Strain weakening leads to the formation of high-strain shear zones and strongly influences terrestrial ice discharge. In glacial flow models, strain weakening is assumed to arise from the alignment of weak basal planes—the development of a crystallographic preferred orientation, CPO—during flow. However, in experiments, ice strain weakening also coincides with grain size reduction, which has been invoked

Tectonic and surface processes (e.g., erosion) act in concert to denude and flatten elevated topography during and following collisional uplift. In orogens that collapsed rapidly (<10 Myr), the effectiveness and relative contribution of erosion remains poorly understood. Here, we use 1-D and 2-D finite-difference models to test plausible magnitudes of erosion during denudation of the Scandian orogenic

High electrical conductivity in the shallow mantle has long been recognized by electromagnetic depth soundings, but the origin remains debated. Various candidates, of which the two most popular are water enrichment in olivine (the dominant mineral in the upper mantle) and partial melt, have been proposed to explain the electrical anomalies. These models nearly exclusively assume a very low conductivity

This contribution presents an early-time solution for permeability evaluation in pulse-decay tests. A nonlinear governing equation for gas transport in the sample is derived considering the pressure dependence of gas compressibility and Klinkenberg slippage effect, and the early-time solution is obtained through the integral balance analysis. The permeability coefficient can be determined by the proposed

Seismic attenuation is generally greater in the western United States (WUS) than the central and eastern United States (CEUS), but the nature of this transition or location of this boundary is poorly constrained. We conduct crustal seismic (Lg) attenuation tomography across a region that stretches from the CEUS across the Rocky Mountains to the Basin and Range using a total of 115,870 amplitude measurements

Integration of multiple geophysical data is a key practice to reduce model uncertainties and enhance geological interpretations. Electrical resistivity models resulting from inversion of marine magnetotelluric (MT) data, often lack depth resolution of lithological boundaries and distinct information for shallow model parts. This is due to the diffusive nature of electromagnetic fields, enhanced by

Percolation theory is often proposed as a framework for understanding flow and transport through fractured rock, yet the applicability of percolation theory to natural systems remains uncertain. Experimental verification of the predictions of percolation theory are challenging because of the difficulty in systematically creating 3D crack networks in crystalline materials. Using ice as a model for rock

Debate abounds regarding the composition of the deep (middle + lower) continental crust. Exhumed medium- and high-grade metamorphic rocks, which range in composition from mafic to felsic, provide information about the bulk composition of the deep crust. This study presents a global compilation of geochemical data on amphibolite (n = 6,500), granulite (n = 4,000), and eclogite (n = 200) facies lithologies

Studies of the high-pressure (HP) As Sifah eclogites in the NE Saih Hatat Window, Oman, have used different combinations of radiometric dating results (Ar/Ar, Sm-Nd vs. U-Pb, Rb-Sr) to interpret disparate tectonic models for the timing, geometry, and cause of continental subduction—including its relationship to the Samail Ophiolite. To determine the timing of continental subduction, we coupled petrochronological

An explosive sound was heard over a wide area of Sapporo city, Hokkaido, Japan, on 26 April 2021. It was accompanied by minor shaking and was considered likely to be a sonic boom produced by a fireball. However, no luminous phenomenon was observed. We analyzed seismic data to identify the source of the sonic boom, and estimated the trajectory of the object from the associated signal arrival times.

The Alpine Fault zone in New Zealand marks a major transpressional plate boundary that is late in its typical earthquake cycle. Understanding the subsurface structures is crucial to understand the tectonic processes taking place. A unique seismic survey including 2D lines, a 3D array, and borehole recordings, has been performed in the Whataroa Valley and provides new insights into the Alpine Fault

Present-day seismic imaging, reveals crustal thickness varying from about 70 km under SongPan-Ganzi (SG) to about 50 km under Qaidam basin (QB) terranes in NE Tibet. This vertical Moho offset occurs over horizontal spans of less than 20 km, and is somehow confirmed by gravimetric and electromagnetic observations. Paleotectonic and litho-stratigraphic reconstructions suggest that the region amalgamates

