Fault Plane Research Articles

Thermal transport recovery in irradiated SiC mediated by nano-layered stacking faults

We investigate phonon thermal transport and resistance to ion irradiation in nanostructured 3C-SiC using molecular dynamics (MD) simulations. Two-dimensional planar defects in the form of stacking faults (SFs) spaced within nanometer-scale vicinity from each other promote healing of both: radiation-induced point defects (PDs) and thermal conductivity (k) under 10 keV Si ion irradiation number of displacements per atoms (DPA= 0.0016 – 0.034). With the rise of DPA below the onset of amorphization, the decay in k due to PDs and SFs is found to be less rapid than that due to the presence of only PDs. Observed relative recovery of heat conductivity is due to enhanced recombination of Frenkel pair PDs spatially confined between neighboring SFs, as confirmed by collision cascade MD simulations. Calculations from the Boltzmann transport equation combined with the Klemens model are consistent with findings from MD simulations. The interplay between enhanced PD recombination and thermal transport recovery is observed for different types of SFs. Obtained results pave the way to guide the design of nano-engineered nuclear ceramics with simultaneously enhanced radiation tolerance and heat conductive properties.

Molecular dynamics simulations of interaction between a super edge dislocation and interstitial dislocation loops in irradiated [formula omitted]-Ni3Al

The study employed MD simulations to investigate the interactions between a 〈11¯0〉 super-edge dislocation, consisting of the four Shockley partials, and interstitial dislocation loops (IDLs) in irradiated L12-Ni3Al. Accounting for symmetry breakage in the L12 lattice, the superlattice planar faults with four distinct fault vectors have been considered for different IDL configurations. The detailed dislocation reactions and structural evolution events were identified as the four partials interacted with various IDL configurations. The slipping characteristics of Shockley partials within the IDLs and the resultant shearing and looping mechanisms were also clarified, revealing distinct energetic transition states determined by the fault vectors after the Shockley partials sweeping the IDL. Furthermore, significant variations in critical resolved shear stress (CRSS) required for the super-edge dislocation to move past the IDL were observed, attributed to various sizes and faulted vectors of enclosed superlattice planar faults in the IDLs. The current study extends the existing dislocation-IDL interaction theory from pristine FCC to L12 lattice, advances the understanding of irradiation hardening effects in L12-Ni3Al, and suggests potential applicability to other L12 systems.

Insights into Chemical and Structural Order at Planar Defects in Pb2MgWO6 Using Multislice Electron Ptychography.

Switchable order parameters in ferroic materials are essential for functional electronic devices, yet disruptions of the ordering can take the form of planar boundaries or defects that exhibit distinct properties from the bulk, such as electrical (polar) or magnetic (spin) response. Characterizing the structure of these boundaries is challenging due to their confined size and three-dimensional (3D) nature. Here, a chemical antiphase boundary in the highly ordered double perovskite Pb2MgWO6 is investigated using multislice electron ptychography. The boundary is revealed to be inclined along the electron beam direction with a finite width of chemical intermixing. Additionally, regions at and near the boundary exhibit antiferroelectric-like displacements, contrasting with the predominantly paraelectric matrix. Spatial statistics and density functional theory (DFT) calculations further indicate that despite their higher energy, chemical antiphase boundaries (APBs) form due to kinetic constraints during growth, with extended antiferroelectric-like distortions induced by the chemically frustrated environment in the proximity of the boundary. The three-dimensional imaging reveals the interplay between local chemistry and the polar environment, elucidating the role of antiphase boundaries and their associated confined structural distortions and offering opportunities for engineering ferroic thin films.

Advances on Defect Engineering of Niobium Pentoxide for Electrochemical Energy Storage.

The reasonable design of advanced anode materials for electrochemical energy storage (EES) devices is crucial in expediting the progress of renewable energy technologies. Nb2O5 has attracted increasing research attention as an anode candidate. Defect engineering is regarded as a feasible approach to modulate the local atomic configurations within Nb2O5. Therefore, introducing defects into Nb2O5 is considered to be a promising way to enhance electrochemical performance. However, there is no systematic review on the defect engineering of Nb2O5 for the energy storage process. This review systematically analyzes first the crystal structures and energy storage mechanisms of Nb2O5. Subsequently, a systematical summary of the latest advances in defect engineering of Nb2O5 for EES devices is presented, mainly focusing on vacancy modulation, ion doping, planar defects, introducing porosity, and amorphization. Of particular note is the effects of defect engineering on Nb2O5: improving electronic conductivity, accelerating ion diffusion, maintaining structural stability, increasing active storage sites. The review further summarizes diverse methodologies for inducing defects and the commonly used techniques for the defect characterization within Nb2O5. In conclusion, the article proposes current challenges and outlines future development prospects for defect engineering in Nb2O5 to achieve high-performance EES devices with both high energy and power densities.

