Fault Surface Research Articles

Is the Mesochori Fault a Key Structure for Understanding the Earthquake Activity during the 2021 Damasi Earthquakes in Northern Thessaly, Greece?

On 3 March 2021, an important seismic sequence started in northern Thessaly, Greece. The Damasi Seismic Sequence (DSS) deformed the western sector of the Tyrnavos Graben, which includes a major blind normal fault and the Titarisios River Graben (TRG). In this contribution, we provide fieldwork observations across the TRG and satellite radar interferometry of the faults controlling the graben. In addition, we provide a map of the active faults exposed in the TRG and palaeoseismological analyses of the Mesochori Fault, which together contribute to unravelling the seismic history of the area. DInSAR provides clear evidence of the Mesochori Fault surface rupture during the main shocks, while our palaeoseismological analyses document a long seismic history of the fault, with a mean recurrence interval of 1.0–1.5 ka and a mean slip per event of ~15 cm for the last four events reactivating the scarp. Quantitative geomorphological analyses based on real-time kinematic (RTK) measurements with global navigation satellite system (GNSS) receivers and data from UAV flight campaigns also provide evidence of postseismic activity across the Mesochori Fault. Based on these results showing that (at least) the Mesochori Fault has been reactivated several times in the latest Quaternary the seismotectonics of the TRG are discussed.

Active Dipping Interface of the Southern San Andreas Fault Revealed by Space Geodetic and Seismic Imaging

AbstractThe Southern San Andreas Fault (SSAF) in California is one of the most thoroughly studied faults in the world, but its configuration at seismogenic depths remains enigmatic in the Coachella Valley. We use a combination of space geodetic and seismic observations to demonstrate that the relatively straight southernmost section of the SSAF, between Thousand Palms and Bombay Beach, is dipping to the northeast at 60–80° throughout the upper crust (<10 km), including the shallow aseismic layer. We constrain the fault attitude in the top 2–3 km using inversions of surface displacements associated with shallow creep, and seismic data from a dense nodal array crossing the fault trace near Thousand Palms. The data inversions show that the shallow dipping structure connects with clusters of seismicity at depth, indicating a continuous throughgoing fault surface. The dipping fault geometry has important implications for the long‐term fault slip rate, the intensity of ground shaking during future large earthquakes, and the effective strength of the southern SAF.

Running safety analysis of a train-bridge coupled system under near-fault ground motions considering rupture directivity effects

The implementation of China’s high-speed railroad network and the “Bridges Instead of Roads” construction concept has raised concerns over earthquake safety. The complex mechanism of near-field ground motions poses greater risks than far-field ground motions due to the rupture directivity effect, and Hanging-wall/Footwall effects. The PEER earthquake database lacks earthquake records with fault distances less than 20 km, making it difficult to study train running safety (TRS) under near-fault ground motions. To address this issue, an empirical formulation method is adopted for near-fault three-dimensional seismic synthesis that considers source and site characteristics as well as rupture directivity effects using regression analysis. The method is verified with respect to directivity pulse and a train-bridge coupled system (TBCS) model is developed to verify its accuracy under earthquakes. Responses of the TBCS model under near-fault ground motions synthesized with different fault types, closest distances to the fault surface, and directivity parameters are analyzed by taking the average of the largest part of the response for comparison. Results show that dip-slip faults pose a greater danger than strike-slip faults, and the main reason for the hazard caused by rupture directivity effects is the generation of a forward directivity pulse, which makes the TBCS highly susceptible to derailment under near-fault pulse-like ground motions.

Ptolemy-Pliny-Strabo Fay Zonu'nun Bozburun Yarımadası'ndaki (güneybatı Türkiye) etkisi: Yapısal verilerden ve odak mekanizma çözümlerinden elde edilen kanıtlar

Structural data obtained from fault surfaces in the Bozburun Peninsula, southwest Türkiye indicate that the previously known active normal faults are indeed strike-slip structures. The configuration of left- and right-lateral strike-slip segments and lineaments observed from high-resolution satellite images, plus the evaluation of available focal mechanism solutions of the earthquakes having less than 30 km depth around Bozburun Peninsula, show that the study area is under influence of the left-lateral Ptolemy-Pliny-Strabo Fault Zone.

