Trending Faults Research Articles

Interpreting Arc and Line Shapes in the Fault Ruptures of the 2016 Mw7.8 Kaikoura, New Zealand and the 2023 Mw7.8 and Mw7.6 East Anatolian Fault, Turkey-Syria Earthquakes: A Theoretical Approach

This study examined the arc and line shapes produced in the fault ruptures of the 2016 Mw7.8 Kaikoura earthquake in New Zealand and the 2023 Mw7.8 and Mw7.6 East Anatolian Fault earthquakes in Turkey-Syria. Theoretical fault mechanisms and physical laws of movement were used to interpret the conceptual geometry of the arc and line shapes, and kinematics force movement. Using computer-aided design (CAD) on the Universal Transverse Mercator (UTM) metric projection, this paper presents earthquake parameters defining the fault geometry, including straight lines and arc shapes with specific measurements such as radius, length, angles, and normal/perpendicular vectors. Comparative analysis revealed distinctions between the two seismic events. Specifically, the Kaikoura earthquake exhibited a smaller normal vector compared to the Turkey-Syria earthquakes. Further interpretation uncovered that the Kaikoura earthquake resulted from pressure exerted by the radius arc vector from both the south-east and north-west, aligning with the continuation of the north-easternmost fault rupture. This suggests that the primary fault vector aligns with the fault trend. In contrast, the Turkey-Syria earthquakes displayed two independent circuit systems. The first event in the Turkiye-Syria rupture underwent an orientation change or bending of about 137 degrees (from N24oE to N68oE). The normal vector of the second earthquake originated from the bending angle of the first earthquake, close to its hypocenter. The rupture of the Kaikoura earthquake followed a lineament orientation of N47oE, forming an approximately 10-km wide corridor, comprising both straight lines and arc shapes.

Geology of the Tabakoto gold deposit, Kédougou-Kéniéba Inlier, West African Craton, Mali

The Tabakoto gold deposit is part of the highly endowed west-Malian gold belt, which hosts several world-class deposits. This deposit, located in the Paleoproterozoic Kédougou-Kéniéba Inlier (KKI) of the West African Craton (WAC), is contained in Birimian metasedimentary rocks of the Kofi series that are intruded by magmatic dykes. The metasedimentary rocks are characterized by a S0/1 foliation delineated by the alternation of metagreywacke and meta-argillite. This foliation is affected by upright folds with N-S trending axial planes marked by a S2 schistosity and cross-cut by conjugate steep-dipping dextral NE-SW and sinistral NW-SE trending brittle faults. These structures record regional-scale E-W shortening, first associated with crustal thickening and then with N-S stretching, evolving from ductile to brittle deformation. The presence of the pyrrhotite-loellingite assemblage and the presence of scheelite is consistent with temperatures of upper greenshist facies (~ 430°C). Gold mineralization is found in sheared smoky quartz-pyrite veins in subvertical shear zones localized along the S2 schistosity and in S-shaped quartz-carbonate veins located in the NE-SW and NW-SE trending faults. The latter veins are marked by sodic alteration followed by carbonate (i.e., dolomite-ankerite ± calcite ± siderite) and phyllic (i.e., chlorite-muscovite-sericite) alterations. In the quartz-pyrite veins, gold occurs as inclusions in pyrite, arsenopyrite, and pyrrhotite, whereas in quartz-carbonate shear veins, gold is present in fractures cross-cutting pyrite and arsenopyrite and at the contact between pyrite and arsenopyrite or arsenopyrite and pyrrhotite. These features indicate that gold mineralization in the Tabakoto deposit results from hydrothermal fluid circulation during the Eburnean orogeny under ductile to brittle conditions, similar to other orogenic-type deposits in the WAC.