Preliminary Test of Source Parameters of Mwp6 Italian Earthquakes: Revisiting Kinematic Function Method

Macroseismic intensity data are the only source of information for historical earthquakes; it is therefore necessary to devise methods that allow us to retrieve as many source parameters as possible on the basis of these data. We present the inversion of macroseismic data as a first validation of an improved version of the kinematic function, KF. Following the previous results of some earthquakes on Italian territory and several validations by Californian events provided with instrumental solutions, we have now simplified the KF by reducing some degrees of freedom of the parameters and rearranging the code for parallel calculation. This approach will allow for a more extensive application of the KF technique. We present the inversion of the macroseismic intensity pattern of the Mwp6 earthquake of 27 March 1928 (8:32 GMT), which occurred in Northeastern Italy (Carnia), and we retrieved source parameters that are compatible with the solutions of other authors who independently treat instrumental data. The 1928 event is located a few tens of kilometers west of the more destructive Mw6.5 of 6 May 1976 and northeast of the subsequent earthquake Mwp6.1 of 18 October 1936. The inversion was performed as a blind test, without prior knowledge for fault plane solutions and tectonic information; it resulted in a minimum variance model with a strike of 62°, a dip of 10°, and a rake of 101°. This solution is not consistent with the entire tectonic framework of the eastern Southalpine chain, but it is in agreement with the But-Chiarsò line. This result encourages us to test further improvements to the KF method and to treat other cases from the Italian macroseismic catalog.

Recent advances in synthesis and application of Magnéli phase titanium oxides for energy storage and environmental remediation.

High-temperature reduction of TiO2 causes the gradual formation of structural defects, leading to oxygen vacancy planar defects and giving rise to Magnéli phases, which are substoichiometric titanium oxides that follow the formula Ti n O2n-1, with 4 ≤ n ≤ 9. A high concentration of defects provides several possible configurations for Ti4+ and Ti3+ within the crystal, with the variation in charge ordered states changing the electronic structure of the material. The changes in crystal and electronic structures of Magnéli phases introduce unique properties absent in TiO2, facilitating their diverse applications. Their exceptional electrical conductivity, stability in harsh chemical environments and capability to generate hydroxyl radicals make them highly valuable in electrochemical applications. Additionally, their high specific capacity and corrosion resistance make them ideal for energy storage facilities. These properties, combined with excellent solar light absorption, have led to their widespread use in electrochemical, photochemical, photothermal, catalytic and energy storage applications. To provide a complete overview of the formation, properties, and environmental- and energy-related applications of Magnéli phase titanium suboxides, this review initially highlights the crystal structure and the physical, thermoelectrical and optical properties of these materials. The conventional and novel strategies developed to synthesise these materials are then discussed, along with potential approaches to overcome challenges associated with current issues and future low-energy fabrication methods. Finally, we provide a comprehensive overview of their applications across various fields, including environmental remediation, energy storage, and thermoelectric and optoelectronic technologies. We also discuss promising new directions for the use of Magnéli phase titanium suboxides and solutions to challenges in energy and environment-related applications, and provide guidance on how these materials can be developed and utilised to meet diverse research application needs. By making use of control measures to mitigate the potential hazards associated with their nanoparticles, Magnéli phases can be considered as versatile materials with potential for next generation energy needs.

