The composition of the Earth's core and mantle is set by the chemical equilibrium between metals and silicates during core/mantle segregation. The metallic core separated from the mantle by gravitational descent in the form of diapirs in a magma ocean, and therefore the dynamics of the diapir's downward movement has an influence on the chemical equilibrium. In this study, we characterize the descent

Various models have been proposed for the destruction of the Eastern North China Craton (NCC); however, it is still a highly controversial scientific issue. In this study, abundant teleseismic data recorded by permanent and temporary stations in the NCC were collected, and P-wave tomography and common conversion point (CCP) stacking of receiver functions were performed. The results from this study

A thick Infra-Cambrian to Phanerozoic sedimentary sequence in eastern Arabia conceals a poorly known Neoproterozoic basement that once separated the currently exposed Arabian Shield (western Arabia) from NW India in Gondwana. In this study, the Arabian Platform (eastern Arabia) is targeted by relatively high-resolution passive-source seismic tomography for the first time, which aims to illuminate crust

The 2012 Mw 8.6 Indian Ocean earthquake, the largest instrumentally recorded strike-slip event, has been described as a westward rupture on orthogonal faults that are part of the original oceanic fabric of the region. Reported estimates of its depth vary from 10 to 45 km, while the maximum depth of its inferred rupture extends to ~50–60 km. The complexity of the earthquake is undeniable both in terms

Electrical conductivity of alkali-rich silicate melts is less well known than for subalkaline melts. This work experimentally determined the electrical conductivity of shoshonitic (potassium-rich trachyandesitic) melts at 1073–1823 K and 0.5–1.8 GPa with H2O content up to 2.6 wt% in a piston cylinder apparatus. The activation volume (~8.5 cm3/mol) which characterizes pressure effect is at the lower

In the lower part of the mantle transition zone, seismic polarization anisotropies, which could be caused by the lattice preferred orientation (LPO) of elastically anisotropic minerals, were observed related with subducted materials. Stishovite, which is one of the dominant minerals in mid-ocean ridge basalt, continental crust and sediment layers, possesses significant anisotropic elasticity and has

The dynamo effect is the most popular candidate to explain the non-primordial magnetic fields of astrophysical objects. Although many systematic studies of parameters have already been made to determine the different dynamical regimes explored by direct numerical geodynamo simulations, it is only recently that the regime corresponding to the outer core of the Earth characterized by a balance of forces

Seismic recordings from the USArray of the October 1, 2013 Sea of Okhotsk earthquake and the May 24, 2010 Western Brazil earthquake include high-amplitude SxP signals due to S-wave to P-wave scattering about 150 to 200 km below the 660-km discontinuity below these events. The scattering structures have been mapped previously and interpreted as fragments of folded crust that subducted into the uppermost

The south Indian shield, primarily consisting of Archean cratons and Cretaceous-Tertiary Deccan Volcanic Province (DVP), has undergone several major tectonic episodes during its evolution. The Deccan volcanism at Cretaceous-Tertiary (~65 Ma) is the last major tectono-thermal event, which influenced a substantial part of the south Indian shield. To understand the influence of the Deccan volcanism on

Although previous tomographic studies found a large low S-velocity province (LLSVP) in the lowermost mantle beneath the Pacific, due to a lack of resolution it remains unclear whether the LLSVP consists of clusters of small-scale low-velocity anomalies or large-scale anomalies. We recently deployed a seismic-array in Thailand which provides a dataset with wide azimuthal coverage at the western Pacific

This study focused on the earthquake network properties of Southern California. The event synchronization method was used to create an earthquake network of the aforementioned region. Local network measurements were utilized to investigate the most active and prominent subregions and their effects on the earthquake dynamics of the region. These measurements showed that two regions (the Eastern California

Anisotropy of magnetic susceptibility (AMS) fabrics have been studied for the first time on a well constrained Paleoproterozoic Bangalore-Karimnagar giant mafic dyke swarm at ca. 2367 Ma in the Dharwar craton, south India. A total number of 43 samples from nine sites representing five N-E trending dykes have been subjected to AMS and conventional rock magnetic studies. The magnetic fabric is principally