Rolling bearing fault diagnosis method based on adaptive signal diagnosis network and its application

Aiming at the problems of fixed convolution kernel size and poor targeting of extracted features in the application of deep learning in fault diagnosis, this paper develops a fault diagnosis framework called adaptive signal diagnosis network (ASDN), in which the EEMD of multi-scale signal decomposition is improved in the adaptive preprocessing stage to adaptively capture the transient changes of signals. Meanwhile, SSA is improved to further extract fault trends and periodic components to optimize the signal representation. In the adaptive deep learning stage, an innovative temporal convolutional network (TCN) with a dynamic adjustment mechanism was developed to enable the neural network to adjust its convolutional kernel size according to different frequency components so as to accurately process signals of different frequencies. Validation on datasets from Case Western Reserve University and Xi'an Jiaotong University shows the superior performance of the proposed method, with diagnostic accuracies of 100% and 97.42% on these two public datasets, respectively.

Surface and Deep Structure of the Hanshan–Wuwei Basins in the Lower Yangtze Region: Implications for Mesozoic Tectonic Evolution of the South China Block

AbstractIndicating the tectonic features of the Hanshan–Wuwei basin can reconstruct the framework of the basins formed in Mesozoic and further understand the Mesozoic tectonic evolution of the South China Block. Studies on surface structure, regional stress field and deep geophysical characteristics of the Mesozoic Hanshan–Wuwei basin in Lower Yangtze region were carried out. NE–NNE trending folds and faults developed in the northern margin of the basins. The reconstruction of tectonic stress fields indicates four stress stages dominating the basins' evolution including NW–SE compression, N–S compression, NW–SE extension and NWW–SEE compression. 2D seismic profiles reveal coexistence of thrust, strike‐slip and normal faults in the basin. Combined with regional geological studies, the geodynamic processes for the formation of the Hanshan–Wuwei basin can be divided into five stages: 1) During the Late Triassic, EW trending foreland basin was formed by N–S compression; 2) From Mid‐Jurassic to Late Jurassic, continuous compression strengthened the foreland deformation and formed thrust nappes. In this stage, the integrated foreland basin was compartmentalized or fragmented, and transferred to the broken foreland basin; 3) NE‐trending sinistral strike‐slip movement at the beginning of the Early Cretaceous; 4) Regional extension resulted in normal faults and rift basins developing in the Late Cretaceous; 5) The NWW–SEE compression at the end of the Late Cretaceous caused NW sinistral strike‐slip faults to form, which partly transformed the rift basin.

Structure and Evolution of Multi-Trend Faults in BZ19-6 Buried Hill of the Bohai Bay Basin, Eastern China

Defining the structure and evolution of multi-trend faults is critical for analyzing the accumulation of hydrocarbons in buried hills. Based on high-resolution seismic and drilling data, the structural characteristics and evolutionary mechanism of multi-trend faults were investigated in detail through the structural analysis theory and quantitative calculations of fault activity, allowing us to determine the implication that fault evolution exerts on hydrocarbon accumulation in the BZ19-6 buried hill. There are four kinds of strike faults developed on the buried hill: SN-, NNE-, NE–ENE-, and nearly EW-trending, which experienced the Mesozoic Indosinian, Yanshan, and Cenozoic Himalayan tectonic movements. During the Indosinian, the BZ19-6 was in a SN-oriented compressional setting, with active faults composed of SN-trending strike-slip faults (west branch of the Tanlu fault zone) and near EW-trending thrust faults (Zhang-peng fault zone). During the Yanshanian, the NNE-trending normal faults were formed under the WNW–ESE tensile stress field. Since the Himalayan period, the BZ19-6 buried hill has evolved into the rifting stage. In rifting stage Ⅰ, all of the multi-trend pre-existing faults were reactivated, and the EW-trending thrust faults became normal faults due to negative inversion. In rifting stage II, a large number of NE–ENE-trending normal faults were newly formed in the NW–SE-oriented extensional setting, which made the structure pattern more complicated. In rifting stage III, the buried hill entered the post-rift stage, with only part of the NNE- and NE–ENE-trending faults continuously active. Multi-trend faults are the result of the combination of various multi-phase stress fields and pre-existing structures, which have great influence on the formation of tectonic fractures and then control the distribution of high-quality reservoirs in buried hills. The fractures controlled by the NNE- and EW-trending faults have higher density and scale, and fractures controlled by NE–ENE trending faults have stronger connectivity and effectiveness. The superposition of multi-trend faults is the favorable distribution of high-quality reservoirs and the favorable accumulation area of hydrocarbon.