Subduction interface thermal structure changes drastically within the first few million years of underthrusting (i.e., subduction infancy). Metamorphic soles beneath ophiolites record snapshots of dynamic conditions and mechanical coupling during subduction infancy. Beneath the Samail Ophiolite (Oman), the sole comprises structurally higher high-temperature (HT) and lower low-temperature (LT) units

Dike swarms are the fossil remains of regions of the crust that have undergone repeated magma injections. Volcanic earthquake swarms and geodetic measurements are, at least in part, a record of active injection of fluids (water, gas, or magma) into fractures. Here, we link these two ways of observing magmatic systems by noting that dike thicknesses and earthquake magnitudes share similar scaling parameters

The Oman Drilling Project “Multi-Borehole Observatory” (MBO) samples an area of active weathering of tectonically exposed peridotite. This paper reviews the geology of the MBO region, summarizes recent research, and provides new data constraining ongoing alteration. Host rocks are partially to completely serpentinized, residual mantle harzburgites and replacive. Dunites show evidence for “reactive

We present a systematic model that links the generation, migration, phase partitioning and accumulation of methane into a closed loop as the sediment is deposited from the seafloor and buried through the base of hydrate stability zone (BHSZ). In our model, methane is generated by biodegradation of organic carbon in muds. Hydrate does not form and methane is not trapped until a coarse-grained layer

Strong ground motions from large earthquakes are capable of damaging near-surface sediments and promoting notable reductions in their seismic velocity structures. These velocity reductions can be monitored using either body waves or surface waves from repeatable seismic sources, such as repeating earthquakes or ambient seismic noise. Here we compile a decade-long catalog of repeating earthquakes since

We present a 2D thermo-elastic model of a magma body formation in a granitic crust by injection of rhyolitic or basaltic dikes and sills. Elastic analytical solutions enable the computation of rock displacement in response to magma intrusion and evacuation during volcanic eruptions. Phase diagrams for magma and rocks govern melting/crystallization behavior and temperature evolution in 16 million computational

Bridgmanite may contain a large proportion of ferric iron in its crystal structure in the forms of FeFeO3 and MgFeO2.5 components. We investigated the pressure dependence of FeFeO3 and MgFeO2.5 contents in bridgmanite coexisting with MgFe2O4-phase and with or without ferropericlase in the MgO-SiO2-Fe2O3 ternary system at 2,300 K, 33 and 40 GPa. Together with the experiments at 27 GPa reported in Fei

A large part of the hydrated oceanic lithosphere consists of serpentinites exposed in ophiolites. Serpentinites constitute reactive chemical and thermal systems and potentially represent an effective sink for CO2. Understanding carbonation mechanisms within ophiolites is almost exclusively based on studies of outcrops, which can limit the interpretation of fossil hydrothermal systems. We present stable

Some spherical harmonic expressions (SHEs) of gravitational and geomagnetic field elements will become infinite when computation point approaches polar regions, as the sine function of the co-latitude contained in the denominator tends to be zero. Currently, this singularity problem has been solved for gravitational field case, however, it remains unsolved for geomagnetic vectors (GVs) and geomagnetic

Using E-W and vertical deformation-rate maps derived from radar interferometric time-series, we analyze the deformation field of an entire orogenic segment, i.e., the Tajik depression and its adjoining mountain belts, Tian Shan, Pamir, and Hindu Kush. The data-base consists of 900+ radar scenes acquired over 2.0–4.5 years and global navigation satellite system measurements. The recent, supra-regional

Monitoring changes of seismic properties at depth can provide a first order insight into Earth’s dynamic evolution. Coda wave interferometry is the primary tool for this purpose. This technique exploits small changes of waveforms in the seismic coda and relates them to temporal variations of attenuation or velocity at depth. While most existing studies assume statistically homogeneous scattering strength

The transition from the Semail ophiolite mantle to the underlying metamorphic sole was drilled at ICDP OmanDP Hole BT1B. We analyzed the bulk major, volatile and trace element compositions of the mantle-derived listvenite series and metamorphic rocks, with the aim to constrain chemical transfers associated with peridotite carbonation along the ophiolite basal thrust. The listvenite series comprise