Fluid flow in crustal fault zones with varying lengthwise thickness: application to the Margeride fault zone (French Massif Central)

Crustal fault zones, holding promise as potential geothermal reservoirs, remain largely untapped and unexplored. Located in the southern Massif Central, France, the Margeride fault zone (MFZ) varies in thickness (lateral extension perpendicular to the fault plane) from 100 m to over 2500 m. Reactivated several times under different stress regimes since the Variscan orogeny, this zone is characterized by an intense alteration and fracturing. As a result, the multiple reactivation of the fault zone has maintained permeability, leading to favourable conditions for fluid circulation. Structural measurements and geological cross sections were used to precisely constrain thickness and geometry of the fault zone. North of the MFZ, the Coren thermal spring indicates reservoir temperatures of about 200–250 °C, hinting at the possible existence of a temperature anomaly. To investigate this geothermal potential, 3D numerical models simulating fluid circulation within a fault zone were conducted. Various configurations were explored, altering fault zone thickness and permeability for two key geometries. The first geometry, which manipulated the width of the fault zone along its length, demonstrated a direct correlation between fault zone thickness and amplitude of thermal anomaly. Thinner faults (< 500 m) exhibited multiple weak positive thermal anomalies, while thicker faults (> 500 m) tended to develop a single, substantial positive thermal anomaly. In the second examined geometry, where fault zone thickness increased longitudinally, a consistent positive temperature anomaly emerged at the thickest section of the fault zone. Depending on the permeability value, an additional anomaly may develop but will migrate laterally towards the thinnest part of the fault zone. This multi-disciplinary approach, combining numerical modelling and field measurements, presents a predictive methodology applicable to geothermal exploration in analogous basement domains. In our case, it has shown that the northern end of the Margeride fault zone could represent an area that needs to be explored further to assert its high geothermal potential. Our numerical models will increase understanding of how fault width and geometry impact the geothermal potential of the Margeride fault zone and similar areas in crystalline basement.

Experimental Study on Tunnel Failure Mechanism and the Effect of Combined Anti-Dislocation Measures Under Fault Dislocation

Taking the tunnels crossing active faults in China’s Sichuan–Tibet Railway as the research background, experimental studies were conducted using a custom-developed split model box. The research focused on the cracking characteristics of the surrounding rock surface under the action of strike-slip faults, the progressive failure process of the tunnel model, and the mechanical response of the tunnel lining. In-depth analyses were performed on the tunnel damage mechanism under strike-slip fault action and the mitigation effects of combined anti-dislocation measures. The results indicate the following: Damage to the upper surface of the surrounding rock primarily occurs within the fault fracture zone. The split model box enables the graded transfer of fault displacement within this zone, improving the boundary conditions for the model test. Under a 50 mm fault displacement, the continuous tunnel experiences severe damage, leading to a complete loss of function. The damage is mainly characterized by circumferential shear and is concentrated within the fault fracture zone. The zone 20 cm to 30 cm on both sides of the fault plane is the primary area influenced by tunnel forces. The force distribution on the left and right sidewalls of the lining exhibits an anti-symmetric pattern across the fault plane. The left side wall is extruded by surrounding rock in the moving block, while the right side wall experiences extrusion from the surrounding rock in the fracture zone, and there is a phenomenon of dehollowing and loosening of the surrounding rock on both sides of the fault plane; the combination of anti-dislocation measures significantly enhances the tunnel’s stress state, reducing peak axial strain by 93% compared to a continuous tunnel. Furthermore, the extent and severity of tunnel damage are greatly diminished. The primary cause of lining segment damage is circumferential stress, with the main damage characterized by tensile cracking on both the inner and outer surfaces of the lining along the tunnel’s axial direction.

New Insights on the Seismic Activity of Ostuni (Apulia Region, Southern Italy) Offshore

On 23 March 2018, an event of magnitude ML 3.9 occurred about 10 km from the town of Ostuni, in the Adriatic offshore. It was the most energetic earthquake in South–Central Apulia ever recorded instrumentally. On 13 February 2019, in the same area, a second ML 3.3 event was recorded. The analysis of the 2018 event shows that the ambiguity of the solution of the fault plane reported by INGV (Istituto Nazionale di Geofisica e Vulcanologia) on the Italian National Earthquake Centre website can be solved considering existing seismic profiles, exploration well logs and the Quaternary activity of faults in the epicentral area. A seismogenic source was identified in the rupture of a small portion of a 40 km length structure with strike NW-SE, dipping at a high angle toward the south. In this work, we have relocated the recent earthquakes by using the seismic stations managed by the University of Bari (UniBa), one of which is quite close to the event’s epicenter (about 20 km), together with data coming from the RSN (Rete Sismica Nazionale). Furthermore, we have determined the focal mechanism of some events, with implications on stress field of the area. Our results show right-lateral transtensional kinematics of the seismogenic faults along approximately E-W striking planes, with a tension, T, with a trend of about 60° (NE-SW direction) and a plunge of 20°. Finally, we have tried to correlate the location of the four best constrained earthquakes with their seismogenic structures.

