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The transverse coherence functions (TCFs) of phase and amplitude fluctuations of a seismic wave are powerful to estimate the spatial distribution, length scales, and strength of random heterogeneities. However, TCFs have been formulated for transmitted waves only, not for reflected waves. In this paper, we derive reflection TCFs for Gaussian random media using the mirror reflection principle. Furthermore

Due to a sharp contrast in elastic properties across the basement rocks of sedimentary basins (SBs), strong reverberations are generated during the passage of seismic waves. Traditional receiver function methods become inadequate for imaging crustal structure due to the existence of these strong reverberations. We investigate the feasibility of an autocorrelation technique to extract vertical component

The long‐wavelength negative gravity anomaly over Hudson Bay coincides with the area depressed by the Laurentide Ice Sheet during the Last Glacial Maximum, suggesting that it is, at least partly, caused by glacial isostatic adjustment (GIA). Additional contributions to the static gravity field stem from surface dynamic topography, core‐mantle boundary (CMB) topography, and density anomalies in the

Si and C are cosmochemically abundant elements soluble in hcp Fe under pressure and temperature and could therefore be present in the Earth's inner core. While recent ab initio calculations suggest that the observed inner core density and velocities could be matched by an Fe‐C‐Si alloy, the combined effect of these two elements has only recently started to be investigated experimentally. We therefore

The style of subduction that prevailed on the early Earth, or even whether subduction was prevalent at all, is an important question in the evolution of Earth's crust, mantle, and surface environment. Here, two‐dimensional numerical convection models, that include grain size evolution to generate weak plate boundaries, reveal a clear transition in subduction behavior with increasing internal heating

Seismic wavespeed is controlled by a number of factors, including temperature and chemical composition, as well as the presence of volatiles and partial melt. Tomography provides a powerful constraint on wavespeed variations, but if only VP or VS variations are imaged it is challenging to separate the competing effects of these factors and make a full interpretation of seismic anomalies. In this study

Deformation experiments were conducted to investigate the influence of apparatus stiffness on frictional stability during dehydration of antigorite. These experiments also provided a novel way to constrain relationships between fault slip rate and reaction weakening. Experiments were conducted at a confining pressure of 1 GPa using a Griggs apparatus with a modified loading column. During experiments

Nearly every type of slip behavior of which megathrusts are known to be capable of has been observed within a narrow ~75‐km‐wide strip of the Sunda megathrust—the Banyak Islands subsegment. The diverse list of recorded slip events starts with the great 1861 MW ~ 8.5 earthquake and includes the 1907 MW ~ 8.2 shallow tsunami earthquake, the 1966–1981 slow slip event, the great 2005 MW 8.6 Nias‐Simeulue

We present a novel geodynamic approach that can potentially tighten existing constraints on mantle rheology. This new approach, which we call probabilistic geodynamic modeling, is applied here to the rheology of the upper mantle. We combine the numerical modeling of plate‐driven corner flow and the seismic observation of radial anisotropy, aiming to reduce substantial uncertainties associated with

The Leech River fault (LRF) zone located on southern Vancouver Island is a major regional seismic source. We investigate potential interactions between earthquake ruptures on the LRF and the neighboring Southern Whidbey Island fault (SWIF), which can be interpreted as a step‐over fault system. Using a linear slip‐weakening frictional law, we perform 3‐D finite‐element simulations to study rupture jumping

Subduction style is controlled by a variety of physical parameters. Here we investigate the effect of subducting plate length on subduction style using laboratory experiments of time‐evolving buoyancy‐driven subduction in 3‐D space. The investigation includes two experimental sets, one with a lower (~740) and one with a higher (~1,680) subducting plate‐to‐mantle viscosity ratio (ηSP/ηM). Each set involves

The Mw 6.5 Norcia earthquake occurred on 30 October 2016, along the Mt Vettore fault (Central Apennines, Italy), it was the largest earthquake of the 2016–2017 seismic sequence that started 2 months earlier with the Mw 6.0 Amatrice earthquake (24 August). To detect potential slow slip during the sequence, we produced Interferometric Synthetic Aperture Radar (InSAR) time series using 12‐ to 6‐day repeat

