In March and May 2021, Mw7.0 and Mw6.7, respectively, deep interplate earthquakes occurred off Miyagi, Japan, near the downdip edge of the rupture area of the 2011 M9 Tohoku earthquake. We study the two Mw∼7 earthquakes to investigate how a great (Mw∼9) earthquake cycle impacts the generation of smaller (Mw7-8) earthquakes in the deep seismic/aseismic transition zone. Our hypocenter relocation results

The anisotropy of magnetic susceptibility of ferrofluid-impregnated samples is an efficient and powerful proxy for pore space anisotropy and preferred flow directions. One of the main assumptions in pore fabric studies is that all pores > 10-20 nm are homogeneously filled with ferrofluid, and that the ferrofluid has constant properties throughout the pore space and over time. If only part of the pore

If brittle fault strength depends only on friction, slip instability is discouraged at low effective normal stress, σ. Stress drop and the critical stiffness necessary for unstable sliding both vanish with σ; small earthquakes cannot occur. Very low σ is inferred in the source region of low frequency earthquakes (LFEs) on the San Andreas fault (SAF). Moreover, if pore pressure, p, is undrained at low

Geoid is a key observable for understanding the dynamics of the deep Earth, but has been considered largely transparent to long-wavelength shallow density structures, especially those of the cratonic lithosphere. Here, we demonstrate that the observed flat craton-ocean geoid pattern, traditionally interpreted as reflecting neutrally buoyant cratonic keels, provides critical constraints on both the

Various indices have been defined to characterize the phase and amplitude of the Madden-Julian oscillation (MJO). One widely used index is the outgoing longwave radiation (OLR) based MJO index (OMI), which is calculated using the spatial pattern of 30–96-day eastward-filtered OLR. The empirical orthogonal functions (EOFs) used to calculate the OMI in observations are prone to degeneracy and exhibit

The compositional similarity between high-Mg andesite-dacite from accretionary orogens and bulk continental crust (CC) provides an opportunity to unravel the CC formation paradox. Compositional data from a global compilation of Quaternary magmatic arcs indicate the presence of low-Mg series (LMS) and high-Mg series (HMS). The LMS show trends of crystal fractionation and can be subdivided into high

Because downscaling methods can yield substantially different projections of future climate, it is imperative to constrain these projections with information from existing observations, while also recognizing observational uncertainty. California is a natural test case to develop observational constraints on future projections given prior studies that have purportedly found contrasting spatial patterns

We analyze and compare changes in ocean acidification metrics caused by anthropogenic carbon (Canth) accumulation in the North Pacific Ocean and California Current Large Marine Ecosystem (CCLME). The greatest declines in pH and carbonate mineral saturation state occur near the surface, coincident with the highest Canth concentrations. However, maximal increases in the partial pressure of carbon dioxide

Subducted oceanic crust is enriched in free silica. Although being one of the silica polymorphs at lower-mantle pressures, niccolite-type phase (Nt-phase) has not been documented in multicomponent metabasaltic or metasediment compositions relevant to subducting oceanic crust. Here, we report the formation of an Al-rich Nt-phase (∼24.4 to 32.4 wt% Al2O3), coexisting with Al-depleted bridgmanite (∼6

The Earth's magnetosheath (MSH) is governed by numerous physical processes which shape the particle velocity distributions and contribute to the heating of the plasma. Among them are whistler waves which can interact with electrons. We investigate whistler waves detected in the quasi-parallel MSH by NASA's Magnetospheric Multiscale mission. We find that the whistler waves occur even in regions that

We report observations of stimulated electromagnetic emission (SEE) induced by high power high frequency (HF) radio waves near the third electron gyroharmonic (3) at European Incoherent Scatter Radar (EISCAT). It is discovered that stimulated Brillouin scattering (SBS) spectrum behaves similarly as spectral ion lines of the incoherent scatter radar (ISR) for HF pumping frequency above 3. The SBS spectral