Intraplate seismicity in southwestern Norway: Enhanced catalogue highlights diffusive earthquake occurrence linked to inherited weakness zones

Summary Intraplate earthquakes in stable continental regions exhibit diverse characteristics in terms of timing, spatial distribution, and magnitude. They are often unexpected, and their underlying physical mechanisms are not well understood. This complexity is particularly apparent in Norway, where seismicity is mostly localised on the continental margin and coastal areas. Various studies have attempted to explain the causes of seismicity in Norway by invoking different sources of stress, ranging from regional stress due to ridge push to local effects such as topography or deglaciation. In this study, we revisit these questions by investigating the distribution of seismicity in southwestern Norway using an enhanced earthquake catalogue. To achieve this, we revised the Norwegian National Seismic Network seismic catalogue from 2000 to 2023 and built a new catalogue using machine-learning-based techniques on data from a temporary seismic deployment in the region. Thanks to the increased station density during this deployment, we were also able to calculate new fault plane solutions that consistently showed a WNW-ESE direction for the most compressive axis. Furthermore, we demonstrate that seismicity in southwestern Norway, while diffuse, tends to be localised around the major crustal shear zones of the region, such as the Bergen Arc Shear Zone and the Hardangerfjord Shear Zone.

Multielement-Doped Tungstic Acids via Submerged Photosynthesis for Enhanced All-Solar Photoelectrochemical Responses.

Bifunctional electrode materials that can convert solar energy into electricity and store chemical energy are a functional strategy for resolving the instability of solar energy. However, most commonly used transition metal oxide semiconductor materials lack broadband wavelength absorption responses, resulting in incomplete solar energy utilization. Herein, multielement-doped MoxW1-xO3·0.33H2O nanoparticles synthesized via the one-pot submerged photosynthesis of crystallite (SPsC) method are proposed to improve the full-spectrum solar responses of tungstic acids. The solar absorption efficiency of MoxW1-xO3·0.33H2O increases from 54 to 81% after Cu, Fe, and Mn doping. This increase in the solar absorption efficiency of MoxW1-xO3·0.33H2O improves its photogenerated capacitance by 18.7 times, which is attributed to the increase in the number of photogenerated charge carriers and planar defect structures produced via multielement doping. Moreover, ab initio calculations theoretically explain the relation between the elemental doping and corresponding absorption wavelengths of MoxW1-xO3·0.33H2O, providing instructions for tuning the light absorption wavelength of transition metal oxide semiconductor materials. Multielement doping achieved via the low-cost SPsC method enhances the photocarrier response to increase the photogenerated capacitance. This response demonstrates the importance of full-spectrum solar absorption, offering a prominent strategy for designing solar energy storage materials in the future.

Temporal and spatial variability of S-wave and coda attenuation in the Central Apennines, Italy

The central Apennines are notoriously subject to important seismic sequences, such as the 2009 and 2016–2017, L’Aquila, Amatrice-Visso-Norcia (AVN) sequences, respectively. Here, we examine the temporal and spatial variation of the S-wave attenuation in Central Italy over a period from 2011 to 2017, including the AVN sequence. First, we computed the S-wave attenuation (Qβ) as a function of frequency Q(f) using the coda normalization method. Then, to visualize the spatial variation of the attenuation over time, we calculated the attenuation of coda waves using a novel 2D kernel-based function over the study area. Our results showed a 13% variation in S-wave attenuation between the pre-sequence (2011–2016) and the sequence phase, with a significant 37% decrease in Q (increase in attenuation) detected during the Visso period. Spatially, a high attenuation anomaly aligns with the Monti Sibillini thrust formation, while in time, we observed a northward migration of this high attenuation during the Norcia phase. Temporal variation in the crustal S-wave attenuation and its frequency dependence may be linked to fluid movement and fracturing developed during the AVN sequence. Coda-Q mapping confirmed an increase in attenuation during the sequence within the fault plane zones. Additionally, the broader area of interest reveals a northward extension of high attenuation, following the NS direction of the Monti Sibillini thrust.