Effect of normal fault activity on carbonate reservoir diagenetic evolution (Urgonian facies, SE France)

In carbonates rocks, which are sensitive to fluid-rock interactions, diagenetic processes can strongly modify the structure and volume of pore pattern. In highly reactive carbonate rocks, fault zone related fluid flow can increase diagenetic alterations (dissolution, replacement, cementation deposits). To define the diagenetic evolution of faulted rock as an analog to nearby reservoirs, we studied the diagenetic properties of Urgonian (upper Barremian) microporous limestones affected by a polyphase normal fault located on the northern flank of Nerthe anticline (SE France). Eight different cements have been identified under cathodoluminescence (C0 to C7). Their distributions and geochemical signatures (18O and 13C stable isotopes, Δ47 thermometry) allowed to determine the paragenetic sequence, as well as the origin (marine, meteoric, burial brines) and temperature of the fluids that generated C1 and C7 cements. U–Pb dating allowed us to relate the C7 cement phases with the Oligo-Aquitanian rifting stages. However, the results show that most of the diagenetic alterations occurred prior to the Cenomanian. Subsequently, localized but intense alteration related to the fault is limited to one stratigraphic unit, where effect extend as much as 700 m from the fault surface.

The 2022, Ms 6.9 Menyuan earthquake: Surface rupture, Paleozoic suture re-activation, slip-rate and seismic gap along the Haiyuan fault system, NE Tibet

The January 8, 2022, Ms 6.9 Menyuan earthquake occurred near the junction between the western Leng Long Ling (LLL) and eastern Tuolai Shan (TLS) faults, along the Haiyuan fault system, further illuminating the geometry of that system. Based on unmanned aerial vehicle (UAV) high-resolution images and field investigation, we mapped the fault geometry and surface ruptures, and measured co-seismic offsets in detail. Our results indicate that the event ruptured both a NWW-striking, ∼ 22 km-long segment of the west LLLF and a ∼ EW-striking, ∼ 4 km-long eastern segment of the TLSF, with maximum left-lateral displacements of ∼ 3.4 and 0.95 m, respectively. Both ruptures isolate a 2.8 km-wide, left-stepping, step-over/pull-apart, rather than a releasing bend as previously inferred. However, the two faults may connect continuously at depth, as suggested by both the aftershock distribution and the interferometric synthetic aperture radar (InSAR) data inversion, following the deep Paleozoic Qilian Shan suture, which is marked at the surface by discontinuous, elongated outcrops of ultramaphic rocks. Much larger, longer-term offsets of up to ∼ 71 and 55 m along the TLS and LLL, respectively, may have accrued since the end of the last glacial maximum (LGM, ∼20 ka) and the beginning of the Holocene (∼10 ka), respectively. This may be taken to imply average slip-rates since such times of ∼ 5 ± 0.5 and 3.5 ± 0.4 mm/yr along the LLLF and TLSF, respectively, consistent with extant InSAR/GPS rates. Based on our new UAV-based field survey and recent trenching results (Shi et al., 2019), we infer that neither the LLL nor the Gulang faults ruptured during the 1927, M 8 Gulang earthquake. The co-seismic Coulomb stress increased east of the 2022 Menyuan rupture. This, and the fact that the east-central LLLF does not appear to have ruptured in the last several hundred years may enhance the risk of occurrence of a Mw 7.4 earthquake along it. This might also imply that a large (M 8?) earthquake might rupture that segment, together with the ∼200 km-long Tianzhu seismic gap along the Haiyuan fault farther east, during a pending cascading event.