The earthquake coda is the residual vibration energy long after the main arrivals of an earthquake. Previous studies of coda waves have focused on high frequencies and small earthquakes, which are generally attributed to the scattering from the Earth's internal heterogeneities. Here we examined the early coda of great earthquakes at long periods (50 to 300 s) at time window of 10,000 to 50,000 s after

To decipher possible crustal modifications associated with complex tectonics in SE Asia, we have conducted a systematic receiver function investigation beneath the central Sunda plate mainly including Borneo, the Malay Peninsula, Sumatra and part of the South China Sea (SCS). Well-determined observations from a total of 22 stations reveal a laterally heterogeneous crust with thickness ranging from

Thermal structure of the lithosphere exerts a primary control on its strength and density and thereby its dynamic evolution as the outer thermal and mechanic boundary layer of the convecting mantle. This contribution focuses on continental lithosphere. We review constraints on thermal conductivity and heat production, geophysical and geochemical/petrological constraints on thermal structure of the

The 1896 high-quality relative travel-time residuals are collected by applying the Multi-Channel Cross-Correlation technique to the waveform data of teleseismic events recorded by a short-period dense seismic array consisting of 302 stations in the Weifang segment of the Tanlu fault zone. Using the Fast Marching Teleseismic Tomography technique, these residuals are inverted for a fine P-wave crustal

The southeastern (SE) Tibetan plateau is uplifting accompanying strong seismicity, but the relationship between the crustal structure and tectonic process in this region is still unclear. Seismic anisotropy provides important clues for the deformation mechanism. Here we applied the harmonic decomposition approach and further conducted a Markov-Chain-Monte-Carlo (MCMC) inversion to analyze the crustal

A new approach to the interpretation of magnetic anomalies generated by geological structures resembling simple geometrical bodies is presented. The method is based on the Genetic-Price hybrid Algorithm (GPA) recently proposed by the authors for the inversion of potential-field data, specifically of self-potential signals. In this paper, the effectiveness of the proposed algorithm is tested on magnetic

Significant diversity in the Indian lithosphere is seen in 3-D shear wave velocity images inverted from the dispersion of group velocities measured from ambient noise and earthquake waveforms along 21,600 paths. Velocity models constructed at 1° intervals to a depth of 200 km suggest a bipolar nature of the Indian lithosphere. We observe a two layer lithospheric mantle beneath the eastern Peninsular

The measurement of anhysteretic remanent magnetization (ARM) is an easy nondestructive means of evaluating many important rock properties. This involves applying an alternating magnetic field (AF) along with a direct biasing field (DF) to magnetize rock samples. Various techniques employing ARM have been widely used with notable success to help solve problems in tectonics, volcanology, sedimentology

Mount Erebus, Antarctica, has a persistent lava lake with Strombolian eruptions. Volcanic eruptions can be automatically detected with multiple methods such as cross-correlation of seismic recordings and identifying anomalies in gas emissions. We demonstrate a new method of detecting Strombolian eruptions by training a convolutional neural network to automatically categorize eruptions in infrared images

The seismic velocities of ferric iron-enriched bridgmanite under core-mantle boundary (CMB) conditions were calculated using GGA + U ab initio molecular dynamics to probe whether ferric iron enriched mantle can explain the properties of ultra-low velocity zones (ULVZ). Under these conditions ferric iron demonstrated some unusual properties. The effect of ferric iron on the 0 K transition pressure of

Dense bulk Fe3C samples were synthesized by the high pressure–temperature method using a large-volume cubic press. The Hugoniot data of the Fe3C samples were measured from 65 to 250 GPa on a two-stage light gas gun. The shock velocities were measured by the electrical pin technique, and the particle velocities were calculated by the impedance match method. The shock velocity (Us) and particle velocity