Probabilistic estimation of rheological properties in subduction zones using sequences of earthquakes and aseismic slip

Abstract Constraining the effective rheology of major faults contributes to improving our understanding of the physics of plate boundary deformation. Geodetic observations over the earthquake cycle are often used to estimate key rheological parameters, assuming specific laboratory-informed classes of viscous or frictional rheological models. However, differentiating between various rheological model classes using only observations of a single earthquake (coseismic and postseismic deformation) is difficult—especially in the presence of coarse spatiotemporal sampling, inherent observational noise, and non-uniqueness of the inverted properties. In this study, we present a framework to estimate key rheological parameters of a subduction zone plate interface using simulations of sequences of earthquakes and aseismic slip, constrained by pre- and postseismic surface displacement timeseries. Our simplified forward model consists of a two-dimensional subduction zone, represented by a discretized planar fault or narrow shear zone, divided into a locked, shallow region (“asperity”) experiencing periodically imposed coseismic events, and a stress-driven creeping section governed by power-law viscoelasticity or rate-dependent friction. Our inverse model fits the rheological parameters of the interface to surface displacement timeseries in a Bayesian probabilistic way. We validate that our proposed framework can successfully recover depth-dependent profiles of effective viscosity using a synthetic dataset of pre- and postseismic observations. Our first set of numerical experiments show that our framework is only mildly sensitive to uncertainties in the rupture history or assumed coseismic slip, making it robust enough to be applied to real observations of subduction zones. Our second set of tests considers the similarities of surface displacement timeseries between synthetic models that model the plate interface either as a shear zone described by power-law viscosity, or a surface described by rate-dependent friction. Here, we find that the ability to fit surface observations using functional or mechanical models assuming frictional behavior does not constitute sufficient evidence to actually infer frictional behavior at depth, as the surface expressions are virtually indistinguishable from deformation generated from models with depth-variable power-law viscous behavior. Based on our numerical experiments, we conclude that studies that aim to infer the mechanical behavior and rheological properties at depth in subduction zones should consider the surface expression from time periods representative of the entire seismic cycle. Graphical Abstract

Step characteristics and formation mechanism of strike slip faults in Wuerhe asphalt vein, Junggar Basin

In order to define the geometric characteristics, formation mechanism and fault wall movement direction of steps about mini-extensional shear strike-slip fault zone in Wuerhe asphalt vein. Field outcrop observation, 3D seismic data interpretation, fracture formation time and stress mechanism analysis were carried out. There is no friction in the vein section and the initial fracture shape is maintained. Not only negative steps but also steps is developed, and even steps and negative steps coexist in a cross section. The step is the microtension rupture surface associated with the strike-slip fault plane, which does not have the pointing significance of the fault wall relative movement. The outcrop features are typical, which overturns the consensus of domestic and foreign scholars based on the structural physics simulation experiments that the small steepness generated at the early stage of normal fault, reverse fault and strike-slip fault sections are all negative steps.

Impact of grain boundaries on the electronic properties and Schottky barrier height in MoS2@Au heterojunctions.

Using density functional theory (DFT) calculations we thoroughly explored the influence of grain boundaries (GBs) in monolayer MoS2 composed of S-polar (S5|7), Mo-polar (Mo5|7), and (4|8) edge dislocation, as well as an edge dislocation-double S vacancy complex (S4|6), and a dislocation-double S interstitial complex (S6|8), respectively, on the electronic properties of MoS2 and the Schottky barrier height (SBH) in MoS2@Au heterojunctions. Our findings demonstrate that GBs formed by edge dislocations can significantly reduce the SBH in defect-free MoS2, with the strongest effect for zigzag (4|8) GBs (-20% reduction) and the weakest for armchair (5|7) GBs (-10% reduction). In addition, a larger tilt angle in the GBs leads to a more pronounced decrease in the SBH, suggesting that the modulation of SBH in the MoS2@Au heterostructure and analogous systems can be accomplished by GB engineering. Our findings also suggest that planar defects with high mobility in MoS2 may contribute to the memory switching effect observed in MoS2-based memtransistors and the reduction caused by the presence of planar defects can partially contribute to the discrepancy observed between experimental measurements and theoretical SBH predictions at the MoS2@Au heterojunction.