Rapid Source Characterization of the 2023 Mw 6.8 Al Haouz, Morocco, Earthquake

Abstract The U.S. Geological Survey (USGS) National Earthquake Information Center (NEIC) estimates source characteristics of significant damaging earthquakes, aiming to place events within their seismotectonic framework. Contextualizing the 8 September 2023, Mw 6.8 Al Haouz, Morocco, earthquake is challenging, because it occurred in an enigmatic region of active surface faulting, and low seismicity yet produced significant damage and loss of life. Here, we present the rapid earthquake source products produced by the USGS NEIC, describing how the source model was derived using both seismic and geodetic observations. Our analysis indicates that the earthquake was the result of oblique-reverse faulting in the lower crust on either a steeply north-dipping fault or a moderately south-dipping fault. Finite-slip models using seismic and geodetic data reveal a compact source, with slip occurring at depths of 15–35 km. The causative fault is not apparent, because the rupture did not break the surface, and it is not possible to definitively attribute the earthquake to a known structure. The earthquake centroid depth of 25 km is noteworthy, because it shows slip extending beyond common estimates of seismogenic depth. This earthquake highlights that the seismogenic processes associated with mountain building in this wide plate boundary region are poorly understood.

Evaluation Method of Potato Storage External Defects Based on Improved U-Net

The detection of potato surface defects is the key to ensuring potato storage quality. This research explores a method for detecting surface flaws in potatoes, which can promptly identify storage defects such as dry rot and the shriveling of potatoes. In order to assure the quality and safety of potatoes in storage, we used a closed keying method to obtain the pixel area of the mask image for a potato’s surface. The improved U-Net realizes the segmentation and pixel area measurement of potato surface defects and enhances the feature extraction capability of the network model by adding a convolutional block attention module (CBAM) to the baseline network. Compared with the baseline network, the improved U-Net showed a much better performance with respect to MIoU (mean intersection over union), precision, and Fβ, which were improved by 1.99%, 8.27%, and 7.35%, respectively. The effect and efficiency of the segmentation algorithm were also superior compared to other networks. Calculating the fraction of potato surface faults in potato mask images allows for the quantitative detection of potato surface problems. The experimental results show that the absolute accuracy of the quantitative potato evaluation method proposed in this study was greater than 97.55%, allowing it to quantitatively evaluate potato surface defects, provide methodological references for potato detection in the field of deep processing of potatoes, and provide a theoretical basis and technical references for the evaluation of potato surface defects under complex lighting conditions.

Study of the Interseismic Deformation and Locking Depth along the Xidatan–Dongdatan Segment of the East Kunlun Fault Zone, Northeast Qinghai–Tibet Plateau, Based on Sentinel-1 Interferometry

The East Kunlun fault zone (EKFZ), located northeast of the Qinghai–Tibet Plateau, has experienced several strong earthquakes of magnitude seven or above since 1900. It is one of the most active fault systems and is characterized by left-lateral strike-slip. However, the Xidatan–Dongdatan segment (XDS) of the East Kunlun fault zone (EKFZ) has had no earthquakes for many years, and the Kunlun Mountains MS 8.1 earthquake has a stress loading effect on this segment, so it is widely regarded as a high-risk earthquake gap. To this end, we collected the Sentinel-1 data of the XDS of the EKFZ from July 2014 to July 2019 and obtained the high-precision interseismic deformation field by the Interferometric Synthetic Aperture Radar (InSAR) technique to obtain the slip rate and locking depth of the XDS of the EKFZ, and the seismic potential of the segment was analyzed. The results are as follows: (1) The LOS deformation field of the XDS of the EKFZ was obtained using Sentinel-1 data of ascending and descending orbits, which indicated that the XDS of the EKFZ is dominated by horizontal motion. Combined with the interference results, it is shown that the strike-slip rate dominates the deformation information of the XDS of the EKFZ. The deep strike-slip rate of the fault is about 6 mm/yr, the deep dip-slip rate is about 2 mm/yr, and the slip-deficit rate on the fault surface is about 6 mm/yr; (2) Combined with the spiral dislocation theory model, the slip rate of the XDS to Xiugou Basin of the EKFZ has a gradually increasing trend, with an average slip rate of 9.6 ± 2.3 mm/yr and a locking depth of 29 ± 5 m; (3) The stress accumulation is about 483 ± 92 years in the XDS of the EKFZ, indicating that the cumulative elastic strain energy of the XDS can produce an MW 7.29 ± 0.1 earthquake in the future.