Targeting high-potential mineral prospects in the Ezzhiliga region, Moroccan central massif, using spectral data from the ASTER sensor

This research paper introduces a comprehensive methodology for assessing hydrothermal alteration zones and structural complexity in the Ezzhiliga region, situated in the Hercynian Central Massif of Morocco. The approach utilizes ASTER imagery as the primary data source. The main objectives were to identify and analyze these geological features and then create a potential map for mineral exploration by integrating fuzzy logic and fractal concentration area analysis. Band ratios (RBD) and principal component analysis (PCA) were employed to detect and map argillic, phyllic, propylitic, and iron oxide alteration zones. Additionally, structural lineaments were extracted from the PC1 imagery to understand the structural pattern of the survey area. The incorporation of hydrothermal alteration zones and structural lineaments was achieved through the application of a fuzzy logic model, resulting in the generation of a mineral favorability map. The fuzzy logic model was customized to combine hydrothermal alteration and lineaments density maps, effectively eliminating false spectral anomalies induced by various interference factors. This map was then analyzed using the fractal concentration-area (C-A) model, which separated the anomaly from the geological background and generated a final mineral potential map. Analysis of fractal concentration-area was employed to define thresholds with greater precision, enhancing the reliability of mineral prospectivity assessments. Furthermore, laboratory analyses were performed to verify the outcomes of the mineral potential map. The obtained results revealed a significant affinity with the field data and indicated that the highly prospective zones are perfectly limited in spatial extent and generally associated with the contact of the Zaër granitic pluton with the metamorphic host rock, except for the anomaly identified to the southeast of the study area, along a major NE-SW trending fault.

Resolution analysis of the gravity survey network in the middle and south sections of Tan-Lu fault and recent changes in the gravity field

In this paper, we computed the fractal dimension of three survey areas within the central and southern sections of the Tan-Lu fault zone using fractal analysis. Subsequently, simulations were conducted to analyze the gravity response under a forward model of equivalent density changes. Additionally, we thoroughly investigated the seismic monitoring capabilities of the gravity network in the central and southern regions of the Tan-Lu fault. Expanding on these analyses. Recent gravity field variations were examined in the mid-southern segment of the Tan-Lu fault zone and its surrounding areas from 2013 to 2023. The results indicate that the observation capabilities of the northern network in the study area outperform those of the southern gravity network, with the northern network demonstrating a more evenly distributed coverage. The optimal gravity anomaly recovery effect for the entire study area is achieved at a resolution of 0.5° × 0.5°. With an equivalent observable signal in the range of 30 × 10−8 m/s2 to 40 × 10−8 m/s2, the spatial resolution of the gravity network's field source is estimated to be approximately 55 km. From 2013 to 2023, a significant positive change has been observed in the gravity field within the study area. The Tan-Lu fault zone plays a crucial role in governing the crustal movement in this region, with the dextral strike-slip movement trend of the fault persisting. Small earthquakes occur more frequently in the southern section of the fault zone, while strong earthquakes are less common. The alignment of gravity field changes with the fault strike indicates ongoing activity in the fault zone without any signs of locking. In the central segment of the Tan-Lu fault zone in the Shandong region, there appears to be a weaker correlation between gravity field changes and fault trends. This discrepancy may suggest that the area is locked, resulting in the accumulation of stress and strain. It is imperative to monitor the continuous evolution of the gravity field in this region to gain insights into potential seismic risks.