Reconstructions of the geomagnetic field on long timescales are important to understand the geodynamo processes in the Earth’s core. The geomagnetic field exhibits a range of variations that vary from normal, dipole–dominated secular variation to geomagnetic excursions and reversals. These transitional events are associated with significant directional deviations and very low intensities. Here we present

Induced earthquake sequences are typically interpreted through causal triggering mechanisms. However, studies of causality rarely consider large regions and why some regions experiencing similar anthropogenic activities remain largely aseismic. Therefore, it can be difficult to forecast seismic hazard at a regional scale. In contrast, multivariate statistical methods allow us to find the combinations

Characterizing and modeling melting relations in the system MgO-SiO2 at lower mantle pressures rely on the location of the eutectic points for MgO-MgSiO3 and MgSiO3-SiO2. While at an uppermost lower mantle pressure there is general consensus on the eutectic composition in the former, large discrepancies exist for MgSiO3-SiO2 from experiments in the diamond anvil cell, ab-initio simulations and models

We investigate the origin of a long-lived earthquake cluster in the Fars arc of the Zagros Simply Folded Belt that is colocated with the major Shanul natural gas field. The cluster emerged in January 2019 and initially comprised small events of Mn ∼ 3–4. It culminated on 9 June 2020 with a pair of Mw 5.4 and 5.7 earthquakes, which was followed by >100 aftershocks. We assess the spatiotemporal evolution

The 700-km-long Chaman fault (CF) marks the western edge of the plate boundary between India and Eurasia. Although global plate models predict 2.3–3.6 cm/yr left-lateral motion between both plates, the fault is known to have hosted few earthquakes in historical times. Recent geodetic measurements attested the presence of aseismic slip locally. To detail the interplay between fast and slow slip along

Fluid flow through geological formations is often concentrated on distinct preferential flow paths owing to the presence of fractures or large-scale permeability structures. However, the existence of such structures is not a mandatory condition of preferential paths formation. Pore-scale spatial fluctuations of pore size and/or pore connectivity in statistically stationary porous media, if sufficiently

Ocean-generated seismic waves are omnipresent in passive seismic records around the world and present both a challenge for earthquake observations and an input signal for interferometric methods for characterization of the Earth's interior. Understanding of these waves requires the knowledge of the depth dependence of the oceanic noise at the transition into the continent. To this end, we examine 80 days

We present new P and S teleseismic tomography models of the upper mantle beneath California and Nevada. Improved tomographic methods and the incorporation of new data increase image resolution and seismic structure definition. Technical advancements include the use of 3-D ray tracing, ray weighting and finite-frequency sensitivity kernels. Together with the incorporation of modern crustal velocity

Fiber optic distributed acoustic sensors (DAS) are becoming a widely used tool for seismic sensing. Here we examine recordings of two subsurface chemical explosions, DAG-1 and DAG-3, each of which was about one metric ton (TNT equivalent), that were recorded from a helical fiber installed in two boreholes 80 m away from the source location. Several clear phases including the initial P wave, a weak

Improving our understanding of the relation between the water content and the seismic signatures of unconsolidated superficial soils is an important objective in the overall field of hydrogeophysics. Current approaches to constrain the water content in the vadose zone from seismic data are based on computing the ratio between compressional and shear wave velocities Vp/Vs. While this allows for the

Earthquake slip distributions help constrain rupture behavior and return times. Here, by combining 0.5-m-resolution image and topographic data interpretation with fieldwork, we quantify the co-seismic throw distribution and rupture geometry of the 1609 Hongyazi earthquake along the Qilian Shan Fodongmiao fontal thrust (NE Tibet). We measured 396 vertical offsets across mapped geomorphic units along

The 2008 Mw7.9 Wenchuan earthquake ruptured northwest-dipping imbricate oblique reverse faults along the Longmenshan thrust belt at the eastern margin of the Tibetan Plateau, and developed one of the most complex coseismic rupture patterns for reverse faulting events ever reported in intraplate settings. To evaluate to what extent complex fault geometry and heterogeneities in initial stress can explain