This study presents an improved approach to common‐conversion point stacking of converted body waves that incorporates scattering kernels, accurate and efficient measurement of stack uncertainties, and an alternative method for estimating free surface seismic velocities. To better separate waveforms into the P and SV components to calculate receiver functions, we developed an alternative method to

Seismic scattering and attenuation at volcanoes, thought to be strongest on the Earth, can be used to map volcanic feeding systems. We systematically analyzed high‐frequency (5–10 Hz) seismograms of volcano‐tectonic earthquakes at Galeras volcano (Colombia) and active sources at Kirishima, Unzen, Bandai, and Iwate volcanoes (Japan) to investigate their scattering and attenuation characteristics. The

Inverse magnetic fabrics defined by anisotropy of magnetic susceptibility with the longest principal axis perpendicular to bedding were identified in the studied samples of Ordovician sedimentary rocks from the Barrandian area, Czech Republic. These fabrics are related to ankerite fibers in association with cone‐in‐cone structures. To understand the meaning of such inverse magnetic fabrics for geological

The variation of the seismic properties with frequency of a brine‐saturated sandstone sample with a porosity of 22% was measured using a forced oscillation apparatus. Two pairs of orthogonal biaxial strain gauges were pasted at different locations at the length‐center of the sample. In the frequency range of 1‐300 Hz, using these two pairs of strain gauges, we observed experimentally the same global

Understanding and predicting fracture propagation and subsequent fluid flow characteristics is critical to geoenergy technologies that engineer and/or utilise favourable geological conditions to store or extract fluids from the subsurface. Fracture permeability decreases non‐linearly with increasing normal stress, but the relationship between shear displacement and fracture permeability is less well

Natural gas hydrate is considered to be a promising future energy resource; therefore, obtaining its physical properties is crucial for evaluating gas production efficiency and developing reasonable exploitation strategies. In this study, we present a novel pore‐scale 3D morphological modeling algorithm considering various saturation and occurrences (cementing and pore‐filling) of hydrate in sediments

We modify the Modified Cam‐Clay (MCC) model for large stress ranges encountered in geological applications. The MCC model assumes that the friction angle (ϕ) and the slope of the compression curve (λ) of a mudrock are constant and thus predicts constant values for the lateral effective stress ratio under uniaxial, vertical strain (K0) and undrained strength ratio ( ). However, experimental work shows

Numerous large‐scale geophysical flows propagate with low apparent basal friction coefficients but the source of such phenomenology is poorly known. Motivated by scarce basal friction data from natural flows, we use numerical methods to investigate the interaction of granular flows with their substrate under idealized conditions. Here we investigate 3D monodisperse and polydisperse fluid‐particle granular

As the largest and best‐exposed example of paleo fast‐spreading oceanic crust on land, the Samail Ophiolite in the Sultanate of Oman represents an ideal natural laboratory for investigating deep crustal processes at fast‐spreading mid‐ocean ridges. We studied two layered gabbro sequences from different stratigraphic depths: one from the middle of the plutonic crust showing dm‐scale modal layering (i

Geysers are rare geologic structures that intermittently discharge liquid water and steam driven by heating and decompression boiling. The cause of variability in eruptive styles and the associated seismic signals are not well understood. Data collected from 5 broadband seismometers at Lone Star Geyser, Yellowstone National Park are used to determine the properties, location and temporal patterns of

Fragile geologic features (FGF) are used as negative indicators of strong ground motion. By evaluating the stability of FGFs and determining their age, it is possible to constrain the local maximum seismic ground acceleration that has occurred during their lifetime. This methodology was originally developed to analyze precariously balanced rocks (a subset of FGFs), and has been used to assess long‐term

To test the ability of Mg and Zn isotopes in discriminating between different types of mantle metasomatism and identifying deep carbon cycling, here we present a comparative study on two types of Cenozoic lavas in SE Tibet, that is, K‐rich (potassic‐ultrapotassic) lavas and Na‐rich alkali basalts. The contrasting bulk rock chemical compositions, Sr‐Nd isotopic ratios, and olivine chemistry between