Inferring damage state and evolution with increasing stress using direct and coda wave velocity measurements in faulted and intact granite samples

SUMMARY A better understanding of damage accumulation before dynamic failure events in geological material is essential to improve seismic hazard assessment. Previous research has demonstrated the sensitivity of seismic velocities to variations in crack geometry, with established evidence indicating that initial crack closure induces rapid changes in velocity. Our study extends these findings by investigating velocity changes by applying coda wave interferometry (CWI). We use an array of 16 piezoceramic transducers to send and record ultrasonic pulses and to determine changes in seismic velocity on intact and faulted Westerly granite samples. Velocity changes are determined from CWI and direct phase arrivals. This study consists of three sets of experiments designed to characterize variations in seismic velocity under various initial and boundary conditions. The first set of experiments tracks velocity changes during hydrostatic compression from 2 and 191 MPa in intact Westerly granite samples. The second set of experiments focuses on saw-cut samples with different roughness and examines the effects of confining pressure increase from 2 to 120 MPa. The dynamic formation of a fracture and the preceding damage accumulation is the focus of the third type of experiment, during which we fractured an initially intact rock sample by increasing the differential stress up to 780 MPa while keeping the sample confined at 75 MPa. The tests show that: (i) The velocity change for rough saw cut samples suggests that the changes in bulk material properties have a more pronounced influence than fault surface apertures or roughness. (ii) Seismic velocities demonstrate higher sensitivity to damage accumulation under increasing differential stress than macroscopic measurements. Axial stress measured by an external load cell deviates from linearity around two-third through the experiment at a stress level of 290 MPa higher than during the initial drop in seismic velocities. (iii) Direct waves exhibit strong anisotropy with increasing differential stress and accumulating damage before rock fracture. Coda waves, on the other hand, effectively average over elastic wave propagation for both fast and slow directions, and the resulting velocity estimates show little evidence for anisotropy. The results demonstrate the sensitivity of seismic velocity to damage evolution at various boundary conditions and progressive microcrack generation with long lead times before dynamic fracture.

Evaluating the Compatibility of Hematite (U‐Th)/He Data and Hematite‐Carried Secondary Magnetizations: An Example From the Colorado Front Range

AbstractAncient magnetization(s), often recorded by hematite (Fe2O3), provide key paleomagnetic constraints on plate interactions through time. Primary remanent magnetizations may be modified or overprinted by secondary processes that complicate interpretations of paleomagnetic data. Hematite (U‐Th)/He (hematite He) dating has the potential to resolve when secondary magnetizations were acquired. Here, we compare hematite He data and paleomagnetic results in Paleoproterozoic crystalline rocks, meters below a major nonconformity in the Colorado Front Range, USA. Prior work and new rock magnetic data indicate that pervasive hematite alteration records a secondary chemical remanent magnetization (CRM) during the Permo‐Carboniferous Reverse Superchron, coincident with the Ancestral Rocky Mountain orogeny. We target minor hematite‐coated faults cutting basement for (U‐Th)/He analyses because they are of sufficient hematite purity to yield geologically meaningful dates. Two samples yield overlapping and scattered individual hematite He dates ranging from ∼138 to 27 Ma (n = 33), significantly younger than the age of the late Paleozoic CRM. Scanning electron microscopy, electron probe microanalysis, and Raman spectroscopy indicate that aliquots have variable grain size distributions and fluorocarbonate impurities. Thermal history models support hematite on fault surfaces mineralized coeval with CRM acquisition during the late Paleozoic, and hematite He data scatter reflects variable He loss during Mesozoic burial owing to differences in grain size distribution from fault slip comminution and in chemistry among aliquots. Our results underscore the differences in temperature sensitivity and sampling requirements between paleomagnetic and hematite He investigations and illustrate that hematite He dates will usually be younger than preserved remanent magnetizations.

