the Alaskan region based on P receiver function estimates using data from all available broadband instrumentation from 1999 to April 2018 including the USArray Transportable Array. The average Moho depths beneath individual broadband stations are presented first as spot measurements and then used to produce a series of interpolated smooth surfaces by an adaptive triangulation process followed by the fitting of a bicubic spline. The interpolated surfaces include a measure of confidence in the interpolation and can be used to assess and determine a preferred model. The resulting Moho depth map (single continuous surface) provides a reasonable estimate of the Earth’s outermost layer thickness beneath Alaska as constrained by receiver functions for use in applications such as tomography, regional‐scale interpretations, or simulations of seismic waves. The models are provided as a python module with examples in the form of jupyter notebooks. Our original workflow is provided to allow updates to this dataset or use with other similar datasets. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

The refined Moho depth map in the Carpathian-Pannonian region

We present a new digital Moho depth map of the Carpathian-Pannonian region. The map was produced by compiling Moho discontinuity depth data, which were obtained by interpretation of seismic measurements taking into account the results of 2-D and 3-D integrated geophysical modelling. The resultant map is characterized by significant Moho-depth variations. The trends and features of the Moho in this region were correlated with tectonic units.

Moho depth determination beneath the Zagros Mountains from 3D inversion of gravity data

Due to its geological and economic importance, the Zagros Mountains have been investigated by many researchers during the last decades. Nevertheless, in spite of all the studies conducted on the region, there are still some controversial problems concerning the structure of the Zagros Mountains, including crustal depths, demanding more insights into understanding the crustal constraints of the region. Accordingly, we have conducted a gravity study to determine Moho depth map of the Zagros Mountains region, including its major structural domains from the coastal plain of the Persian Gulf to central Iran. The employed data are the densest and most accurate terrestrial gravity data set observed until now with the precision of 5 μGal and resolution of 5 arc-minute by 5 arc-minute. To image Moho depth variations, gravity inversion software GROWTH2.0 is used, proposing the possibility to model stratified structures by means of a semi-objective exploratory 3D inversion approach. The obtained results reveal the crustal thickness of ~ 30–35 km underneath the southwestern most Zagros Fold-Thrust Belt increasing northeastward to 48 km. The maximum Moho depth is estimated ~ 62 km below the Zagros Mountains belt along the Main Zagros Thrust. Northeast of the study area, an average crustal thickness of 46 km is computed beneath Urumieh–Dokhtar magmatic arc and central Iran.

Moho topography beneath the Iberian-Western Mediterranean region mapped from controlled-source and natural seismicity surveys

The complex tectonic interaction processes between the European and African plates at the Western Mediterranean have left marked imprints in the crustal architecture of this area, particularly concerning the lateral variations in crustal thicknesses. The detailed mapping of such variations is hence of large interest, as it provides a major constraint to geophysical and geodynamic modeling at different scales. Controlled-source seismic profiling and receiver functions from natural seismicity are widely considered as major tools to constrain Moho topography. We compile here the Moho depths determined from a comprehensive number of both types of seismic surveys, to end up with a new 3D Moho depth map of the Iberian Peninsula, its continental margins and North Morocco. Since the 1970s, the lithospheric structure beneath this study area has been extensively investigated using multichannel normal incidence seismic reflection and refraction/wide-angle reflection profiling. In the last few years some high-resolution surveys at sea and inland have been acquired, the latter ones involving ~1000 land stations. On the other hand, the TopoIberia-IberArray experiment has triggered the investigations on crustal and lithospheric structure using natural seismicity, providing a homogeneous spatial resolution never achieved before. The availability of good quality results from both methodologies in a common area provides an excellent opportunity to check the consistency of the Moho depth estimations. The integration of both datasets has resulted in a new, high resolution map of the crustal thickness variations. The final grid evidences large Moho topography variations, including crustal imbrication in the Pyrenean range, a large and relatively undisturbed Variscan Massif in the center of Iberia and a probable delamination process beneath the Gibraltar Arc. The crustal thicknesses vary from ~15km in continental margins up to values exceeding 50km beneath the Pyrenees or the Rif Cordillera.