Ice and other mineral cements in Mars' shallow subsurface affect the mechanical properties of the shallow crust, the geologic processes that shape the planet's surface, and the search for past or extant Martian life. Cements increase seismic velocities. We use rock physics models to infer cement properties from seismic velocities. Model results confirm that the upper 300 m of Mars beneath InSight is

Many described subduction complexes (or mélanges) exhumed from seismogenic depths comprise thick, turbidite-dominated sequences with deformed zones containing clasts or boudins of more competent sandstone and/or basalt. In contrast, many active subduction zones have a relatively small thickness of sedimentary inputs ( < 2 km), turbidite sequences are commonly accreted rather than subducted, and the

Morphological processes often induce meter-scale elevation changes. When a volcano erupts, tracking such processes provides insights into the style and evolution of eruptive activity and related hazards. Compared to optical remote-sensing products, Synthetic Aperture Radar (SAR) observes surface change during inclement weather and at night. Differential SAR interferometry estimates phase change between

Mars’ ultraviolet dayglow has been used to study its upper atmosphere for over four decades. Identifying variations in emission features has provided information on composition, density and temperature. The Emirates Mars Ultraviolet Spectrometer onboard the Emirates Mars Mission observes Mars’ dayglow at Far and Extreme UV wavelengths. Variations in disk emission features are studied, with a focus

Based on statistical analysis using observations and idealized model simulations, previous studies have revealed the potential response of early-winter atmospheric circulation and temperature anomalies to November Ural blocking (UB) anomalies. Using a large number of coupled simulations, this study found that the response is sensitive to the intensity of November mid-latitude westerly jet over Eurasia

We present improvements in the modeling of the vertical wavenumber spectrum of the internal gravity wave continuum in high-resolution regional ocean simulations. We focus on model sensitivities to mixing parameters and comparisons to McLane moored profiler observations in a Pacific region near the Hawaiian Ridge, which features strong semidiurnal tidal beams. In these simulations, the modeled continuum

The Bayesian Model Averaging (BMA) method has been widely used for generating probabilistic climate projections. However, the averaging weights used in BMA can only reflect the spatially- and temporally-averaged performance of each ensemble member, without the ability to address the spatiotemporal variations of model biases. This can lead to inevitable exaggeration or understatement of the contributions

This study examined synoptic impacts on the occurrence of boundaries and their associated convection during summers from 2012–2016 over Hetao Irrigation District in North China, where there is a sharp vegetation contrast. Objective classification showed that boundary days, especially convective boundary days, were more frequent under a mid-troposphere, high-pressure ridge or pre-trough pattern. Such

Thick eolian loess sequences in arid Central Asia (CA) contain a wealth of information on the intensity variations of mid-latitude westerlies and the aridification history of the nearby deserts. In this study, detailed lithologic and magnetostratigraphic investigations suggest that loess deposits on the western margin of the Pamir Plateau began to accumulate at around 2.7 Ma, representing the most

Real-time monitoring of the microbial activity in porous media faces considerable challenges because conventional analytical procedures are intrusive. Induced polarization (IP) has shown promises as a non-intrusive monitoring approach for such processes. However, quantitative analysis of soil column experiments to show how IP-based parameters can be related to the density of bacteria is still lacking

The extension of back-arc basins and formation of marginal seas following the subduction of oceanic lithosphere are usually attributed to the rollback of subducting slabs and distorted mantle convection. However, for the Japan Sea, the largest marginal sea in the northwestern Pacific, its opening is unlikely only resulted from the subduction of the Pacific plate because of the coeval Philippine plate

Under the context of global warming, we identified a significant increase in lightning activity in the last two decades over the Tibetan Plateau (TP), the highest and largest plateau on earth, based on two datasets. The largest rise of lightning activity was found over the region with high lightning density represented by the eastern TP at a rate of 0.072±0.069 fl km-2 yr-1 during 1996-2013 from OTD/LIS

