We simulate the strong ground motion for an expected major earthquake (Mw 7.0) beneath the Bhutan Himalayan region with an empirical Green's function method using waveforms recorded from the 2009 Bhutan mainshock (Mw 6.1) and its largest aftershock (Mw 5.1). Fault orientation and location of the simulated event extend the length of the fault plane determined from the 2009 Bhutan mainshock and aftershock

We address the uncertainty related to cross-correlation waveform time shift measurements, particularly related to temporal changes in inner core seismic waves. Details of the cross-correlation measurement, including data processing, window length, pick time, sampling rate and the algorithm itself, all affect the calculated time shift. By systematically varying measurement parameters for a set of earthquake

Over the last decade, seismological studies have shed new light on the properties of the mantle lithosphere and their physical and chemical origins. This paper synthesizes recent work to draw comparisons between oceanic and continental lithosphere, with a particular focus on isotropic velocity structure and its implications for mantle temperature and partial melt. In the oceans, many observations of

Variations of the geomagnetic field during the past millennia can be obtained by investigating archeological material. The spatial distribution of the available data across Europe is rather uneven and only about 15% of the sites provide a full vector record of the geomagnetic field. Here we report 39 new reliable paleointensity data for sites from Austria, Germany and Switzerland, with ages ranging

This work illustrates the performance of a focused algorithm for 2D inversion of potential field geophysics (gravity and magnetic) in regions with rugged topography. A non-structured model discretization mesh is performed through Delaunay triangular cells to accurately represent the rugged observation surface and recover complex-shaped sources. Several synthetic single and multi-source targets are

We present a model of pressure-dependent melting temperature to describe the physical fact that both cooling and pressurization can cause the solidification of liquid metal. Based on the Force-Heat Equivalence Energy Density Principle, an equivalent relationship between the heat energy variations during cooling and the mechanical work during pressurization is established as the molten metal solidifies

Archaeomagnetism is a research area that reconstructs ancient geomagnetic fields mainly using baked samples (especially baked artifacts) containing magnetic minerals such as magnetite and hematite. Archaeomagnetism can be applied to reveal temporal changes in the geomagnetic field related to deep-earth dynamics, and to estimate the age of archaeological remains and artifacts. Reconstruction methods

The study used total magnetic intensity (TMI) data to evaluate the incidence and characteristics of the Balapur fault in the Kashmir basin, NW Himalaya. The ground magnetic surveys were carried out at ~25 m station spacing in various linear profiles and grids across the fault. The magnetic measurements external to the Earth were recorded after every minute to remove the diurnal variations. The convenient

Most analytical solutions of deformation near active and volcanic centers are limited to simple geometries and homogeneous media. To solve more complex problems, we have developed a FEM software package called Def3D for modeling deformation caused by earthquakes or magma chambers in laterally inhomogeneous media. Features presently available include modeling of split node technique, equivalent body

The InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) mission began collecting high quality seismic data on Mars in February 2019. This manuscript documents the seismicity observed by SEIS, InSight’s seismometer, from this time until the end of March 2020. Within the InSight project, the Marsquake Service (MQS) is responsible for prompt review of all seismic

More than 2769 seismogram of 633 earthquakes recorded by 18 stations of the Iranian Seismological Center (IRSC) during 2006–2016, was selected to estimate spectral attenuation relation in the Central and eastern Iran. For each rotated combine horizontal record, a shear-wave window was selected, and a 5% taper was applied at each end of the window. In frequency domain by using a local regression smoothing

Mantle-crust interaction occurring in various ways has been proposed for a long time, but the details of its mechanism at the crust-mantle transition zone and the lower crust are poorly known. This study reports a layered pyroxenite-granulite xenolith from the Cenozoic basalts of Hannouba in the North China Craton. Petrological and mineral chemical investigations reveal that the pyroxenite layers are

It has been proposed that magnetic flux expulsion due to outer core fluid upwellings may affect the geomagnetic secular variation on the core-mantle boundary (Bloxham, 1986). In this process intense horizontal field lines are concentrated below the outer boundary, introducing small radial length scales and consequently strong radial diffusion. Here we explore such magnetic boundary layers in numerical

High resolution aeromagnetic and Shuttle Radar Topography Mission data from parts of the N-S axis of the western half of Nigeria that covers the Middle Niger and Sokoto Basins provide a coherent picture for the surface expression of the linear and curvilinear features and the topography of the zone. It equally identifies the boundaries of the sedimentary basins with depths up to 950 m, thereby establishing

The variation of the Earth's magnetic field over the last millennia is poorly known in Africa, especially in Sub-Saharan Africa that represents less than 1% of the global archeomagnetic dataset. Fourteen iron furnaces from Kenya and Chad have been studied here for archeomagnetic purposes. These structures were dated by 14C from the 14th century in Kenya and from the 18-19th centuries in Chad. Samples

Nearly 40 years ago, Emile Thellier published an article summarizing the archeomagnetic data he had obtained during his career, which had allowed him to recover the main features of the directional variations of the geomagnetic field in France for the last two millennia. This database went on to be significantly completed 25 years ago by Ileana Bucur, who had taken over Thellier's work on archeomagnetism;

The InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) mission landed on the surface of Mars on November 26, 2018. One of the scientific instruments in the payload that is essential to the mission is the SEIS package (Seismic Experiment for Interior Structure) which includes a very broadband and a short period seismometer. More than one year since the landing, SEIS

This study presents new high precision age and full-vector archaeomagnetic data from a kiln excavated in the Roman archaeological site of Mitreo's house (Mérida, Badajoz, Spain). The age of the kiln was obtained by the stratigraphic method and by the ceramological study of the italic and sigillata pottery found with a very precise age date of 55 ± 15 years AD. Rock-magnetic experiments pointed towards

In this study continuous waveforms are observed at a short-period dense seismic array which consisted of 302 stations in the Weifang segment of the Tanlu fault zone from August to October 2017. A total of 122,302 Rayleigh wave phase velocity dispersion curves at 1.0–7.5 s periods are extracted to infer a high-resolution shear-wave tomography model of the shallow crust under the region. Our model well

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

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

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

Stick-slip failure, as a possible mechanism for destructive shallow focus earthquakes, often occurs in heterogeneous faults. To investigate the physical processes of stick-slip failure in heterogeneous faults, direct shear tests are performed in the laboratory, combined with the use of multi-channel high-speed dynamic strain acquisition system, on the bimaterial samples. The bimaterial samples consist

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

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

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

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

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 collected in the oceanic realm have substantially increased. These additional constraints have helped to elucidate many aspects of

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