The paper describes microstructures in granitic rocks located 50 m away from the Nojima fault in Japan. Although macroscopically undeformed, the sample displays evidence for intense dynamic damage at the microscopic scale. Elastic strain and high residual stresses stored in quartz grains suggest that they were produced by propagating rupture fronts associated with M6 to M7 earthquakes and contributed to the widening of the damaged fault zone along the Nojima fault during the Paleocene. Hide

By analyzing frequency constituents of declination secular variation at inter-decadal and sub-centennial timescales from geomagnetic observatories with data longer than 1 century and several historical data sets, we suggest that the geomagnetic jerk concept should be considered as a more general notion, namely the evolution of the secular variation as a result of the superposition of two (or more) constituents describing the effects of processes in the Earth’s core at two (or more) timescales. Hide

We present new data on the orientation of fractures, their fill, and their density around the Alpine Fault, a plate boundary fault on the South Island of New Zealand. Fractures < 160 m of the fault are filled and show a range of orientations, whilst fractures at greater distances (< 500 m) are open and parallel to the rock's mechanical weakness. We interpret the latter fracture set to reflect near-surface processes, whilst the latter are potentially linked to deep-seated Alpine Fault seismicity. Hide

We computed a global map of crustal thickness covering the entire Antarctic continent from GOCE satellite gravimetric data. We compare our result to seismological models: a fairly good agreement is shown. However, better resolution is obtained using the gravity observations than using only seismological ones. This research will help us to understand the geology of Antarctica. Hide

We prove here that macroscopic and microscopic studies of emitted pyroclastic and effusive products provide valuable information to track and understand small explosive eruptions for hazard and risk assessment. This is especially true for Piton de La Fournaise, La Réunion, whose activity has recently been characterized by effusive and mild explosive activity in highly visited areas. We confirm that petrological monitoring is essential to forecast changes in the magmatic system. Hide

We use seismic reflection data and quantitative fault analyses to examine how a sub-crustal lineament, the Sorgenfrei–Tornquist Zone, is expressed within upper-crustal rift systems off the shore of southern Norway. We document repeated reactivation of upper-crustal faults, displaying both sinistral and dextral oblique activity, which we link to underlying lineament and regional tectonics. We show how sub-crustal lineaments influence rift evolution and offer insights into past tectonic events. Hide

MCUE is a method that produces probabilistic 3-D geological models by sampling from distributions that represent the uncertainty of the initial input dataset. This process generates numerous plausible datasets used to produce a range of statistically plausible 3-D models which are combined into a single probabilistic model. In this paper, improvements to distribution selection and parameterization for input uncertainty are proposed. Hide

The goal of this work is to study large cracks in the Earth's crust called faults near the coast of northern Norway in the SW Barents Sea. We interpreted seismic data (equivalent to X-ray diagram of the Earth) that showed the presence of a large fault near the coast of Norway, which contributed to building the mountain chain observed in Norway and later helped open the North Atlantic Ocean, separating Greenland from Norway. Hide

Since 2002, the GRACE mission provides estimates of the Earth's time-variable gravity field, from which one can derive ocean mass variability. Now that the GRACE mission has come to an end, it is especially important to find alternative ways for deriving ocean mass changes. For the first time, we use kinematic orbits of Swarm for computing ocean mass time series. We compute monthly solutions, but also show an alternative way of directly estimating time-variable spherical harmonic coefficients. Hide

Central and Eastern Anatolia (present-day Turkey) accommodated Africa–Eurasia convergence in Cenozoic times. As a result, the region underwent distributed deformation and rotation. We provide a paleomagnetic dataset from sedimentary basins and assess the timing and amount of rotations. The obtained rotation patterns together with known fault zones suggest that south-central Turkey represents a coherently counterclockwise-rotating domain. Hide

A nonlinear viscoplastic rheology is implemented and benchmarked in the ASPECT software, allowing for the modeling of lithospheric deformation. We showcase the new functionality with a four-dimensional model of thermomechanically coupled subduction. Hide

We monitored the bromine monoxide-to-sulfur dioxide molar ratio in the effusive gas plume of Cotopaxi volcano in order to gain insight into the geological processes which control the pressure regime of the volcanic system. We observed a conspicuous periodic pattern with a periodicity of about 2 weeks, which significantly correlates with the Earth tidal forcing. Our results support a possible Earth tidal impact on volcanic activity, in particular for the Cotopaxi eruption 2015. Hide

The gneiss conductivities markedly increase with total alkali and calcium ion content. The influence of pressure on gneiss conductivity is weaker than temperature, although conductivity still increases with pressure. The results cannot be used to interpret the HC anomalies in the Dabie–Sulu UHPM belt. However, the conductivity–depth profiles for gneiss may provide an important constraint on the interpretation of field magnetotelluric conductivity results in the regional metamorphic belt. Hide

Graphite crystallinity “irreversibly” increases with temperature and it has been calibrated as a thermometer recording peak temperatures experienced by a rock. To examine the possibility of mechanical modifications of graphite structure and the impacts on graphite thermometry we performed deformation experiments. Raman spectroscopy demonstrates a reduction in crystallinity due to mechanical reworking in the brittle field. This finding clearly compromises the validity of the graphite thermometry. Hide

Continental high-pressure terranes in orogens offer insight into deep recycling and transformation processes that occur in subduction zones. These remain poorly understood, and currently debated ideas need testing. We document complex garnet zoning in eclogitic mica schists from the Sesia Zone (western Italian Alps). These retain evidence of two orogenic cycles and provide detailed insight into resorption, growth, and diffusion processes induced by fluid pulses under high-pressure conditions. Hide

Subducted continental terranes commonly comprise an assembly of subunits that reflect the different tectono-metamorphic histories they experienced in the subduction zone. Our challenge is to unravel how, when, and in which part of the subduction zone these subunits were juxtaposed. Our study documents when and in what conditions re-equilibration took place. Results constrain the main stages of mineral growth and deformation, associated with fluid influx that occurred in the subduction channel. Hide