We present a geological map of the different volcanic rocks present in the northeast Oman mountains. These volcanic rocks were erupted erupted at the seafloor, probably above a nascent subduction zone, and have since been transported by tectonic processes into their present, accessible position. The updated map allows us to understand the links between the different volcanic rock types and other geological features, including copper and chromite deposits, and will aid further study in the area.

Earthquake aftershocks display spatio-temporal correlations arising from their self-organized critical behavior. Stochastical models such as the Fiber Bundle (FBM) permit the use of an analog of the physical model that produces a statistical behavior with many similarities with real series. In this work, a new model based on FBM that includes geometrical faults systems is proposed. Our analysis focuses on aftershock statistics and as study case we modeled the Northridge sequence.

Image correlation techniques have provided new ways to analyze the distribution in space and time of deformation in analogue models of tectonics. Here we demonstrate how the correlation of successive time-lapse images of a deforming model allows calculating the finite displacements and finite strain tensor. We illustrate, using synthetic images, the ability of the algorithm to produce maps of the finite deformation.

In projects based on the Enhanced Geothermal System (EGS) technology the knowledge of the in-situ stress state is of central importance to predict the response of the rock mass to the different stimulation programs. We propose a characterization of the in-situ stress state from the analysis of Ultrasonic Borehole Imager (UBI) data acquired at different key moments of the reservoir. We discuss a significant stress rotation at depth and the absence of significant change in the stress magnitude.

Griffith (1921) assumed that energy used to create new surface area by breaking intact rock immediately becomes surface energy which is not available for further breakage. Our lab data disprove this assumption; we created much more new surface area, mostly on ultra-fine fragments, than the energy involved should allow. As technology allows ever smaller fragments to be measured, continued use of the Griffith assumption will lead to incorrect energy budgets for earthquakes and rock avalanches.

In this paper, we outline the key insights from decision making research about how, when faced with uncertainty, humans constrain decision through the use of heuristics (rules of thumb), making them vulnerable to systematic and sub-optimal decision biases. We also review existing strategies to debias decisions that have applicability in the geosciences, giving special attention to those strategies that make use of information technology and artificial intelligence.

Regularization is indispensable in regional gravity field modelling. In this paper, we propose two new approaches for the regularization parameter determination, which combine the L-curve method and variance component estimation (VCE). The performance of each method is studied for combining heterogeneous observations using spherical radial basis functions. The results show that our newly proposed methods are decent and stable for regularization parameter determination.

Knowing the velocity with which seismic waves travel through the top of the crust is important both for identifying anomalies, e.g. the presence of resources, but also for geophysical data evaluation. Traditionally this has been done by using empirical functions. Here, we use machine learning to derive better seismic velocity estimates for the crust below the oceans. In most cases this methods performs better than empirical averages.

Carbon capture and storage is a technology for the mitigation of industrial CO₂ emissions. Most subsurface storage capacity is in rocks for which there is relatively little information. A group of experts estimated the storage capacity of 7 units, producing a wide range of estimates for each unit due to a combination of using different published values for some variables and differences in their judgements of average values. Hence, there is significant uncertainty in such estimates.

Seismic reflection data allows us to infer subsurface structures such as horizon and fault surfaces. The interpretation of this indirect data source is inherently uncertainty and our work takes a first look at the scope of uncertainties involved in the interpretation of 3-D seismic data. We show how uncertainties of fault interpretations can be related to data quality and discuss the implications for the 3-D modeling of subsurface structures derived from 3-D seismic data.

Shear zones dominated by hydrated mantle rocks (serpentinites) occur in many tectonic settings around the world. To better understand the internal structure, composition and possible mechanical behaviour of these shear zones, we performed a detailed field, petrological and microanalytical study of the Livingstone Fault in New Zealand. We propose a conceptual model to account for the main physical and chemical processes that control deformation in large serpentinite shear zones.

The genesis of the continental crust above subduction zones remains controversial and massive production of granite in short period of time, also named flare-up events are more and more documented but poorly constrained. In the present manuscript we present a detailed geochemical study of samples collected in the Arequipa region (Peru), where a flare-up event is suspected. Using these data, we propose an elegant explanation for the converging geochemical signatures associated to this event.

We propose innovative parametric modeling allowing analysis of a very large number of fault-slip numerical simulations on 3-D discrete fault network. The approach allows for the first time producing failure envelopes of large rock volumes containing faults, using variations of geological conditions such as: remote stresses, cohesion, friction and fluid pressure. This tool helps to define the most conservative fault slip hazard case or to account for potential uncertainties in the input data.

Ancient evaporite sequences were deposited as interlayered rocksalt, other evaporites, and non-evaporite rocks that have enormous differences in strength. Whereas the ductile layers flow during deformation, strong layers are folded and/or torn apart, with the intrasalt deformation dependent on the mode and history of salt tectonics. This has important implications for accurately imaging and interpreting subsurface seismic data and for drilling wells through evaporite sequences.

We quantify the effects that 3-D fractures with realistic distributions of aperture have on seismic wave attenuation and velocity dispersion. Attenuation and dispersion are caused by fluid pressure diffusion between the fractures and the porous background. We show that (i) both an increase in the density of contact areas and a decrease in their correlation length reduce attenuation and (ii) a simple planar fracture can be used to emulate the seismic response of realistic fracture models.

To understand the fate of carbon in subducted oceanic sediments and crust, we studied carbonate phases in rocks from the Mariana subduction zone. These show that carbon is liberated from the downgoing plate at depths less than 20 km. Some of the carbon is subsequently trapped in minerals and likely subducts to greater depths, whereas fluids carry the other part back into the ocean. Our findings imply that shallow subduction zone processes may play an important role in the deep carbon cycle.