Tectonic evolution of the eastern margin of the Northern South Yellow Sea Basin in the Yellow Sea since the Late Cretaceous

The South Yellow Sea Basin is the largest sedimentary basin in the Yellow Sea. The Gunsan Basin in the central eastern part of the Northern South Yellow Sea Basin comprises the Western, Central, and Eastern Subbasins. The Eastern Subbasin marks the eastern margin of the South Yellow Sea Basin. Interpretation of multi-channel seismic profiles and balanced cross-section restoration of depth-converted seismic profiles reveal the structural characteristics and evolution of the Eastern Subbasin. The subbasin comprises three groups of faults: NW-SE, NE-SW, and NNE-SSW trending faults. The subsidence pattern of the subbasin, derived from the cross-section restoration analysis, indicates five distinguished evolution phases: (i) rapid subsidence in the Late Cretaceous, (ii) slow subsidence from the Paleocene to the Eocene, (iii) accelerated subsidence in the Oligocene, (iv) alternation of the uplift and subsidence in the Early Miocene, and (v) gradual subsidence since the Middle Miocene. The main and moderate subsidence can be explained by the combination of extension in the SE and NE-SW directions that formed double duplex structures. We suggest that the NW oblique subduction of the Pacific Plate under the NE Asia margin induced both extension toward the trench and dextral strike-slip parallel to the margin. The extension toward the trench caused SE transtension in a local pull-apart setting, whereas the dextral strike-slip parallel to the margin caused NE-SW extension, inducing more significant subsidence. The combined processes resulted in the progressive development of nested duplex structures. The evolution of the Eastern Subbasin is not compatible with previously suggested models for the western part of the South Yellow Sea Basin including foreland basin formation and transtension induced by branch faults of the Tan-Lu Fault.

Integrating remote sensing and geophysical data for mapping potential gold mineralization localities at Abu Marawat area, central Eastern Desert, Egypt

Abu Marawat area in the Central Eastern Desert of Egypt is a very promising mineralization district located in the Golden Triangle area. The current study provides an integrated approach from multisource datasets including; remote sensing, airborne geophysical spectrometry and magnetic data supported by field studies and spectroscopic analyses for delineating potential mineralization localities. Several remote sensing techniques were adopted including; Band Ratios, Relative Band Depth, Mineralogical Indices, Spectral Angle Mapper, and Constrained Energy Minimization. These techniques showed that the alteration mineral assemblage is mainly, kaolinite, sericite, and iron oxides, with less abundant chlorite, epidote, and carbonates. In addition, the radiometry data were processed to map the localities with the highest possibility of potassic alteration abundance by integrating the potassium distribution, K/eTh ratio, and the F-parameter maps. The surface and subsurface linear structural features were also mapped using Digital Elevation Model (DEM) and aeromagnetic data, respectively. The surface linear structures were found exhibiting E-W and NE-SW trends, while, the subsurface structures showed dominant NW–SE trend. All the depicted fault trends match well with the local and regional geological and tectonic setting of the study area suggesting structural control on the mineralization in this area. Integration between the results obtained from both the remote sensing and the geophysical data was conducted by a GIS weighted overlay model. The obtained mineralization potentiality map highlights eight potential localities for mineralization. The accuracy of the adopted methodology was demonstrated through fieldwork and spectral analyses; several alteration indicators were observed, including quartz veins, iron oxides, kaolinite, malachite, montmorillonite, chlorite, talc, and sericite alteration indicator minerals. The adopted remote sensing-geophysical approach showed being very effective for mapping the hydrothermal gold-related alteration zones, and is recommended for other similar investigations.