Distributed Acoustic Sensing (DAS) has become a popular method of observing seismic wavefields: backscattered pulses of light reveal strains or strain-rates at any location along a fiber-optic cable. In contrast, a few newer systems transmit light through a cable and collect integrated phase delays over the entire cable, such as the Microwave Frequency Fiber Interferometer (MFFI). These integrated

Magnetic reconnection has been observed in the transition region of quasi-parallel shocks. In this work, the particle-in-cell method is used to simulate three-dimensional reconnection in a quasi-parallel shock. The shock transition region is turbulent, leading to the formation of reconnecting current sheets with various orientations. Two reconnection sites with weak and strong guide fields are studied

The Indian Ocean Dipole (IOD) is the predominant interannual climate mode and is critical in regulating the biogeochemical cycles of the equatorial Indian Ocean (EIO). However, the dynamics of nutrient supply and the magnitude of biological responses are less understood. Here, by comparing the biophysical in situ observations across the eastern EIO during the decaying period of an positive IOD in 2019

The carbon and water cycles in the Earth’s interior are linked to key planetary processes, such as mantle melting, degassing, chemical differentiation, and advection. However, the role of water in the carbon exchange between the mantle and core is not well known. Here, we show experimental results of a reaction between Fe3C and H2O at pressures and temperatures of the deep mantle and core-mantle boundary

Looping patterns, where channels divide and reconnect further downstream, are widespread in natural rivers. Here, we build an extensive dataset of different gravel-bed and sand-bed rivers around the world encompassing a wide range of physiographic and sedimentological conditions. Field data show the existence of quasi-universal relations for the anabranches length when scaled with bankfull hydraulic

A newly developing method, optically stimulated luminescence (OSL)-depth profiles (DPs), provides a novel means of reconstructing and quantifying fault slip on timescales of 101–4 years. A targeted bedrock fault scarp along Langshan in north China, used as proof of concept, is divided into four sections based on four groups of OSL-DPs at different heights up the bedrock fault scarp. These have seismic

Enigmatic large-scale ( > 150 km wide) ground deformation in southern Bolivia has been ongoing for more than 50 years. Concurrent changes in gravity recorded between 2010 and 2018 imply minor changes in subsurface density in the absence of significant mass changes. Numerical modelling of the gravity changes and concurrent InSAR LOS displacements gives annual bulk density changes of 0.002 kg m−3 in

Mesoscale processes make the largest contribution to ocean variability and are significant agents in ocean heat transport. In this investigation, we provide evidence based on satellite observations for an increasing trend in surface transient eddy heat flux (EHF) over the period 1993–2020. The enhanced EHF is particularly prominent in western boundary currents and their extensions at mid-latitudes

Anthropogenic emission is an important component of the present-day iron cycle yet its long-term impacts on climate are poorly understood. Iron mineralogy strongly affects its radiative and oceanic interactions and was unrepresented in previous studies. We perform simulations using a mineralogy-based inventory and an atmospheric transport model and estimate the 1850-to-2010 global mean direct radiative

Surface winds around the Antarctic continent control coupled ocean-ice processes that influence the climate system, including bottom water production, heat transport onto the continental shelf and sea ice coverage. However, few studies have examined projected changes in these winds, even though it would aid in the interpretation and understanding of the ocean’s response to climate change. Using Coupled

The decay of the primordial isotopes 238U, 235U, 232Th, and 40K have contributed to the terrestrial heat budget throughout the Earth’s history. Hence the individual abundance of those isotopes are key parameters in reconstructing contemporary Earth models. The geoneutrinos produced by the radioactive decays of uranium and thorium have been observed with the Kamioka Liquid-Scintillator Antineutrino

Single-crystal elasticity of both α- and β-orthopyroxene was determined up to 20 GPa and 300 K by Brillouin scattering. Using the derived full elastic moduli (Cij), we investigated the contribution of the metastable pyroxene to the seismically-observed 3-5% low-velocity anomalies along the subducting slab in the top transition zone. Our modelled results show that a harzburgite wedge with a 1000-K colder