The magnetic anisotropy carried by strongly magnetic particles such as magnetite or ferrofluid‐filled pores is generally composed of shape anisotropy and distribution anisotropy. Their relative importance in rocks depends on numerous factors and has been discussed controversially. A major challenge in estimating their contributions so far has been that models for distribution anisotropy only exist

The Daguangbao landslide was the largest landslide triggered by the "5.12" Wenchuan Mw 7.9 earthquake. This landslide is among the few superlarge‐scale landslides of 1 billion m3 magnitude worldwide. As the landslide accumulation represents a potential hazard, long‐term monitoring and geological interpretation of the Daguangbao landslide is important to reveal the post‐sliding deformation characteristics

In western Canada, there has been an increase in seismic activity linked to anthropogenic energy‐related operations including conventional hydrocarbon production, wastewater fluid injection, and, more recently, hydraulic fracturing (HF). Statistical modeling and characterization of the space, time, and magnitude distributions of the seismicity clusters is vital for a better understanding of induced

Large amounts of methane, a potent greenhouse gas, are stored in hydrates beneath the seafloor. Sea level changes can trigger massive methane release into the ocean. It is not clear, however, whether surficial seafloor processes can cause comparable discharge. Previously, fluid migration was difficult to study due to a lack of spatially dense seismic and thermal observations. Here we examine a gas

Predicting the instabilities that occur during the chemical reaction between a percolating fluid and a soluble rock leading to the development of macroscopic channels called wormholes is a key for understanding many geological processes. Their shape and their spatial distribution depend on two dimensionless numbers, namely Damköhler (Da) and Péclet (Pe) numbers. Although the dissolution phenomenon

Gravitationally consistent solutions of the Sea Level Equation from leakage‐corrected monthly‐mean GFZ RL06 Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow‐On (GRACE‐FO) Stokes coefficients reveal that barystatic sea level averaged over the whole global ocean was rising by 1.72 mm a−1 during the period April 2002 until August 2016. This rate refers to a truely global ocean averaging

We image the thermo‐chemical structure of crust and mantle underneath the North American continent by inverting recordings of P‐to‐s (Ps) and S‐to‐p (Sp) converted seismic body waves (receiver functions; RF). Through careful data selection and processing, we construct a multi‐frequency Ps (5, 8, 10 s) and Sp (10, 15 s) RF data set from USArray recordings. The inversion is interfaced with petrological

The pore structure in a coal matrix is a dual‐porosity system where fractures and pores coexist and feature scale‐invariance properties, that would affect the occurrence and migration of coalbed methane (CBM) significantly. Therefore, it is of fundamental importance to well define complexity types and effectively characterize their assembly mechanism of pore structure in a coal matrix. Here we identify

The mechanisms of fluid penetration through the gabbroic lower crust are important for the hydration of oceanic lithosphere. In the Oman ophiolite, which preserves an entire sequence of oceanic lithosphere formed at a fast‐spreading ridge, the layered gabbros and dunites are extensively serpentinized. In this paper, we describe the characteristic textures of serpentinized troctolite and olivine gabbros

In Taiwan and other contractional tectonic wedges, there is evidence that the basal detachment is very weak and the overlying crust is relatively strong. In this study, we compute the absolute deviatoric 3‐D stress field in Taiwan using focal mechanism data and coseismic stress changes for the 1999 M7.6 Chi‐Chi earthquake. We estimate a minimum coefficient of friction of 0.3 in the upper 15 km crust

A (micro)physical understanding of the transition from frictional sliding to plastic or viscous flow has long been a challenge for earthquake cycle modeling. We have conducted ring‐shear deformation experiments on layers of simulated calcite fault gouge under conditions close to the frictional‐to‐viscous transition previously established in this material. Constant velocity (v) and v‐stepping tests

Investigating heterogeneous structures beneath active volcanoes is important for better understanding of volcanic activity and improved mitigation of volcanic risk. In central Japan, Hakone volcano has recently shown shallow earthquake swarms and deep low‐frequency earthquakes (DLFEs), which are probably related to geothermal or deep magmatic activity. In order to image the feeding system beneath this