Satellite land surface temperature for mapping the structurally controlled geothermal anomalies in the Cretaceous rift, South Egypt

ABSTRACT Exploration of new geothermal systems often requires regional-scale investigation. Satellite Land Surface Temperature (LST) products are essential in geothermal anomaly identification and mapping. In this study, seven thermal anomalies covering Egypt were observed using the Sentinel-3 LST images acquired in 2019 and confirmed using the 2020 LST images. In addition, the LST analysis reveals three new anomalies covering the southern part of Egypt (Kalabsha, Natash, and Wadi Allaqi), which are structurally controlled. Nuqra-Kharit-Natash is a good site for geothermal energy owing to the following reasons: 1) the high geothermal gradient beneath the Wadi Natash region (heat flow ~100 mW/m2); 2) the presence of many geothermal anomalies retrieved from the analyses of the Landsat-8 acquired in August 2018; 3) existence of surface geothermal manifestation at the western boundary of the basin includes warm springs and the tufa deposits. Intricate structural patterns, including NW-oriented normal faults, ENE-to-WNW-oriented right-lateral faults, and NNE-oriented sinistral strike-slip faults, characterise Wadi Natash. Wadi Natash LST anomaly shows a solid relation to fault trends. High values of LST are arranged along NW and NNE faults and recorded the peak at the intersection of two fault trends. Recent seismic activity along the NNE fault system enhances the permeability along this trend and its intersection with the NW-oriented fault.

Imaging the Fault Plane Structure of Palu-Koro Fault from Earthquake Data Using Python

Abstract Palu-Koro Fault is one of the active faults located in Sulawesi and positioned in the middle of the Island, dividing the west and east-southeast arms. Its long history of earthquakes provides sufficient focal mechanisms data to be analyzed. This research used seven focal mechanism data of shallow magnitude earthquakes surrounding the pull-apart basin area of the Palu-Koro Fault. The focal mechanism data used is secondary data obtained containing the information needed. This research aims to create a 3D model of the pull-apart basin displaying the geometries of the fault planes and providing a closer look at the fault system surrounding the bounding fault zones. Python script was made to classify the mechanism of each earthquake based on its correlation to the trend of the Palu-Koro Fault. Nodal planes are categorized as whether it is presumed to be the fault plane or the auxiliary plane of the focal mechanism. The result found that not all earthquake data was classified through the assumed parameter set. Only five of seven earthquake data managed to be classified, while the rest showed a different focal mechanism. It is found from the python script created revealed the presence of three fault types: normal fault, normal left lateral oblique fault, and left lateral strike-slip. The 3D fault plane interpolation showed two distinct dipping directions, suggesting their association with the basin’s bounding fault, either the west or the east side. From the gathered information, previous research, and geological interpretation, the earthquake data can be concluded into three fault associations to the bounding fault: synthetic extension fault, antithetic extension fault, and sinistral strike-slip fault.

Chemical process fault detection and trend analysis based on KESN

AbstractFault detection has great significance for chemical process safety with the development of science and technology. The conventional echo state network‐based fault detection method does not highlight key fault features, and cannot forecast future fault trend after the occurrence of faults. For the above problems, a chemical process fault detection and trend analysis strategy based on key feature enhanced echo state network (KESN) is proposed. First, dynamic features are extracted by a detecting echo state network. Then, a weighting strategy is designed to enhance key features and increase fault detection rates. After detecting a fault, independent component analysis is utilized to extract independent key features. Future fault trend is forecasted based on the forecasting multi‐KESN. Simulation results on the Tennessee Eastman process demonstrate the effectiveness of the proposed method.

Information manifold and fault detection of multi-agent systems

With the increase of the number of agents in multi-agent systems and the rapid increase of the complexity of the overall structure of the system, the fault detection and diagnosis work has brought great challenges. Researchers have carried out considerable research work on fault detection and diagnosis of multi-agent systems, but there is no research on fault state estimation and diagnosis based on the information and state of the whole multi-agent system. Based on the global perspective of information geometry theory, this paper presents two new physical quantities of the information manifold of multi-agent systems, as Lagrangian and energy–momentum tensor, to express the state of the overall information of multi-agent systems, and to characterize the energy state and development trend of faults. In this paper, two new physical parameters are introduced into the research of multi-agent fault detection and diagnosis, and the fault state and trend of multi-agent system are evaluated from the global perspective, which provides more comprehensive theoretical support for designing more scientific and reasonable fault diagnosis and fault recovery strategies. Simulation of the application example confirms the competitive performance of the proposed method.