Kinematic source rupture on listric faults for the 2024 Noto Peninsula, Japan, earthquake (Mw 7.5) estimated from near-field strong-motion waveforms

On January 1, 2024, an Mw 7.5 reverse-fault earthquake occurred along the submarine active faults just offshore of the Noto Peninsula in central Japan. This earthquake is one of the largest inland crustal earthquakes that ever recorded in Japan. We performed inversions of near-field strong-motion waveforms (0.05–0.25 Hz) to investigate the kinematic rupture process of this earthquake. For the inversions, we assumed listric fault planes, where the dip angles are steeper near the seafloor and become gentler with increased depth, based on the location of the submarine fault offsets, the structure at shallow depths revealed by seismic reflection surveys, and the relocated aftershock distribution at deep depths. To constrain our kinematic source model, we also utilized geodetic information published by the Geospatial Information Authority of Japan. We identified that the rupture process had three phases. The first phase was the initial rupture with a small slip of ~ 2 m around the rupture initiation area. After several seconds, the second and third phases, which were the main ruptures, propagated in the southwest and northeast directions, respectively. During the second and third phases, five large slip areas with average slips of 5–6 m significantly contributed to the strong-motion waveforms. By forward-simulating the geodetic data, we found that the rupture at shallow depths included an oblique component close to a right-lateral component and that, in the eastern part of the source region, the rupture transferred from a southeastward-dipping fault to a northwestward-dipping fault. The listric fault with high dip angles at shallow depths is better than a planar fault with a single dip angle for accurately modeling the fault slip near the surface and the coseismic displacement close to the fault trace during the reverse-fault earthquake.Graphical abstract

Role of Intraplate Strike-Slip Earthquakes in Accommodating Convergence Across the Eastern Himalayan Plate Boundary System

Abstract North-East India, at the eastern extremity of the Himalaya, is one of the most rapidly deforming intraplate regions. The tectonics of this region is shaped by oblique convergence between two nearly perpendicular plate boundaries of the Eastern Himalaya and the Indo-Burman convergence zone. This region of distributed deformation is associated with intraplate strike-slip and oblique-slip earthquakes. We model the source mechanisms of six recent moderate-to-strong intraplate earthquakes (5.0≤ Mw ≤6.7) using teleseismic P- and SH-waveform inversion and use source directivity and rupture back-projection, for the largest event, to isolate the fault plane. We combine these mechanisms with previous earthquake source studies, GPS-geodetic-velocity vectors, and GPS-derived strain-rate field, to build a kinematic model. Majority of the earthquakes have strike-slip to oblique-slip (thrust) motion and originate in the middle-to-lower crust. These reveal that the entire NE-Indian crust is seismogenic. The oblique-thrust earthquakes occur due to high in-plane compressive stresses in the flexed Indian Plate. The region north of the Dawki Fault, in the vicinity of the Kopili and Dhubri-Chungthang Fault Zones, deforms through dextral strike-slip faulting and anticlockwise rotation of blocks along NW-SE trending transverse structures. The transitional crust of the Bengal Basin has several NE-SW trending paleo-rifts which are reactivated as sinistral strike-slip faults and the intervening blocks undergo clockwise rotation. The oblique convergence between the Indian and Eurasian Plates is partitioned into dextral and sinistral strike-slip motions across NE-India. The GPS velocity vectors and the strain-rate field indicate that the region north of the Dawki Fault has strong coupling between the surface deformation and the earthquake faulting. However, in the region south of the Dawki Fault, the coupling is weaker. The strike-slip earthquakes beneath Indo-Burma probably occur due to a complex interplay between the trench-normal slab-pull forces and lateral-shear forces set up by the strike-parallel components of the interplate-coupling resistance and the mantle-drag forces.

