As a comment on Seismic Electric Signals (SES) and earthquakes: A review of an updated VAN method and competing hypotheses for SES generation and earthquake triggering, herein we present the analysis of time series gathered by three MT stations located in the Eastern Cordillera of Colombia, for evaluating the electric and magnetic fields during an interval of several days. Records allow estimating

We report experimental results on the bulk modulus of partially molten peridotite at mantle conditions, using a multi-anvil high pressure apparatus coupled with synchrotron X-ray radiation. A sinusoidal pressure at an amplitude of 180 MPa with period of 360 s is applied to the sample as a function of temperature. The sample volume derived from the X-ray radiograph also demonstrated sinusoidal variation

Remanent magnetization and active magnetic fields have been detected for several telluric planetary bodies in the solar system (Earth, Mercury, Moon, Mars) suggesting the presence of core dynamos active at the early stages of the planet formation and variable lifetimes. Among the factors controlling the possibility of core dynamos generation, the dynamics of the surrounding silicate mantle and its

Seismic anisotropy is a key observational tool for mapping flow in Earth's upper mantle. However, interpreting patterns of anisotropy relies on a firm understanding of the microphysical mechanisms that generate anisotropy. Here we discuss our current understanding of the generation of intrinsic and extrinsic seismic anisotropy in upper-mantle rocks. Intrinsic anisotropy results from the elastic anisotropy

The Santorini-Amorgos zone is located in the central part of the Hellenic volcanic arc and is hosting eight large faults as well as Kolumbo and Santorini volcanic centers. The largest earthquake (Mw ~ 7.1) in the southern Aegean during the 20th century also occurred in this area on 9 July 1956. A total of 1868 crustal events were recorded by temporary networks during September 2002 to July 2004 and

The moment tensor inversion is a commonly-used method to interpret source mechanisms of microseismicity. In the inversion for real data (e.g. microseismicity recorded during hydraulic fracturing), the waveforms recorded by sensors can be the mixtures of signals and noise, or the superposition of signals generated by multiple sources. Then the traditional approach may result in inaccurate solutions

Volcanoes are complex systems that evolve in space and time as a result of their eruptive activity. Volcanic eruptions represent the ultimate expression of a complex interplay between internal and external processes that span across different time scales. Deciphering how internal and external processes interact at the time scale of eruptions may provide key insights on the temporal evolution of eruptions

Inference of thermodynamic state and full-spectrum mechanical behavior of the lithosphere and asthenosphere is a central problem in geophysics, implicating our understanding of the convection patterns, transient responses and chemical composition of the planet. Anelasticity is responsible for significant relaxation of stress associated with seismic wave propagation in the asthenosphere, while irreversible

The 2016 Pedernales earthquake (Mw 7.8), is part of the sequence of large earthquakes in Ecuador and Colombia: 1906 (~8.8 Mw), 1942 (Mw 7.8), 1958 (Mw 7.7), 1979 (Mw 8.2), all these events with a focal mechanism of the thrust fault type. In this research, we have obtained the seismic source distribution (indicating the presence of 2 main asperities), from inversion of teleseismic signals, as well as

Well-exposed lava sequences with available geochronological information may provide invaluable information on the fine characteristics of the Earth's magnetic field variation. A paleomagnetic study has been performed on twenty Pleistocene age, sub-horizontal lava flows in the Javakheti Highland (Lesser Caucasus). The sequence is formed by calc-alkaline basaltic lavas and is divided by a thin sedimentary

This study attempts to characterize the nature of seismicity, anisotropy and coherency of deformation in the crust and upper mantle beneath the Doda- Kisthwar region (DKR), Jammu, located in the Kashmir seismic gap of NW Himalaya. Location of earthquakes using local waveforms, and shear wave splitting in local and teleseismic waveforms recorded at 5 temporary stations, are performed for this purpose

Decompression melting of the upper mantle produces magmas and volcanism at the Earth's surface. Experimental petrology demonstrates that the presence of CO2 and H2O enhances peridotite melting anywhere within the upper mantle down to approximately 200–300 km depth. The presence of mantle melts with compositions ranging from carbonate-rich to silicate-rich unavoidably affects the geophysical signals

Since the mid-19th century, direct measurements of both intensity and directions of the Earth's magnetic field have been available, allowing an accurate determination of its spatio-temporal variations. Prior to this time, between ∼1600 and 1840, only direct directional measurements are available. Therefore, the construction of global field models over this period requires either a specific treatment

High pressure shock metamorphism in ordinary chondrites involves heating and melting of individual phases from shock entropy, pore collapse, frictional heating, and heat transfer. Numerical models using shock physics codes have recently been used to comprehend the mechanism of shock heating and melting in multiphase mesoscale models. Such models suggest that the formation of sulfide and metal melt

Crustal thickness and its variation can provide important insights into the tectonics of a region. The most popular methodology to determine crustal thickness – receiver function analysis utilizes converted phases from the Moho discontinuity. Although the reflection co-efficient is comparable to the transmission co-efficient, reflected phases are rarely used for determining crustal thickness. We tested

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

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 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

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