A High-Resolution subtle fault mapping in Marlin oilfield, Brazil

Discriminating geological discontinuities is important for reservoir management because they influence storage capacity and fluid flow. Structural heterogeneities, such as faults and fractures, significantly impact the compartmentalization of the reservoir’s facies and affect the flow of hydrocarbons. These structures can act as the pore space for fluid storage, flow-control conduits, or barriers that allow the accumulation of exploitable volumes of oil and gas. Understanding these structures’ spatial and temporal development can significantly impact hydrocarbon exploration. Reservoir characterization is a critical process in the oil and gas industry that aims to comprehensively understand reservoir rocks and their fluid content and distribution. It is a multidisciplinary approach that combines geological, geophysical, and engineering datasets through statistical and deterministic mathematical models. Seismic datasets play a crucial role in reservoir characterization. Interpreters can use seismic data processing and imaging to interpret geological horizons and map faults, building complex geological models. Seismic inversion is also employed to estimate acoustic impedance and other petrophysical properties. Faults and fractures mapping are highly relevant themes in reservoir characterization. Identifying subtle faults and fractures is essential in specifying hydrocarbon migration paths and identifying bypassed oil accumulations. However, traditional seismic amplitude data interpretation should consider these structures more. In this study, we apply a high-resolution fault mapping workflow to map the subtle faults system at the Marlim field in the offshore portion of the Campos Basin. As an outcome, we imaged two separate fault trends inside and outside the Marlim reservoir.

Structural framework of the Caswell Sub-basin, North West Shelf, Australia

The Caswell Sub-basin, situated within the Browse Basin in the North West Shelf constitutes one of Australia’s primary hydrocarbon producing regions, with notable gas-condensate producing fields including Ichthys and Prelude. Jurassic syn-rift sandstones are extensively distributed across the basin and serve as one of the major reservoirs. However, reservoir sequences are typically intensely faulted and exhibit heterogeneity in thickness and lithofacies, with some areas experiencing localised erosion on uplifted fault blocks (e.g. Northern Caswell Sub-basin). Hence, understanding the nature of the 3D fault patterns and their growth history is crucial for evaluating the reservoir characteristics for field development and additional exploration activities. This study, therefore, aims to evaluate the structural framework and the tectonic evolution of the Caswell Sub-basin. Detailed structural interpretation of Paleozoic and younger sequences was conducted using multiple 3D seismic datasets extending over Ichthys, Prelude, Lasseter, and Crown fields. Our study focuses mainly on Mesozoic faulting patterns and kinematics evaluated from interpreted structural maps, thickness changes of each stratigraphic interval and fault throw profiles of major bounding faults. The extensional phase during the Early–Middle Jurassic triggered the development of NE–SW trending faults and the deepening of the Brewster Graben. While, from the Late Jurassic to the Early Cretaceous, the development of E–W trending faults in the north of the Crown and Lasseter fields indicate a shift in the regional stress regime. We highlight the importance of evaluating the structural linkage from basement to cover sequences to achieve a comprehensive understanding of reservoirs and associated petroleum systems.

New insights into the origin and depositional setting of the Haerdaban Pb[sbnd]Zn deposit, Chinese western Tianshan: Evidence from geology, chert geochemistry, and detrital zircon U[sbnd]Pb geochronology