The 1556 CE Huaxian earthquake resulted in an estimated 830,000 deaths and caused widespread devastation in the Weihe basin, China. Seismic intensities from historical accounts yield, via magnitude‐intensity relations, a commonly quoted magnitude of 8¼ to 8½. The maximum recorded shaking was confined to a zone close to the Huashan and Weinan faults, which exhibit fresh scarps up to 7‐8 m high. Recent

Potassium (K) informs on the radiogenic heat production, atmospheric composition, and volatile element depletion of the Earth and other planetary systems. Constraints on the abundance of K in the Earth, Moon, and other rocky bodies have historically hinged on K/U values measured in planetary materials, particularly comparisons of the continental crust and mid‐ocean ridge basalts (MORB), for developing

We present a high‐resolution three‐dimensional (3‐D) anisotropic P‐wave velocity (Vp) model in the northern Hikurangi margin offshore Gisborne, New Zealand, constructed by tomographic inversion of over 430,000 first arrivals recorded by a dense grid of ocean bottom seismometers. Since the study area covers a region where shallow slow slip events (SSE) occur repeatedly and the subduction of a seamount

We model the magnetic signature of rift‐related volcanism to understand the distribution and volume of magmatic activity that occurred during the breakup of Pangaea and early Atlantic opening at the Eastern North American Margin (ENAM). Along‐strike variations in the amplitude and character of the prominent East Coast Magnetic Anomaly (ECMA) suggest that the emplacement of the volcanic layers producing

The 2017 Pohang earthquake (Mw 5.4) is the largest earthquake associated with fluid injection activities. We report new characteristics of the earthquake and propose a dislocation‐type model explaining previously reported observations. We identify fault geometry by relocating the hypocenters of 1,132 events that occurred during the first three months and then resolve their source regions as the northern

We quantify sliding stability and rupture styles for a horizontal interface between an elastic layer and stiffer elastic half‐space with a free surface on top and rate‐and‐state friction on the interface. This geometry includes shallowly dipping subduction zones, landslides, and ice streams. Specific motivation comes from quasi‐periodic slow slip events on the Whillans Ice Plain in West Antarctica

Imaging silicic systems using geophysics is challenging because many interrelated factors (e.g., temperature, melt fraction, melt composition, geometry) can contribute to the measured geophysical anomaly. Joint interpretation of models from multiple geophysical methods can better constrain interpretations of the subsurface structure. Previously published resistivity and shear wave velocity (Vs) models

To better understand the fluid migration in orogenic zones and associated chemical remagnetization, we have conducted a detailed magnetic, petrographic, and strontium isotope study in an important orogenic belt of China, the Jurassic Dabashan fold and thrust belt. This belt formed by the continued collision of the North and South China blocks after the Late Triassic closure of the Paleo‐Tethys Ocean

Magnetotactic bacteria (MTB) have long fascinated geologists and biologists because they biomineralize intracellular single domain (SD) magnetite crystals within magnetosomes that are generally organized into single or multiple chains. MTB remains in the geological record (magnetofossils) are ideal magnetic carriers and are used to reconstruct paleomagnetic and paleoenvironmental information. Here

Compressional and extensional tectonics following northward plate convergences since the Miocene have formed the major surface features in Turkey, such as faulting, orogeny, etc. Despite increasing efforts in the last few decades aiming to elucidate the current architecture of the crust and mantle beneath Turkey, several issues regarding the depth extent of the deformation zones, crust‐mantle interaction

The Shanxi Rift is one of the world's largest Cenozoic continental rifts. It is one of the most earthquake prone areas in China and has volcanic activities characterized by small volumes of magma. In order to study continental rifting mechanism, intraplate volcanism, and seismicity of the Shanxi Rift, we construct a high‐resolution 3‐D lithospheric shear velocity (Vs) model with a focus of the crust