When carbon dioxide is introduced into the subsurface it will migrate upwards and can encounter faults, which, depending on their hydrogeological properties and composition, can form barriers or pathways for the migrating fluid. We analyse uncertainties associated with these properties in order to better understand the implications for the retention of CO₂ in the subsurface. We show that faults that form seals for other fluids may not be seals for CO₂, which has implications for storage sites.

Based on own and published age data, we can infer tectonic pulses along-strike the entire northern rim of the Central Alps between 12–4 million years. Although lithologic variations largely influence the local deformation pattern, the tectonic signal is remarkably consistent all the way from Lake Geneva to Salzburg. This might result from a deep-seated tectonic force and marks a change from dominantly vertical to large-scale horizontal tectonics in the late stage of Alpine orogeny.

We present a 2D model of the subsurface obtained by using seismic data acquired in the Alboran basin. We show the wave propagation velocity as physical property to characterize the studied area. We also explain the workflow followed to overcome the inherent problems of inverse methods used in a non-optimal dataset. The results validate the proposed workflow and the final image shows a number of geological meaningful structures providing a new insights in the formation/evolution of the basin.

A new code for anisotropic traveltime tomography is presented. We describe the equations governing the anisotropic ray propagation algorithm and the modified inversion solver. We study the sensitivity of two medium parametrizations and compare four inversion strategies on a canonical model. This code can provide better understanding of the Earth's subsurface in the rather common geological contexts in which seismic velocity displays a weak dependency on the polar angle of ray propagation.

The technique of X-ray computed tomography (CT) is widely used in multiple disciplines such as medicine, industry and earth sciences. However, quantitative analysis from the reconstructed images are subject to errors due to technical limitations and subsequent evaluation workflows. The paper addresses the uncertainties related to the estimation of porosity from these images and compares the results with laboratory measurements. Accurate porosity estimates are linked to sufficient resolution.

In this work we aim at interpreting the extended magnetic low visible at satellite-altitudes above central Europe performing a joint analysis of the magnetic field and total gradient intensity maps at low and high altitudes. Here we demonstrate that such magnetic anomaly is mainly a result of the contrast between two crustal platforms differing strongly in geological and magnetic properties. Synthetic model tests have been created to support our modeling.

An active CO₂-degassing site in the western Eger Rift/Czech Republic was investigated by using a 6.5 km long geophysical survey using a specific, large-scale geoelectrical setup, supported by shallow geoelectrical surveys and gravity measurements. The experiment reveals unusually low resistivities in the sediments and basement below the degassing area and provides a base for a custom geological model of the area for a future 400 m deep research drilling in this area.

It is in the subsurface where we we find many of our valuable and much needed resources (fossil and geothermal energy, rare earth minerals, water). Therefore, imaging and modelling of the subsurface is of paramount importance. We demonstrate a new and cost-effective approach for generating improved images of the subsurface, and show how the results can help us to map potential groundwater resources in large depths.

Our goal is to better understand the evolution of the Earth's outer shell in northeast Brazil. We analyse the propagation properties (anisotropy) of distant seismic waves in order to look for subsurface, large-scale deformation structures. Results show that structures visible at the surface can be traced down to ~ 100 km depth, that the imprint of the opening of the Atlantic Ocean can be detected along the coast, and that the continental interior is anomalous due to (perhaps) deep channel flows.

The formation of dolomite (Ca,Mg(CO3), an abundant mineral in Earth's geological record, is still incompletely understood. We studied dolomites embedded in a 100-m-thick succession of coastal alluvial clays of Triassic age in the Southern Alps. Observation by light microscopy and Sr-isotopes suggest that dolomites may have formed spontaneously from concentrated evaporating seawater, in coastal ephemeral lakes or tidal flats along the western margin of the Triassic Tethys sea.

In order to broaden our knowledge about the deep lithosphere using seismic methods, one shall target the development of leading-edge imaging workflows integrating different types of data. Here we exploit the complementary information carried by the seismic wavefields which are fundamentally different in terms of acquisition setting. We cast these information into the processing workflow and build the detailed model of the subduction zone which is subject to further geological interpretation.

Data acquisition costs mainly borne by expensive vibrator machines (i.e. deployment, operations and maintenance) can be regarded as the main impediment to wide application of seismic methods in mining industry. Here, we are showing that drill bit noise can be used to image the shallow subsurface when optimally acquired and processed. Drill bit imaging methods will then have many applications in small scale near surface projects such as those in mining exploration and geotechnical investigations.

Subduction-Transform Edge Propagator (STEP) faults are the locus of continual lithospheric tearing at the edges of subducted slabs, resulting in sharp changes in the lithospheric thickness and triggering lateral and/or near-vertical mantle flow. Here we study upper mantle rocks recovered from a STEP fault context by < 4 Ma alkali volcanism. We reconstruct how the microstructure developed during deformation and coupled melt-rock interaction, which are promoted by lithospheric tearing at depth.

Deep (> 40 km) seismic reflection surveys are acquired on land along crooked roads. Using the varying azimuth between source and receiver, the true 3-D orientation of crustal structures can be determined. Applying this method to a survey over the ancient Australian Yilgarn Craton reveals that most reflectors in the lower crust exhibit a systematic dip perpendicular to those in the overlying crust, consistent with lateral flow of a weak lower crust in the hotter early Earth 2.7 billion years ago.