The Haerdaban PbZn deposit (with an ore reserve of 10.93 Mt. at 1.0–25.65 % Zn and 0.7–12.29 % Pb) is hosted in weakly metamorphosed clastic‑carbonate rocks from the Proterozoic Haerdaban Group. It represents a significant addition of the sediment-hosted PbZn deposits in the Yili block, Chinese western Tianshan. Currently, there are ongoing debates regarding its genesis, with a particular focus on the crucial metallogenic mechanism (syngenetic sedimentary exhalation or epigenetic reworking) responsible for the primary sulfide mineralization. Mineralization at Haerdaban primarily occurs as banded to stratiform ore layers or lenses conformably sandwiched in their host rocks. Vein and stockwork ores occur locally below the stratiform ore layers. A syn-sedimentary fault trending SN was identified based on abrupt lateral changes in lithofacies and thickness of the stratigraphic units. The ore mineralogy is dominated by sphalerite, galena, quartz, and dolomite, with a small amount of pyrite, barite, and organic matter. Detrital zircon LA-ICP-MS UPb dating of the Haerdaban siltstones obtained a maximum depositional age of about 604 Ma. Their geochemical composition similar to the passive continental margin signatures, with rare earth element (REE) patterns enriched in LREE and negative Eu anomalies (Eu/Eu* = 0.50–1.14). Stratiform beds of chert that host disseminated ores have relatively high contents of hydrothermal components (e.g., Ba, Zn), with apparent positive Eu anomalies (Eu/Eu* = 7.38–49.34) and negligible negative Ce anomalies (Ce/Ce* = 0.85–0.98). They are thus interpreted to be hydrothermal sedimentary rocks (exhalites) deposited in a suboxic-anoxic environment proximal to the hydrothermal vents. Integrated geological and geochemical evidence indicates that the Haerdaban PbZn deposit is a typical vent-proximal sedimentary exhalative (SEDEX) deposit formed in a Neoproterozoic Sinian (Ediacaran) passive continental margin rift basin. Post-depositional metamorphism and deformation in the Paleozoic may have caused partial remobilization of primary ores but did not significantly alter the morphology of the orebodies. Furthermore, establishing a genetic model for the Haerdaban deposit has important implications for the exploration of similar deposits preserved in the equivalent stratigraphy within the Chinese western Tianshan region.

Long live the fault! Double inversion of a Mesozoic rift‐related fault system in the central Apennines

AbstractThe San Potito area in central Apennines (Italy), enclosed within the Latium‐Abruzzi carbonate platform, exposes anomalously pelagic carbonates filling an intraplatform basin formed during Jurassic rifting. Oriented obliquely to the regional NW‐SE trend of Cenozoic thrusts and extensional faults, the basin's eastern boundary fault system, striking N‐S, played a pivotal role in structuring orogenic and post‐orogenic features. Large tracts of the fault experienced double reactivation: positive inversion during Miocene shortening, and negative during post‐orogenic extension. Double reactivation is evidenced by older‐on‐younger extensional contacts, and by the change in orientation of thrusts and recent extensional faults from NW‐SE to NNW‐SSE, the latter being consistent with the trend of Jurassic rift‐related structures of the area. This structural interplay highlights the importance of Jurassic faults and their ability in forcing the structural trends, by surviving across multiple deformation stages, even controlling active extensional seismicity.

Online Piecewise Convex-Optimization Interpretable Weight Learning for Machine Life Cycle Performance Assessment.

Machine life cycle performance assessment is of great significance to use a health index to inform the time of incipient fault initiation in a normal stage and realize fault identification and fault trending in a performance degradation stage. However, most existing works consider using unexplainable model parameters and historical data to build models and infer their off-line parameters for machine life cycle performance assessment. To overcome these limitations, an online piecewise convex-optimization interpretable weight learning framework without needing any historical abnormal and faulty data is proposed in this article to generate a piecewise health index to practically implement machine life cycle performance assessment. Firstly, based on a separation criterion, the first submodel in the proposed framework is built to detect the time of incipient fault initiation. Here, the piecewise health index generated by the first submodel is continuously updated by on-line monitoring data to timely detect the occurrence of any abnormal health conditions. Secondly, once the time of incipient fault initiation is informed, online updated model weights are highly correlated with fault characteristic frequencies and informative frequency bands for immediate fault identification. Simultaneously, the second submodel integrated with monotonicity and fitness properties in the proposed framework is triggered to generate the piecewise health index to realize overall monotonic fault trending. The significance of this article is that only online monitoring data are used to continuously update interpretable model weights as fault frequencies and informative frequency bands to generate the proposed piecewise health index so as to practically realize machine life cycle performance assessment. Two run-to-failure cases are studied to show the effectiveness and superiority of the proposed framework.

