Recent  

One of the main numerical methods to solve the mass, momentum and energy conservation equations in geodynamics is the Finite Element Method. Four main types of elements have been used in the past decades in hundreds of publications. We here for the first time compare results obtained with these four elements on a series of geodynamical benchmarks and applications and draw conclusions as to which are the best ones, and which are to be preferably avoided.

We studied the Gioia Sannitica active normal fault (GF) in southern Apennines (Italy). The GF is made of slowly-slipping faults, with a long slip history. Present activity has resulted in Late Quaternary fault scarps, and Holocene surface faulting. The maximum Late Quaternary throw rate is ~0.5 mm/yr. Activation of the 11.5 km-long GF can produce up to M 6.1 earthquakes. If activated together with the entire Southern Matese Fault system, the seismogenic potential would be M 6.8.

Past strong earthquakes can produce topographic deformations, often "memorized" in Quaternary sediments, which are typically studied by paleo-seismologists through trenching. Using a Ground Penetrating Radar (GPR), we unveiled possible buried Quaternary faulting in the Mt. Pollino region (southern Italy) in a total invasive way. We aim contributing to seismic hazard assessment of an area potentially prone to destructive events as well as promote our workflow in similar contexts around the world.

We present the first seismic noise variation levels during Covid-19 in Central America using ten seismometers. We study the impact of the seismic noise reduction on the detectability of earthquakes and in the felt reports. Our results show maximum values (~50 % decrease) in seismic stations near airports and densely cities. The decrease in seismic noise levels allowed to improve earthquake locations and reports. Our results show that it can be useful to verify the compliance of measures.

Raman spectroscopy of carbon-bearing rocks is often used to calculate peak temperatures and therefore burial history. However, strain is known to affect Raman spectral parameters. We investigate a series of deformed rocks that have been subjected to varying degrees of strain and find that there is a consistent change in some parameters in the most strained rocks, while other parameters are not affected by strain. We apply temperature calculations and find that strain affects them differently.

The Pollino region is a highly seismic area of Italy. Increasing the geological knowledge on areas like this contributes reducing risk and saving lives. We reconstruct the 3D model of the faults which generated the 2010–2014 seismicity integrating geological and seismological data. Appropriate relationships based on the dimensions of the activated faults, suggest that they did not fully discharge their seismic potential and could release further significant earthquakes in the near future.

One of the present-day challenges for geoscientists is tackling the Big Data revolution. An ever-growing amount of data needs to be processed and data are subjectively handled before using them to make inferences on the Earth’s interior. But imposing subjective decisions on the data might have strong influences on the final outputs. Here we present a totally novel and automatic application for screening the data and for defining data-volumes that are consistent with physical hypotheses.

Molasse deposits, deposited and deformed at the western alpine front during the Miocene (23 to 5.6 Ma), record the chronology of that deformation. We combine the first precise chronostratigraphy (precision of ~0.5 Ma) of the Miocene molasse, the reappraisal of the regional structure, and the analysis of growth deformation structures, in order to document three tectonic phases and the precise chronology of thrust westward propagation during the second one involving the Belledonne basal thrust.

Here we present new surface elevation constraints for the Middle Miocene Central Alps based on stable and clumped isotope geochemical analyses. Our reconstructed paleoelevation estimate is supported by isotope-enabled paleoclimate simulations and indicates that the Miocene Central Alps were characterized by a heterogeneous, and spatially transient topography with high elevations locally exceeding 4000 m.

This work analyses the density structure of the continental forearc in the northern segment of the 1960 Mw 9.6 Valdivia earthquake. Results show a segmentation of the continental wedge along and perpendicular to the margin. The extension of the less rigid basement units conforming the marine wedge and Coastal Cordillera domain could modify the process of stress loading during the interseismic periods. This analysis highlights the role of the overriding plate on the seismotectonic process

The present study shows evidence of hundreds-thousands of kilometers long, several kilometers thick fault (large cracks in the Earth's crust) systems extending from northwestern Russia to the northern Norwegian Barents Sea and the Svalbard Archipelago using seismic, magnetic, and gravimetric data. The study suggests that the crust in Svalbard and the Barents Sea was already attached to Norway and Russia at ca. 650–550 Ma, thus challenging existing models.

The lockdown imposed in Romania to prevent the spread of COVID-19 has significantly impacted the human activity across the country. By analyzing the ground vibrations recorded at seismic stations, we were able to monitor the changes in human activity before and during the lockdown. The reduced human activity during the lockdown has also provided a good opportunity for stations sited in noisy urban areas to record earthquake signals that would not have been recorded under normal conditions.

In this contribution, we address the current gap in undergraduate geoscience education on uncertainty. We present a framework for teaching students to characterize, assess, and convey uncertainty that is suitable for both traditional in-person and virtual field experiences. The framework provides students relief from the distress of "not knowing" by providing a language to communicate uncertainty, and affirms their scientific growth by making reductions in uncertainty more conspicuous.

We use numerical simulations and laboratory experiments on rock samples to investigate how stress conditions influence the geometry and roughness of fracture surfaces. The roughness of the surfaces was analysed in terms of absolute roughness and scaling properties. The results show that the surfaces are self-affine, but with different scaling properties between the numerical models and the real rock samples. Results suggest that stress conditions have little influence on the surface roughness.