At mid-ocean ridges, oceanic crust is emplaced in a narrow neovolcanic region on the seafloor, whereas basaltic melt that forms this oceanic crust is generated in a wide region beneath as suggested by a few geophysical surveys. The combined observations suggest that melt generated in a wide region at depths has to be transported horizontally to a small region at the surface. We present results from

We examined SKS-SKKS splitting intensity discrepancies for phases that sample the lowermost mantle beneath North America, which has previously been shown to exhibit seismic anisotropy using other analysis techniques. We examined data from 25 long-running seismic stations, along with 244 stations of the temporary USArray Transportable Array, located in the eastern, southeastern and western U.S. We identified

The composition of Archean volcanic crust can be characterized by a higher Mg/Si ratio than modern mid-ocean ridge basalt (MORB), because of the higher degree melting from the warmer mantle in the Archean. Although modern MORB may become less dense than the surrounding mantle beneath the mantle transition zone (MTZ), the Mg-rich composition of Archean volcanic crust may result in the different density

We processed the data recorded by 32 continuous GPS stations from the Crustal Movement Observation Network of China and combined them with published GPS observations in a common geodetic reference frame to better depict the ongoing crustal velocities and deformation field of Northeast Tibet. The derived velocity field indicates that the deformation of Northeast Tibet is characterized mainly by crustal

The frequency-dependent attenuation characteristics of P-waves (Qα), S-waves (Qβ) and coda waves (Qc) in north-west (NW) Himalaya and its surrounding region have been estimated using 515 micro to moderate earthquakes (2.5 ≤ Mw ≤ 5.0) recorded from January 2008 to November 2015 for a central frequency range (fc) varying from 1.5 to 12 Hz. Average attenuation relationships of Qc, Qα and Qβ found as:

The Florina basin (NW Greece) embodies sources of natural CO2 emissions, which are aligned parallel to the NE-SW striking regional major normal faults. The study area is characterized by low to moderate seismicity, as historical information and instrumental data reveal. During February 2013 to January 2014 an outburst of seismic activity emerged, consisting of more than 2000 located earthquakes, with

In this article, we propose a new inversion scheme to calculate the melt volume fractions from observed seismic anomalies in a low-velocity layer (LVL) located atop the mantle transition zone. Our method identifies the trade-offs in the seismic signature caused by temperature, solid composition, melt volume fraction, and dihedral angle at the solid-melt interface. Using the information derived from

We analyze a two-phase porous medium whose permeability and solid viscosity are dependent on porosity. It has been established experimentally and numerically that when such a medium is subjected to shear, the porosity rearranges into stripes of high and low porosity known as melt bands (Holtzman et al., 2003; Katz et al., 2006; Butler, 2009). This study uses linear theory and numerical simulations

Edge-driven convection, which affects partial melting, intraplate volcanism, and dynamic topography, is small-scale convection that occurs along a lithospheric keel with a sharp contrast in lithospheric thickness. Various factors, including Rayleigh number, lateral mantle temperature heterogeneity, and geometry of the keel, influence the edge-driven convection, and the correlation between edge-driven

The Andaman–Sumatra–Java subduction zone is characterized by significant spatial variations in subducting plate age, subduction velocity, and slab bending. With (i) the uplifting controlled by the Ninety East Ridge in the north, (ii) trench eroding affected by the Roo Rise in the south, and (iii) the highly deformed Warton Basin in front of the trench cut through by a series of strike-slip faults,

In this study, we propose an analysis of the earthquake clusters that occurred in North-Eastern Italy and western Slovenia from 1977 to today. Given a mainshock generating alarm in the population, we are interested in forecasting if a similar magnitude earthquake will follow. We classify the earthquake clusters associated with mainshocks of magnitude Mm into two classes: if the strongest aftershock

Recently, an earthquake sequence formed by a series of subsequences characterized by large earthquakes (three events M ≥ 6.0 and five events M ≥ 5.0) occurred in the Central Apennines in 6–7 months during 2016–2017. Several studies interpreted this cascading type of earthquake occurrence as associated with fluid movements through an interconnected network of cracks around the active faults that triggered