Fault seal analysis for VS area, block 16 -1/15, Cuu Long Basin, Viet Nam

Fault-bound traps represent an important class of hydrocarbon-bearing structure. Whether a fault can seal hydrocarbons on a geological timescale may be controlled by one or more of three conditions: (1) sealing due to lithological juxtaposition, where reservoir rock is juxtaposed against sealing rock across the fault; (2) sealing by the fault damage zone, which forms a barrier composed of low-permeability clay within the fault zone and (3) the tectonic activity of the fault, as during faulting, hydrocarbon accumulations can be destroyed and leakage along the fault zone. This research employs an indirect method to establish a correlation between pressure and the sealing properties on fault surfaces, such as the SGR (Shale Gouge Ratio), across various formations under the same geological conditions from all fields within the region and around the world. This aids in assessing the sealing potential of the faults. Evaluate the fault seal capacity according to 3D model for the structures in Oligocene D, Oligocene C and Lower Miocene sediments to serve the assessment hydrocarbon potential in VS area and reduce the risk for further exploration - appraisal work in block 16-1/15, Cuu Long basin. Geology, seismic and petrophysical data were used to construct 3D structural frameworks, lithology model and Vclay model. Parameters such as fault throw, Vshale, lithology, bed thickness, burial depth history, fluid density and pressures, ect. are incorporated into fault seal analysis and also estimate the maximum hydrocarbon column height can be held by each fault in study area, therefore helping to assess the hydrocarbon potential in undrilled structures in VS area.

Stress and strain evolution in fault-related folds: insights from 2D geomechanical modelling

Fault-related folds are intriguing geological structures that develop in compressional and extensional regimes. These folds serve as structural traps for hydrocarbon resources, making their numerical models crucial for understanding the stress and strain evolution of hydrocarbon reservoirs. In our research, we utilize the two-dimensional finite element technique to simulate three representative categories of fault-related folds. Our investigation encompasses their geometric transformation over time, the distribution of stress and strain, variations in slip and uplift, and the effects that various mechanical properties have on these gradients. In our study, we uncovered essential findings about the behavior of fault-related folds. We ascertained that the fault slip gradient in the fault-bend fold model is less than in the fault-propagation fold model. Regarding the uplift gradient, the fault-propagation and fault-bend fold models displayed the greatest and the least degree of change, respectively. The trend of stress-strain evolution on the fold surface in all models was consistent, starting with an increase, transitioning to a constant phase, and ending with a decrease. This pattern proved to be more intricate and divergent than what was evident on the fault surface. Importantly, the internal friction angle, a crucial mechanical characteristic, had a significant influence on the development of these structures. This angle affected both the degree of uplift and stress; an increased angle resulted in enhanced uplift and stress, while a decrease resulted in a decline. Furthermore, the internal friction angle determined the compactness of the fold and the thickness of the forelimb, the part of the fold that inclines towards the advancing direction. These findings have enriched our knowledge of fault-related folds, highlighting the need to consider mechanical properties when studying their formation and evolution.

Geomechanical modeling of ultradeep fault‐controlled carbonate reservoirs and its application, a case of the Fuman Oilfield in Tarim Basin