Modeling of tsunami wave propagation for forecasting focuses on the arrival time and amplitude of the earliest tsunami waves reaching coastlines. The complex later tsunami wavefield, in which scattering is predominant, poses additional hazards due to possible constructive interference of coherent packets of wave energy. However, almost no data sets exist to characterize the geographical sources and

Geological faults may produce earthquakes under induced stresses associated with hydrocarbon extraction, geothermal extraction, or CO2 storage. The associated risks depend on the frequency and magnitude of these earthquakes. Within seismic risk analysis, the exceedance probability of seismic moments, , is treated as a pure power law distribution, , where the power law exponent, β, may vary in time

The Svalbard margin represents one of the northernmost gas hydrate provinces worldwide. Vestnesa Ridge (VR) and Svyatogor Ridge (SR) west of Svalbard are two prominent sediment drifts showing abundant pockmarks and sites of seismic chimney structures. Some of these sites at VR are associated with active gas venting and were the focus of drilling and coring with the seafloor‐deployed MARUM‐MeBo70 rig

Enhanced Geothermal Systems could provide a substantial contribution to the global energy demand if their implementation could overcome inherent challenges. Examples are insufficient created permeability, early thermal breakthrough, and unacceptable induced seismicity. Here we report on the seismic response of a meso‐scale hydraulic fracturing experiment performed at 1.5 km depth at the Sanford Underground

Both magmatic and tectonic processes contribute to the formation of volcanic continental margins. Such margins are thought to undergo extension across a narrow zone of lithospheric thinning (~100 km). New observations based on existing and reprocessed data from the Eastern North American Margin contradict this hypothesis. With ~64,000 km of 2‐D seismic data tied to 40 wells combined with published

Anisotropy of Magnetic Susceptibility (AMS) is a valid tool to investigate magma flow direction within dikes. However, geometrically inverse magnetic fabric characterized by maximum magnetic susceptibility axis (kmax) perpendicular to the dike wall may complicate the interpretation of flow trajectories. To better understand the nature of this fabric, we present a multiscale study on 19 dikes (383 samples)

We analyzed continuous GPS data collected from 2002–2020 to characterize slow slip events (SSEs) in and near the Nicoya Peninsula, Costa Rica. These data are bisected by the 5 September 2012 Mw 7.6 earthquake. The displacement time series contain multiple signals, including plate convergence, plate interface locking, coseismic and postseismic deformation, seasonal oscillations, SSEs, and noise. GPS‐measured

The Salton Trough is one of the few regions on Earth where rifting is subaerial instead of submarine. We use the relative attenuation of teleseismic P phases recorded by the Salton Trough Seismic Imaging Project to investigate lithospheric and asthenospheric structures that form during extension. Map‐view analysis reveals stronger attenuation within the Salton Trough than in the adjacent provinces

Geophysical techniques are often implemented as quick and inexpensive ways to locate and characterize fractures in the subsurface, which is important for a number of geoscience fields. Seismic velocities are the most widely used proxies for identification of fractures, but the correlation is not always well defined. Here we present material property data: unconfined compressive strength, bulk density

Iron nitrides are possible constituents of the cores of Earth and other terrestrial planets. Pressure‐induced magnetic changes in iron nitrides and effects on compressibility remain poorly understood. Here we report synchrotron X‐ray emission spectroscopy (XES) and X‐ray diffraction (XRD) results for ε‐Fe7N3 and γ′‐Fe4N up to 60 GPa at 300 K. The XES spectra reveal completion of high‐ to low‐spin transition

Shallowly dipping (<30°) low‐angle normal faults (LANFs) have been documented globally; however, examples of active LANFs in continental settings are limited. The western margin of the Panamint Range in eastern California is defined by a LANF that dips west beneath Panamint Valley and has evidence of Quaternary motion. In addition, high‐angle dextral‐oblique normal faults displace middle to late Quaternary

The presence of pressurized fluids influences the mechanical behavior of faults. To test the roles of normal stress and fluid pressure on shear strength and localization behavior of calcite gouges, we conducted a series of rotary‐shear experiments with pore fluid pressures up to 10.5 MPa and difference between normal stress and fluid pressure up to 11.2 MPa. Calcite gouges were sheared for displacements