Through a probabilistic approach, this study provides estimates of the time-averaged shear-wave velocity in the top 30 m of soil column (Vs30) for the stations of Iranian strong-motion network. For this purpose, we consider the strong-motion dataset of the Road, Housing and Urban Development Research Center for the period 1975–2018 from which 3828 three-component records from 1636 events with moment

Eastern margin of the Qinghai-Tibet plateau and western margin of the Yangtze craton has a complex crust-mantle structure and is an important region for studying the crust-mantle deformation mechanism. Because the Rayleigh surface wave group velocity has a strong constraint on the structure of the crust and upper mantle, a lot of researches have used the Rayleigh surface wave group velocity to invert

Electrical property of the Earth should be best depicted by anisotropic 3D models, while many numerical issues remain to be solved before it becomes practical, such as implementation complexity and computational efficiency. Magnetotellurics (MT) is the primary method to explore electrical property of the deep Earth, and MT forward modeling with 3D anisotropy has been investigated primarily by finite

Low-velocity layer (LVL) within the continental crust is usually closely associated with tectonic events, thus it may reflect ongoing processes or offer a chance to backtrack the evolutional history. Mid-crustal LVL has been reported in the northern coast of the South China Sea (SCS) by several geophysical studies, but the 3D distribution of LVL in the whole coastal area is still poorly known. Here

We compare viscoelastic models to obtain the seismic properties of a partially molten rock as a function of temperature, pressure and tectonic stress. Invoking the correspondence principle, the material of the inclusions is represented by a Maxwell mechanical model, where the Arrhenius equation and the octahedral stress criterion define the Maxwell viscosity. One of the most advanced models is the

A deep crustal strike-slip earthquake swarm that occurred in the intracontinental region of the southwestern Korean Peninsula is investigated. The earthquakes are detected using matched filter analysis. The hypocenters are then refined, showing more than 500 micro to small strike-slip earthquakes concentrated on a fault plane with dimensions of 500 m by 300 m at a depth of ~21 km. The low temperature

This study summarizes the pattern of directional paleomagnetic secular variation (PSV) in five previously-published Holocene records from East Asia. Each record is high in resolution and well-dated. We have developed equi-spaced (100-year increment) time series for the declinations and inclinations for the five sites and compared their overall directional variability. We see evidence of nine correlatable

Understanding metal-silicate differentiation in small rocky bodies that accreted early in solar system history requires quantification of the effects of variable amounts of silicate melt and molten metal on the connectivity of metal-rich liquids. To shed light on this question, the equilibrium geometry and textural ripening of metal grains in the vicinity of the metal interconnection threshold have

Central Inner Mongolia is one of the areas with intense volcanic activity in the Cenozoic. In order to better understand the origin of these volcanoes, a study of magnetotelluric sounding (MT) was carried out. This study aims to learn about the mechanism of deep volcanic areas from the electrical point of view. Broadband and long-period MT data were collected on a 500-kilometer section at central Inner

The Qeshm earthquake with magnitude Mw 6.0 occurred on November 27, 2005, on a southern island in Iran and was followed by many aftershocks. We analyzed the aftershock waveforms and the first arrival traveltimes to calculate the 3D velocity model. The tomographic procedure was conducted in three different depth ranges from the subsurface to a depth of 17 km beneath Qeshm Island. The subsurface was

The thermochemical evolution of oceanic lithosphere and its interaction with the underlying asthenosphere exerts a fundamental control on the dynamics of the Earth system. Since the 1960s, the range, accuracy and spatial coverage of geophysical and geochemical datasets have increased substantially. These additional constraints have helped to elucidate aspects of the lithosphere-asthenosphere system

Constraining Earth's bulk composition is fundamental to understanding our planet's formation and evolution. While the lower mantle accounts for a majority of the bulk silicate Earth, it is also the least accessible. As experimental and theoretical mineral physics constraints on mineral elasticity at lower mantle temperatures and pressures have improved, comparisons between predicted seismic velocity

An equation of state can be converted into a full constitutive equation by adding to the strain energy a deviatoric component as a function of density change, which specifies incremental shear properties under compression. A suitable functional form for the shear term can be found from a semi-empirical linear relation between shear modulus, bulk modulus and pressure satisfied by experimental and computational

We show slab-parallel advection and Rayleigh-Taylor instability (RTI) as two competing gravity-driven flow mechanisms in the melt-rich layer atop a subducting slab. Scaled laboratory model results, supported by CFD simulations, indicate a transition of the RTI to advection mechanism at a threshold slab-dip angle (α) between 20° and 30°. The advection mechanism results in updip flow, forming a single

It is shown, that continuous changes of angular velocity of rotation of the plastically-elastic Earth should cause the continuous coupled deformation of a crustal layer, redistribution of masses in a sub-crustal layer and the change of density associated with it, and also, as consequence of these phenomena, a polar pulsation of a figure when polar diameter of the Earth increases and decreases with

Modeling and analysis of gravity and earthquake data of a critically dynamic northeastern region of India assumes a special significance for understanding the seismicity and geodynamics. In this paper, the relation between lateral heterogeneity of gravity interfaces with subsurface structures, and seismic characteristics of northeast India are studied in detail to understand the seismicity and dynamics

The occurrence of ε-Fe2O3 in archaeological samples that have been subjected to high temperatures is gradually being detected by the use of micrometric structural characterization techniques. This work provides new information by revealing that the ε-Fe2O3 is formed as a response to temperature, the aggregation state and the position within the baked clay with respect to the nearest heat source. In

It is of great importance to study active tectonics in Guangxi, China which is a region with relatively high level of seismic hazard. In this work, we attempt to apply the Load/Unload Response Ratio (LURR) method to test stress state of tectonic field in Guangxi and find obvious difference in the periods before and after earthquakes on the Longmenshan (LMS) fault zone. The regions with higher stress

Between February 6 and 12, 2016, an earthquake sequence affected the western sector of the Hyblean foreland domain in SE Sicily (Italy), a region characterized by several disastrous events, as the seismic history describes, of which little is still known about the seismogenic sources. Despite the low magnitude of most events (MLmax 4.3), the sequence represents one of the largest episodes of seismic

Among the mechanisms of the mass transport within the Earth's crust and the upper mantle the magma movement within the dykes is very important. In some dykes, the magma movement is represented by almost free flow infilling more or less open fractures in the host rocks, while it has character of forceful injection of the host rocks in the other dykes. The magnetic fabric originated by the free flow

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

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

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

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

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 was 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 of the western Pacific

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

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

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