This paper investigates the impacts of extratropical Pacific on El Niño-Southern Oscillation (ENSO) spring predictability barrier (SPB). Using an empirical dynamical model - Linear Inverse Model (LIM), we find that the dynamics of the northern and southern extratropical Pacific can significantly and equally weaken the Eastern Pacific (EP)-ENSO SPB, while the North Pacific is more important for weakening

We experimentally investigate the depth distributions and dynamics of air bubbles entrained by breaking waves in a wind-wave channel over a range of breaking wave conditions using high-resolution imaging and three-dimensional bubble tracking. Below the wave troughs, the bubble concentration decays exponentially with depth. Patches of entrained bubbles are identified for each breaking wave, and statistics

The continental collision and subduction between the North China Craton and Yangtze Plate resulted in complex multistage tectonic episodes of the Tanlu fault zone. To adequately understand the geodynamic processes of the continental collision, we construct a high-resolution shear-wave velocity model of the crust and uppermost mantle using full-wave ambient noise tomographic method based on a new broadband

Heatwaves pose severe threats to human health, especially those combining heat and humidity. Here, we use dry- and wet-bulb temperatures as indicators to classify dry and humid heatwaves in southern China and distinguish their different mechanisms. We find that both dry and humid heatwaves are accompanied by an eastward extension of the South Asian high, a westward extension of the western North Pacific

Several large strike slip faults in central and northern California accommodate plate motions through aseismic creep. Although there is no consensus regarding the underlying cause of aseismic creep, aqueous fluids and mechanically weak, velocity-strengthening minerals appear to play a central role. This study integrates field observations and thermodynamic modeling to examine possible relationships

The sudden eruption of the Tonga underwater volcano (20.53°S, 175.38°W) on 15 January 2022 generated explosions that triggered blast waves traveling away from the eruption. In this study, the analysis of the geomagnetic field observations on the ground shows that the eruption perturbed the E-region current density by 22–55 mA/m within a radius of 8,000 km away from the eruption. The perturbation evolved

Recent soil moisture (SM) reconstructions revealed plunging trends and enhanced SM-temperature couplings over the last two decades in dry regions. However, how SM changed and whether the land-atmosphere interaction was intensified over time in humid regions remained unknown. Here we reported the first six-century-long regional summer SM reconstruction (1360–2000 CE) in western Europe (WE) using three

The Tonga volcano eruption of 15 January 2022 unleashed a variety of atmospheric perturbations, coinciding with the recovery-phase of a geomagnetic storm. The ensuing thermospheric variations created rare display of extreme poleward-expanding conjugate plasma bubbles seen in the rate of total electron content index over 100–150°E, reaching ∼40°N geographic latitude. This is associated with fluctuations

We conduct a high-resolution teleseismic receiver function investigation of the subducting plate interface within the Alaskan forearc beneath Kodiak Island using data collected as part of the Alaska Amphibious Community Seismic Experiment in 2019. The Kodiak node array consisted of 398 nodal geophones deployed at ∼200–300 m spacing on northeastern Kodiak Island within the southern asperity of the 1964

We present a high-resolution P-wave azimuthally anisotropic velocity model for the upper and middle crust beneath southern California by a novel adjoint-state traveltime tomography technique. Our model reveals significant anisotropy variations between tectonic blocks that clearly reflect both past and current plate boundary deformation. In the shallow crust, seismic anisotropy is mostly controlled

The unusually prolonged volcanism at the Chang'e-5 (CE-5) landing site remains a mystery. To constrain the geochemical features of the CE-5 mantle source, we performed in situ sulfur isotope analysis on sulfides of the CE-5 basalts. The modal abundance of sulfides is ∼0.1 wt%, dominated by troilite with trace cubanite, chalcopyrite and pentlandite, yielding a S-abundance of ∼360 ± 180 ppm for the bulk