We quantified mineral proportions in listvenite (completely carbonated peridotite) in Hole BT1B drilled across the basal thrust of the Samail ophiolite by the International Continental Scientific Drilling Project Oman Drilling Project using 3D X-ray Computed Tomography (XCT). We analyzed >250,000 XCT images from a continuous ∼200 m listvenite core. Histograms of the intensity of X-ray attenuation of

Sparse wide-angle seismic profiling supported by coincident reflection imaging has been instrumental for advancing our knowledge about rifted margins. Nevertheless, features of critical importance for understanding rifting processes have been poorly resolved. We derive a high-resolution velocity model by applying full waveform inversion to the dense OETR-2009 wide-angle seismic profile crossing the

Time-lapse or 4D seismic survey is a crucial monitoring tool for CO2 geological sequestration. Conventional time-lapse interpretation provides detailed characterization of CO2 distribution in the storage unit. However, manual interpretation is labor-intensive and often inconsistent throughout the long monitoring history, due to the inevitable changes in seismic acquisition and processing technology

The exploration and exploitation of shale oil is an important aspect in the oil industry. Seismic properties and well-log data are essential to establish wave-propagation models. Specifically, the description of wave dispersion and attenuation under complex geological conditions needs proper lithological and petrophysical information. This complex physical mechanism has to be considered if a traditional

Induced earthquakes caused by hydraulic fracturing (HF) are a growing concern, with risks that are often managed by traffic light protocols (TLPs). Here, we apply a risk-informed strategy for choosing TLP red-light thresholds. We utilize a combination of probabilistic maximum magnitudes, formation depth, site amplification, ground motion relationships, felt/damaging shaking tolerances, and population

Deep low-frequency earthquakes (LFEs) in Northeast Japan occur beneath active volcanoes at depths of 10–40 km. These volcanic LFEs radiate low-frequency seismic waves, with most energy at 2–8 Hz, despite their low magnitudes (M < 2). Although many previous studies have obtained various focal mechanisms with non-double-couple components and suggested physical processes related to magma, the universal

Semi-brittle flow occurs when crystal plasticity and cataclastic mechanisms operate concurrently and may be common at mid-levels of the Earth’s crust. Using a Paterson gas-deformation apparatus, we performed 67 conventional triaxial deformation experiments on dry samples of Carrara marble in the temperature range of T = 20 - 800°C; confining pressures (PC) were 30, 50 100, 200, and 300 MPa, and strain

Petrographic and major element investigations of carbonates from seven drill cores recovered during IODP Expedition 357 on the Atlantis Massif (AM) provide information on the genesis of carbonate minerals in the oceanic lithosphere. Textural sequences and mineralogical assemblages reveal three distinct types of carbonate occurrences in ultramafic rocks that are controlled by (a) fluid composition and

Accuracy of hypocenter location, in particular focal depth, is a precondition for high-resolution seismotectonic analysis of natural and induced seismicity. For instance, linking seismicity with mapped fault segments requires hypocenter accuracy at the sub-kilometer scale. In this study, we demonstrate that inaccurate velocity models and improper phase selection can bias absolute hypocenter locations

We present a novel methodology for exploring 4D seismic data in the context of monitoring subsurface resources. Data-space exploration is a key activity in scientific research, but it has long been overlooked in favor of model-space investigations. Our methodology performs a data-space exploration that aims to define structures in the covariance matrix of the observational errors. It is based on Bayesian

Hematite carries magnetic signals of interest in tectonic, paleoclimatic, paleomagnetic, and planetary studies. First-order reversal curve (FORC) diagrams have become an important tool for assessing the domain state of, and magnetostatic interactions among, magnetic particles in such studies. We present here FORC diagrams for diverse hematite samples, which provide a catalog for comparison with other

We invert daily GNSS vertical position time series for terrestrial water storage (TWS) changes and characterize their spatiotemporal patterns using various geodetic and hydrological data in Sichuan which features complex climatic and geographical conditions. Our inversion strategy depends on a variational Bayesian principal component analysis (VBPCA), which recovers the equivalent water height (EWH)