As the major component of garnet, the second most abundant phase in Earth's transition zone, MgSiO3-majorite plays a fundamental role in controlling the state and dynamics of Earth's mantle. However, due to challenges of experiments and simulations, there are still very limited data on the elastic properties of MgSiO3-majorite at simultaneously high temperatures and pressures. In this study, we have

The XiLuoDu reservoir dam located on the Jinsha River is one of the largest dams in the world. Nearby faults are very active, and two M > 7 strong earthquakes have occurred around the dam. Simulating the rupture dynamics of potential earthquakes on the surrounding faults is very important to estimate the seismic hazard for the dam. In this research, we use the curved grid finite difference method (CG-FDM)

As a typical rifted margin, the coastal region of the northern South China Sea has experienced many large crustal earthquakes in the past 400 years. For example, two destructive earthquakes with ~M7.0 in 1600 and ~M7.5 in 1918 occurred close to the NanAo Island. However, the mechanism of these earthquakes and seismotectonics of the region are still unclear. In this work we make the first study of the

We successively adopt H-k stacking of receiver functions (RFs) and joint inversion of RF and surface wave dispersion with Gaussian factors of 1.0, 2.0 and 3.0 to invert the crustal thickness (H), average Vp/Vs ratio (k) and S-wave velocity beneath 146 broadband seismic stations in the middle-southern segments of the Tanlu Fault Zone (TLFZ) and adjacent regions. These observations, together with previous

Magnetic fabric and rock-magnetism studies were performed on 153 dikes from diabase, lamprophyre and alkaline dike swarms that outcrop on the island of Ilhabela, NE São Paulo State. The dikes crosscut Archean and Proterozoic polymetamorphic rocks. Their thicknesses range from a few centimeters to 4 or 5 m. They trend predominantly N30-60E with a very steep (~60°) to vertical dip. Magnetic fabrics were

The role of heat flow coming from the core is often overlooked or underestimated in simple models of Earth's thermal evolution. Throughout most of Earth's history, the mantle must have been extracting from the core at least the amount of heat that is required to operate the geodynamo. In view of recent laboratory measurements and theoretical calculations indicating a higher thermal conductivity of

Besides iron, the Earth's core also contains 5–10% of nickel and several light elements such as H, C, N, O, Si and S. Fe-Ni alloys have been considered as the host material with 10% Ni. The impurity atoms which are comprised of the light elements have been incorporated at different concentrations in the host alloy, giving rise to ternary alloys. All these systems have been subjected to compression

In this study, we analysed 2708 receiver functions (RFs) using data recorded by 53 seismographic stations that surround Mt. Merapi and Mt. Merbabu – two volcanos in Central Java - to map the boundary between Earth's crust and upper mantle. We observe that a number of RFs from this new dataset have complex signals and do not exhibit typical RF characteristics; in particular, where the converted Ps signal

The effective elastic thickness (Te) of the lithosphere reflects the long-term flexural strength and provides mechanical information about the evolution and deformation of the lithosphere. The Chinese mainland and its surroundings (CMS) comprise sharply contrasting tectonic domains and involve a complex evolution history. In this paper, we apply a joint inversion of real admittance and coherence calculated

The Upper Yangtze Craton (UYC) has stayed in a long-term stabilization state. Its thermal history can be portioned into two parts: secular evolutionary trend and short-lived thermal perturbations. The former is simulated by a two-dimensional forward transient thermal model, and the latter is discussed by reviewing previous studies. The numerical modeling indicates the UYC tended to be cooling as it

For the commonly-used laboratory frictional earthquake model, unstable slip usually occurs without any end constraint. This experimental design is contradictory to a simple fact: real faults are confined by their surroundings, and the relative sliding is not end-free. To investigate the effects of end constraint conditions on the stick-slip behaviors, direct shear tests are conducted on PMMA sheets

The Indian plate began to subduct under the Eurasian plate in the late Mesozoic. Since the Eocene, continuous continental collision has resulted in the uplift of the Tibetan Plateau with extensive volcanic activity. Geophysical and geochemical studies have suggested that the Indian plate was subducted and that volcanism originated in the deep upper mantle. However, the depth range of the subduction