AbstractTo improve the development efficiency of ultradeep fault‐controlled carbonate reservoirs, the deformation and connectivity mechanism of fractures was revealed through large‐scale rock mechanical experiments. The in situ stress field and fracture activity distribution law of fault‐control carbonate reservoirs were clarified through geomechanical modeling. It is revealed that the fracture activity in different directions and the connectivity of the fracture and cavity in different parts are significantly different, the development effect of different well trajectories is analyzed, and the integrated working method of geological engineering is proposed to scientifically guide the well trajectory design and water injection scheme optimization. The results show that: (1) Large‐scale fractures and high‐angle fracture systems in the deformation of strike–slip faults are the key factors affecting reservoir quality. High‐pressure water injection can activate preexisting fractures, and it can extend on the basis of preexisting fractures, and even generate new fractures, which promote the interconnection of fault‐controlled fracture‐cave bodies in the vertical and horizontal directions. (2) During the process of high‐pressure water injection, the coupling change between mechanics and flow occurs inside the fracture body, the seepage environment is improved, and the oil and gas recovery factor is improved through cyclic lifting. (3) According to the shape and occurrence of the fault body and the dynamic shear deformation connectivity of the fault surface, the best well point and well trajectory of the directional well can be optimized, and the water injection scheme can be optimized. (4) The single‐well production increased by 1.45 × 104 t through high‐pressure water injection, the cumulative oil increase of the same fracture‐cavity body increased by 4.63 × 104 t. This method is highly efficient for ultradeep fault‐controlled oil reservoirs. The development provides a good theoretical basis and technical support, and plays a leading and exemplary role.

A Methodology to Combine Shaking and Ground Failure Models for Forecasting Seismic Damage to Buried Pipeline Networks

ABSTRACT How does an earthquake affect buried pipeline networks? It is well known that the seismic performance of buried pipelines depends on ground failures (GFs) as well as strong ground shaking (SGS), but it is unclear how the various types of earthquake hazards should be collectively combined, as existing methodologies tend to examine each of the earthquake hazards separately. In this article, we develop a probability-based methodology to consistently combine SGS with three types of GF (surface faulting, liquefaction, and landslide) for forecasting seismic damage in buried pipeline networks from a given earthquake rupture scenario. Using a gas transmission pipeline example, we illustrate how the proposed methodology enables others (e.g., researchers, pipeline operators who manage distribution lines, and consultants) to modularly combine various models such as those for estimating probability of GF, permanent ground displacements, and pipeline fragility. Finally, we compare the proposed methodology against the Hazus methodology to explore implications from considering each hazard one at a time.

Detecting and approximating decision boundaries in low-dimensional spaces

A method for detecting and approximating fault lines or surfaces, respectively, or decision curves in two and three dimensions with guaranteed accuracy is presented. Reformulated as a classification problem, our method starts from a set of scattered points along with the corresponding classification algorithm to construct a representation of a decision curve by points with prescribed maximal distance to the true decision curve. Hereby, our algorithm ensures that the representing point set covers the decision curve in its entire extent and features local refinement based on the geometric properties of the decision curve. We demonstrate applications of our method to problems related to the detection of faults, to multi-criteria decision aid and, in combination with Kirsch’s factorization method, to solving an inverse acoustic scattering problem. In all applications we considered in this work, our method requires significantly less pointwise classifications than previously employed algorithms.

Mitigation of reverse faulting in foundation soils using geosynthetic-encased granular columns

In this study, a series of reduced model tests was conducted on soil foundations reinforced by Geosynthetic-Encased Granular Columns (GECs) placed across a reverse fault. These tests aimed at evaluating the effectiveness, reinforcing mechanism and optimal GEC horizontal spacing to mitigate the ground surface deformation associated with reverse faulting. For comparison, reduced model tests were also performed on unreinforced and Geosynthetic-Reinforced Soil (GRS) foundations. The reduced model tests were conducted to simulate a prototype 3-m-thick foundation layer subjected to a reverse fault displacement of 0.9 m. Digital Image Analysis (DIA) techniques were adopted to determine the surface displacement profile, angular distortion and shear rupture propagation considering various reverse fault offsets. Test results revealed that the GEC foundation can considerably reduce the fault-induced angular distortion at the ground surface. A reduction of 23.3% on the maximum angular distortion at the ground surface was observed as the fault displacement reached 30% of the foundation height (S/H = 30%), indicating the GEC foundation can mitigate the risk of surface fault hazards associated with large reverse fault movement. Two mechanisms, shear rupture diffusion and diversion effects, were identified for the GEC foundation, depending on the magnitude of the fault displacement and the system stiffness of the GEC foundation. Because of complex mechanisms between diversion and diffusion of the shear rupture in the GEC foundations, an optimal GEC spacing of Sh/dc = 3.3 was observed, which exhibited the most significant reduction in βmax at large fault offsets.