Peridotites of Ulten Zone (Eastern Alps, N Italy) show a transition from coarse protogranular spinel lherzolites to fine-grained amphibole + garnet peridotites, recorded by the crystallization of garnet coronas around spinel. Pyroxenite veins, transposed along the peridotite foliation, show a similar metamorphic evolution from coarse-grained (garnet-free) websterites to fine-grained garnet websterites

The breakup of supercontinent Pangea occurred ∼200 Ma forming the Eastern North American Margin (ENAM). Yet, the precise timing and mechanics of breakup and onset of seafloor spreading remain poorly constrained. We investigate the relict lithosphere offshore eastern North America using ambient-noise Rayleigh-wave phase velocity (12–32 s) and azimuthal anisotropy (17–32 s) at the ENAM Community Seismic

The electrical resistivity-porosity relationship of porous media is critical for reliable formation evaluation. Archie’s equation is empirical, and uses only porosity as pore-space property, neglecting the spatial variability of the pore space; its fitting parameters may have unclear physical meaning and be non-constant over a wider porosity range or in spatially complex rocks. We use microfluidics

The Pamir Frontal Thrust (PFT) of the Trans-Alai Range in Central Asia is the principal active fault of the intracontinental convergence zone between the Pamir and Tien Shan. Its northward propagation is reflected by frequent seismic activity and ongoing crustal shortening. Recent and historic earthquakes exhibit complex rupture patterns within and across seismotectonic segments bounding the Trans

GRACE and GRACE-FO gravimetry data is unique in its ability to observe global water mass variability, and has frequently been applied for the determination of global mass rates for quantifying the impacts of climate change and human activity on global freshwater availability and land ice evolution. However, its relatively coarse spatial resolution of ∼300-500 km at monthly intervals precludes its direct

In Southeast Alaska, extreme uplift rates are primarily caused by glacial isostatic adjustment (GIA), as a result of ice thickness changes from the Little Ice Age to the present combined with a low-viscosity asthenosphere. Previous GIA models adopted a 1-D Earth structure. However, the actual Earth structure is likely more complex due to the long history of subduction and tectonism and the transition

No abstract is available for this article.

The interconnection between anthropogenic and natural surface loads and seismicity continues to be poorly understood. The metropolitan Salt Lake City (SLC) in Utah hosts various industrial, hydrological, and tectonic processes, including the Bingham Canyon mine and its associated tailings facility, precipitation and water storage at the surface and in aquifers, as well as the seismically active Wasatch

In southcentral Alaska, the Alaska-Aleutian Wadati-Benioff zone (WBZ) shows high seismicity rates west of 147°W. Further east, the Wrangell volcanic field (WVF) has some of the world's largest continental volcanoes but there is equivocal evidence for a WBZ. We deployed a dense seismometer array around the WVF between 2016 and 2018 and used the data to increase the number of detected earthquakes using

Studies of glacial isostatic adjustment (GIA) often use paleoshorelines and present-day deformation to constrain the viscosity of the mantle and the thickness of the elastic lithosphere. However, several studies focused on similar locations have resulted in different estimates of these physical properties. We argue that these different estimates infer apparent viscosities and apparent lithospheric

Although tremor is believed to consist of myriad low-frequency earthquakes (LFEs), it also contains longer-period signals of unknown origin. We investigate the source of some of the longer-period signals by locating tremor windows independently in relatively high-frequency (“HF”, 1.25–6.5 Hz, containing typical LFEs) and low-frequency (“LF”, 0.5–1.25 Hz) bands. We hypothesize that if tremor consists

We show that direct estimates of the permeability of hydrate-bearing geological formations are possible from remote measurements of shear wave velocity (Vs) and attenuation (Qs−1). We measured Vs, Qs−1 and electrical resistivity at time intervals during methane hydrate formation in Berea sandstone using a laboratory ultrasonic pulse-echo system. We observed that Vs and Qs−1 both increase with hydrate