SEISMIC ATTRIBUTE ANALYSIS FOR HYDROCARBON PROSPECTING IN THE AGBADA FORMATION OF 'ZEE' FIELD, NIGER DELTA BASIN

The unconsolidated sandstone reservoirs of the Tertiary Nigeria Delta basin are prone to anomalous high amplitude seismic reflections from both hydrocarbon and non-hydrocarbon sources. In order to identify anomalous zone due to hydrocarbon presence, seismic attribute analysis was used to investigate the reservoirs and to detect Direct Hydrocarbon Indicators (DHIs) due to hydrocarbon saturation in the ‘Zee’ field reservoirs. The 3D seismic, well logs and checkshot data were used for structural interpretation which helped to identify the sandstone and hydrocarbon bearing reservoirs. Faults planes and horizon were mapped to highlight the structural geometry and reservoir surface detection respectively. Five different seismic attributes were used to qualitatively evaluate hydrocarbon prospect from seismic amplitudes. Seismic attributes revealed three (3) major normal growth faults across the field while two (2) reservoirs (shallow seated reservoir A and deep reservoir B) showed zones that contain hydrocarbon anomalies. Seismic amplitude responses and fault styles from the reservoir tops reveal structurally controlled fault dependent closure across the field. High seismic amplitude anomalies from RMS, Average Energy and Maximum Magnitude attributes significantly characterize the drilled parts of the field. This implies that the high amplitude anomaly is a DHIs in ‘Zee’ Field. Moreover, apart from the already producing zone in the field's central area, two (2) more areas marked X and Y situated on anticlinal structure at the North East corner of the field has similar high amplitude responses (bright spots). It suggests new hydrocarbon prospects that should further be investigated for more hydrocarbon discoveries.

Earthquake Fault Rupture Modeling and Ground-Motion Simulations for the Southwest Iceland Transform Zone Using CyberShake

ABSTRACT CyberShake is a high-performance computing workflow for kinematic fault-rupture and earthquake ground-motion simulation developed by the Statewide California Earthquake Center to facilitate physics-based probabilistic seismic hazard assessment (PSHA). CyberShake exploits seismic reciprocity for wave propagation by computing strain green tensors along fault planes, which in turn are convolved with rupture models to generate surface seismograms. Combined with a faultwide hypocentral variation of each simulated rupture, this procedure allows for generating ground-motion synthetics that account for realistic source variability. This study validates the platform’s kinematic modeling of physics-based seismic wave propagation simulations in Southwest Iceland as the first step toward migrating CyberShake from its original study region in California. Specifically, we have implemented CyberShake workflows to model 2103 fault ruptures and simulate the corresponding two horizontal components of ground-motion velocity on a 5 km grid of 625 stations in Southwest Iceland. A 500-yr-long earthquake rupture forecast consisting of 223 hypothetical finite-fault sources of Mw 5–7 was generated using a physics-based model of the bookshelf fault system of the Southwest Iceland transform zone. For each station, every reciprocal simulation uses 0–1 Hz Gaussian point sources polarized along two horizontal grid directions. Comparison of the results in the form of rotation-invariant synthetic pseudoacceleration spectral response values at 3, 4, and 5 s periods are in good agreement with the Icelandic strong motion data set and a suite of empirical Bayesian ground-motion prediction equations (GMPEs). The vast majority of the physics-based simulations fall within one standard deviation of the mean GMPE predictions, previously estimated for the area. At large magnitudes for which no data exist in Iceland, the synthetic data set may play an important role in constraining GMPEs for future applications. Our results comprise the first step toward comprehensive and physics-based PSHA for Southwest Iceland.

Improving Visible Light Photocatalysis Using Optical Defects in CoOx-TiO2 Photonic Crystals.

The rational design of photonic crystal photocatalysts has attracted significant interest in order to improve their light harvesting and photocatalytic performances. In this work, an advanced approach to enhance slow light propagation and visible light photocatalysis is demonstrated for the first time by integrating a planar defect into CoOx-TiO2 inverse opals. Trilayer photonic crystal films were fabricated through the successive deposition of an inverse opal TiO2 underlayer, a thin titania interlayer, and a photonic top layer, whose visible light activation was implemented through surface modification with CoOx nanoscale complexes. Optical measurements showed the formation of "donor"-like localized states within the photonic band gap, which reduced the Bragg reflection and expanded the slow photon spectral range. The optimization of CoOx loading and photonic band gap tuning resulted in a markedly improved photocatalytic performance for salicylic acid degradation and photocurrent generation compared to the additive effects of the constituent monolayers, indicative of light localization in the defect layer. The electrochemical impedance results showed reduced recombination kinetics, corroborating that the introduction of an optical defect into inverse opal photocatalysts provides a versatile and effective strategy for boosting the photonic amplification effects in visible light photocatalysis by evading the constraints imposed by narrow slow photon spectral regions.