Fault-related sanctuaries of Mycenae (Greece): The Shaft Grave Circle A

Mycenae, one of the most important cities and sacred sites of antiquity in Greece, was built on a tectonic horst uplifted by active normal faults, and both faults show geologic evidence of recent coseismic slip. The Lion Gate fault, affecting the west slope of Mycenae, is described here through geological and archaeoseismological investigation. The tectonic offset since the Pliocene−Pleistocene sequence is 13−14 m. A 4−5-m-high scarp of the major splay of this fault, well preserved inside the Shaft Grave Circle A, exhibits tectonic geomorphological aspects typical of recent surface faulting. Mycenae experienced two earthquakes in ∼60 yr during its climax, one around 1250 B.C. and the other around 1190 B.C. Seismic damage at Shaft Grave Circle A was found to have occurred on more than one occasion. One event occurred with the earthquake of 1190 B.C., or more likely with a much later one, which cut the circular parapet. Heavy damages were also registered with the earthquake of 1250 B.C. An episode of surface faulting appears to have occurred shortly before the early graves were created in Shaft Grave Circle A (late seventeenth century B.C., Middle/Late Helladic period). The integration of available data suggests that the cults at Mycenae, particularly at Shaft Grave Circle A, deliberately chose specific sites or traits of the seismic fault as the central hub of their main sanctuaries. This occurrence was the result of a deliberate choice dictated by the fact that those sites along the fault trace were considered to be sacred and believed to be gateways to Hades.

Using shallow hydroacoustic data to image seafloor mass transport deposits on the North West Shelf of Australia: links to neotectonics

Abstract Mass transport deposits have long been known on the Exmouth Plateau, offshore NW Australia, identified in 2D and 3D industry seismic lines. The expedition SO257 in 2017 collected 30 high-resolution, shallow seismic lines along targeted transects on the northern Australian margin. Many of these imaged mass transport deposits, with the top 700–800 m of the section captured in detail not available with industry seismic data. We present nine new high-resolution seismic lines from three separate areas of the North West Shelf. Slides in the Roebuck Basin show complex anastomosing ductile extensional mechanisms, with multiple slip surfaces and no headscarps or adjacent faults. Slides on the Exmouth Plateau have fault control, with surface fault offsets of up to 300 m, indicating seismicity as a likely triggering mechanism. Slumps along the western margin of Western Australia are more limited in extent, associated with surface notches, with indications of previous activity at depth. All areas show a repeated history of mass transport deposits. The area of the active landslide province offshore of NW Australia is far larger than the individual slides recognized on the Exmouth Plateau.

Seismicity and Rock Burst Hazard Assessment in Fault Zones: a Case Study

The coal exploitation in the Upper Silesia region (along the Vistula River) triggers the strata seismic activity, characterized by very high energy, which can create mining damage of the surface objects, without any noticeable damages in the underground mining structures. It is assumed that the appearance of the high energy seismic events is the result of faults’ activation in the vicinity of the mining excavation. This paper presents the analysis of a case study of one coal mine, where during exploitation of the longwall panel no. 729, the high energy seismic events occurred in the faulty neighborhood. The authors had analyzed the cause of the presented seismic events, described the methods of energy decreasing and applied methods of prevention in the selected mining region. The analysis concluded that the cause of the high energy seismic events, during the exploitation of the longwall panel no. 729 was the rapid displacements on the fault surface. The fault’s movements arose in the overburden, about 250 m above the excavated longwall panel, and they were strictly connected to the cracking of the thick sandstone layer.