An adaptive strategy for time‐varying batch process fault prediction based on stochastic configuration network

AbstractFault prediction ensures safe and stable production, and cuts maintenance costs. Due to the changing operating conditions that lead to the changes in the characteristics of industrial processes, there is a need to monitor the fault state of batch processes in real‐time and to accurately predict fault trends. An adaptive slow feature analysis‐neighborhood preserving embedding‐improved stochastic configuration network (SFA‐NPE‐ISCN) algorithm for batch process fault prediction is proposed. Firstly, SFA is used to extract the time‐varying features of process data and establish the update index of the NPE model. Then, to extract local nearest‐neighbor features and reconstruct them by the NPE model with adaptive update capability, square prediction error (SPE) statistics are constructed as fault state features based on the reconstructed error. Further, the hunter‐prey optimization (HPO) algorithm optimizes the weights and biases in the stochastic configuration network, and the singular value decomposition (SVD) and QR decomposition of column rotation are introduced to solve the ill‐posed problem of SCN and obtain the prediction model of ISCN. Finally, the obtained statistics SPE is formed into a time series, and the ISCN model is used to predict the process state trend. The effectiveness of the proposed algorithm is verified by case studies of industrial‐scale penicillin fermentation processes and the Hot strip mill process.

In-situ rock shattering and strain localization along a seismogenic fault in dolostones (Monte Marine fault, Italian Central Apennines)

In-situ shattered rocks are often associated with seismogenic fault zones, but their mechanism of formation is still matter of debate, partly because of the limited number of field studies. Here we describe the characteristics of in-situ shattered rocks distribution along the NW-SE-striking seismogenic Monte Marine Fault (MMF) in the Italian Central Apennines. In the studied area, the MMF cuts through Mesozoic carbonates, is exhumed from <3 km depth and consists of two >5 km-long major hard-linked segments with normal kinematics. The linkage between the two fault segments occurs along a ∼2 km-long step-over zone with E-W trending faults and oblique-slip kinematics. To the northwest, fault-related shear deformation is localized in a ∼5 m-thick cataclastic fault core and off-fault deformation is dominated by in-situ shattered rocks up to ∼40 m-thick. Instead, in the step-over zone to the southeast, the in-situ shattered rocks are up to ∼500 m thick, particularly where MMF crosscuts older low-angle thrust faults.We integrated detailed field structural surveys with microstructural and grain size distribution analyses of the fault rocks to assess the mechanism of (1) formation of in-situ shattered rocks and, (2) progressive localization of shear deformation along the MMF. The obtained results, after the viability of several formation mechanisms (mechanical models) have been reviewed, support the hypothesis that the formation of in-situ shattered rocks was associated with the propagation of (multiple) seismic ruptures (mainshocks and aftershock sequences) within a mechanically heterogeneous fault zone. Heterogeneity is due to the occurrence of preexisting damage related to previous earthquakes, but also inherited from the older low-angle thrust faults. Therefore, we suggest that the origin of these shattered rocks is more compatible with seismic related processes than only with quasi-static fault growth models. On the other hand, the cataclastic fault core derived from the progressive accommodation of shear deformation within the in-situ shattered rock volumes during several seismic cycles. We conclude that the large volumes of in-situ shattered rocks are the result of seismic-related dissipative processes in a geometrically and mechanically heterogeneous fault zone. In this scenario, large volumes of in-situ shattered rocks are compliant low velocity zones which can influence the propagation of earthquake ruptures.