NASA satellite measurements show that ozone reductions throughout the Northern Hemisphere (NH) free troposphere reported for spring-summer 2020 during the COronaVIrus Disease 2019 pandemic have occurred again in spring-summer 2021. The satellite measurements show that tropospheric column ozone (TCO) (mostly representative of the free troposphere) for 20°N–60°N during spring-summer for both 2020 and

The Central Mallorca Depression (CMD) located in the Balearic Promontory (Western Mediterranean), contains a well-preserved evaporitic sequence belonging to the Messinian Salinity Crisis (MSC) salt giant, densely covered by high- and low-resolution seismic reflection data. It has been proposed recently that the MSC evaporitic sequence in the CMD could be a non-deformed analogue of the key MSC area

ABSTRACT Seismic response of liquid sloshing in horizontally baffled rectangular container on deformable ground is evaluated. An equivalent mechanical model of baffled sloshing is developed. The strip partition method is presented to analytically derive the foundation impedances reproduced by nested lumped-parameter model. The system equations of motion are constructed via applying Hamilton’s principle

The Dianzhong Block (DZB) located on the southeastern margin of the Tibetan Plateau is an important tectonic zone characterized by the intense flow of crustal material. Although it is widely accepted that materials originating from the Tibetan Plateau migrate southeastward in the DZB and its vicinity, the flow mechanism and subsurface structures remain controversial. Here, we image the subsurface velocity

Normal faulting in orogens is usually associated with gravitational potential energy (GPE) due to elevation differences and contrasting material rheology between mountains and foreland areas. The 2008–2020 Yutian normal earthquake sequence in the West Kunlun Mountains has been closely studied over the last decade, but the mechanisms of normal faulting in the region are still an open question as both

Clast–cortex aggregates (CCAs) have been commonly reported in experimental and natural fault gouges. Here we discuss the formation process of CCAs and its mechanical implications, based on experimentally simulated fault gouges. We conducted low- to high-velocity rotary shear experiments on Ca-bentonite gouges at a normal stress of 1 MPa, slip rates of 0.01–1.31 m s−1, and ambient temperature and humidity

Fluids injection for hydraulic stimulation and fracturing, typical in the development of enhanced geothermal systems (EGS) in granites, can reactivate deep faults and induce seismicity. Such faults typically contain chlorite coatings as an alteration product that may impact styles of deformation – aseismic through seismic. We performed low velocity shear experiments on simulated granite fault gouges

Dense arrays deployed near the hydraulic-fracturing (HF) wells greatly enhance the understanding of injection-induced seismicity. In this study, we revisit the continuous recordings that are acquired by 69 three-component nodes at a HF site in Alberta, Canada, taking advantage of a machine learning-based seismic detection and location workflow (LOC-FLOW). The obtained new earthquake catalog contains

In this study, we investigate both the changes of tropical cyclone (TC) rainfall hazard in the United States under climate change and the relative importance of the factors that cause the changes. We find that under the SSP5 8.5 scenario, the 100-year TC rainfall level can increase by up to 320% along the U.S. coastline by the end of this century. The influence of TC rainfall-producing ability increase

Diurnal analyses of water ice cloud optical depths retrieved from thermal infrared spectra by the Emirates Mars Infrared Spectrometer showed changing cloud abundance throughout the Martian day. Observations began with the start of the Emirates Mars Mission science phase near the beginning of aphelion-season in Mars Year 36 and included the prominent aphelion cloud belt (ACB) and orographic clouds in

Exploration of Venus in the 1970–1990s revealed that the geology of Venus, the most Earth-like of the terrestrial planets, was decidedly un-Earth-like, with no plate tectonics, and no record of the first 80% of its history. A major outstanding question is whether Venus is still volcanically active today. We find that regions of Ganis Chasma have low radar emissivity values, due to low volumes of high

Predictable internal climate variability on decadal timescales (2–10 years) is associated with large-scale oceanic processes, however these predictable signals may be masked by the noisy climate system. One approach to overcoming this problem is investigating state-dependent predictability—how differences in prediction skill depend on the initial state of the system. We present a machine learning approach