As continental plates collide, mountain belts grow. This study investigated the provenance of rocks from the northwestern segment of the Zagros mountain belt to unravel the convergence history of the Arabian and Eurasian plates. Provenance data synthesis and field relationships suggest that Zagros mountains developed as a result of the oceanic crust emplacement on the Arabian continental plate, followed by the Arabia-Eurasia collision, and later uplift of the broader region.

The 2 June 1994 Java tsunami earthquake ruptured in a seismically quiet subduction zone and generated a larger-than-expected tsunami. Here, we re-process a seismic line across the rupture area. We show that a subducting seamount is located up-dip of the mainshock in a region that did not rupture during the earthquake. Seamount subduction modulates the topography of the marine forearc and controls the seismic slip propagation during the earthquake by deflecting the rupture around the seamount.

New images from the multi-national AlpArray experiment illuminate the Alps from below. They indicate thick European mantle descending beneath the Alps and forming blobs that are mostly detached from the Alps above. In contrast, the Adriatic mantle in the Alps is much thinner. This difference helps explain the rugged mountains and the abundance of subducted and exhumed units in the core of the Alps. The blobs are stretched remnants of old ocean and its margins that reach down to at least 410 km.

Sediments accumulated in accretionary prims are deformed by the compression imposed by plate subduction. Here we show that deformation of the sediments transforms some minerals in them. We suggest that these mineral transformations are due to the proliferation of microorganisms boosted by deformation. Deformation-enhanced microbial proliferation may change our view of sedimentary and tectonic processes in subduction zones.

We analyze folded multilayer sequences in the Ocnele Mari salt mine (Romania) to gain an insight into the long-term rheological behavior of rocksalt. Our results indicate a great role of even a small amount of impurities in the rocksalt on its effective mechanical behaviour. We demonstrate how the development of folds that develop at various scales can be used to constraining the viscosity ratio in the deformed multilayer sequence.

The Ligurian Sea opened ~30–15 Ma during the SE migration of the Calabrian subduction zone. Using ambient seismic noise from stations on land and at the ocean bottom, we calculated a 3D shear-velocity model of the Ligurian Basin. We find a shallow crust-mantle transition at the southwestern basin centre that deepens towards the Liguro-Provencal coast. We see no evidence for an Alpine slab beneath the basin. However, a separation of SW and NE basin appears to prolong the onshore Alpine front.

The Alpine mountain belt was formed by the collision of the Eurasian and African plates in the geological past, during which parts of the colliding plates sank into the Earth's mantle. Using seismological data from distant earthquakes recorded by the AlpArray Seismic Network, we have derived an image of the current location of these subducted parts in the Earth's mantle. Their quantity and spatial distribution is key information needed to understand how the Alpine orogen was formed.

The seismicity of Fogo and Brava, Cape Verde, is dominated by volcano-tectonic earthquakes in the area of Brava and volcanic seismic signals, such as hybrid events, on Fogo. We locate these events using a multi-array analysis, which allows the localization of seismic events occurring outside the network and of volcanic signals lacking clear phases. We observe exceptionally high apparent velocities for the hybrid events, located on Fogo. These velocities are likely caused by a complex ray path.

We have performed a detailed study of the rocks surrounding a major Zn-Pb-Cu ore deposit in southwest Spain in order to characterize the behavior of chemical elements in the influence area of the hydrothermal system that produced the deposit. Based on this information we propose new ways of detecting the nearby presence of ore deposits of this kind during exploration, thus improving our ability to detect new resources and contributing to securing the future supply of metals for our society.

The long-lived Schio-Vicenza Fault System is a major shear zone cross-cutting the foreland and the thrust belt of the Eastern Southern Alps. We review 150 years of scientific works, and explain its activity and kinematics, characterised by sinistral and dextral transcurrent motion along its southern and northern sections, respectively, by a geodynamic model that has the Adria indenter as the main actor, and coherently reconciles the available geological and geophysical evidence collected so far.

An experimentally-deformed sample of Opalinus Clay, considered as host rock for nuclear waste in Switzerland, was studied by electron microscopy to image deformation microstructures. Observations showed that deformation localized by forming micrometre-thick fractures. Deformation zones show dilatant micro-cracking, granular flow and bending grains, and pore collapse. Our deformation model with three different stages of damage accumulation illustrates the mechanics in a compressed OPA sample.

Rock fractures are organized as networks with spatially varying arrangements. Owing to networks' influence on bulk rock behavior, it is important to quantify network spatial variation. We utilize an approach where fracture networks are treated as spatial graphs. By combining graph similarity measures with clustering techniques, spatial clusters within large-scale fracture networks are identified and organized hierarchically. The method is validated on a dataset with nearly 300,000 fractures.

In the first part of this article, we present a new methodology that we have developed to model the deformation and the microstructural evolutions of olivine rocks, which compose the main part of the Earth upper mantle. In a second part, using this methodology we show that microstructural features such as small grain sizes and preferential grain orientations can localize strain at the same intensity and can act together to produce an even stronger strain localization.

We imaged some structures related to a major fault plane which have not been illuminated by a previously conducted 3D active seismic survey due to their large dip angles. The imaging procedure is conducted by using microearthquakes as seismic sources.

The insights of this study will help to better understand how to identify basement linear structures and how these lineaments could be related to surface lineaments or geology in the context of the Central Gawler Craton, and to provide better targeting of surface areas to detect subsurface mineral systems in this region.