Variations of the recent seismicity in and around the Central Anatolian region of Turkey were evaluated based on the seismic b-value, standard normal deviate Z-value, GENAS modelling, annual probabilities and return periods of the earthquakes. The catalog includes 16,702 earthquakes between 1974 and 2019 with magnitudes from 1.0 to 6.3. Time distribution of b-value shows that there is a tendency to

The Earth's Inner Core may rotate at a different speed than Earth's crust–mantle. We use observations for antipodal earthquake and station pairs to examine the arrival time shift of the whispering-gallery wave which propagates tangentially along the top of the Inner Core. Observations of these waves for earthquakes which occurred at the same location reveal that travel times vary by ≥0.2 s over the

Quartz, one of most abundant mineral in the continental Crust, is conventionally used in exploration of the stress state of the Crust through analysis of its structural and mechanical properties. To better infer the state of stress in the Crust, we quantified such properties of quartz under non-hydrostatic stress environment through First-principles calculation. The reduction of the crystal lattice

Wave propagation in rocks induces fluid pressure gradients and flow between stiff intergranular pores and compliant microfractures. This, in turn, leads to wave anelasticity, i.e., attenuation and velocity dispersion. Three known squirt-flow models attempt to explain this phenomenon. Based on these theories, we reformulate a new one, where we derive the dry-rock moduli on the assumption that the boundary

In present study the model is proposed to describe the dynamics of the rock fracture process. Rock formation is assumed in the form of a nested self-similar hierarchical structure. The hierarchical structure scheme is chosen in accordance with the experimentally verified criterion of fracture. The failure probability of each structure level is calculated as a function of time, temperature, material

In this study we investigate detailed Moho variations beneath Northeast China by applying the arithmetic mean, back-projected and Fresnel-zone migration imaging methods to a total of 169,602 high-quality P-wave receiver functions from seismograms of 2903 teleseismic events recorded at 127 NECESSArray stations and 321 China Earthquake Administration stations. Our results show that the Moho depth variations

Core freezing and resultant compositional convection are likely important drivers for dynamo activity in large terrestrial bodies like the Earth. The solidification of compositional mixtures, such as iron and sulfur, generates mush zones of partial melt at the freezing front, which can eject chemically buoyant or heavy liquid that then drives convection. For smaller bodies such as planetesimals in

We use shear-wave splitting (SWS) above small earthquakes to monitor stress-variations before the 2014 Bárðarbunga seismic crisis and dyke intrusion in central Iceland. SWS is sensitive to stress-induced variations in the internal geometry of the distributions of stress-aligned fluid-saturated microcracks pervading almost all crustal rocks. This allows stress-accumulation before both impending earthquakes

In this study, the crust and upper mantle density distribution across the Iranian plateau along a ~1500 km profile are investigated using an integrated modeling of potential field data (gravity, geoid and topography) and by assuming local isostatic equilibrium. Our profile is initiated in Arabian platform and running through the main geological structures of Iran including Zagros orogen, Sanandaj –

The continental collision between the Arabian and Eurasian plates plays an important role in the geodynamical evolution of the Zagros and Iranian plateau. In order to investigate the upper mantle structure across the collision zone, we calculated the absolute and relative shear-wave velocity structure along a dense and long temporary seismic profile in NW Iran. The probabilistic 1-D absolute shear-wave

Historical documents, archives and old photographic collections allowed to analyze 877 direct geomagnetic measurement data obtained by sailors (including pirates), United State Coast and Geodetic Survey and National Astronomical Observatory since 1587. The updated catalogue includes 844 values of magnetic declination, 495 of inclination, 467 of the horizontal intensity component (H) and 455 of the

Preserved deformed depositional sequences along passive continental margins are important repositories of natural resources as well as key laboratories for understanding rift-drift tectonics. With better post signal processing schemes, interpretation techniques, and potential data, imaging sedimentary basins along these margins has reached unique levels of refinement. This, in turn, has led to considerable