Active Faults Research Articles

Development of physical model test system for fault-slip induced rockburst in underground coal mining

A complex geological environment with faults can be encountered in the process of coal mining. Fault activation can cause instantaneous structure slipping, releasing a significant amount of elastic strain energy during underground coal mining. This would trigger strong rockburst disasters. To understand the occurrence of fault-slip induced rockbursts, we developed a physical model test system for fault-slip induced rockbursts in coal mine drifts. The boundary energy storage (BES) loading apparatus and bottom rapid retraction (BRR) apparatus are designed to realize energy compensation and continuous boundary stress transfer of the surrounding rocks for instantaneous fault slip, as well as to provide space for the potential fault slip. Taking the typical fault-slip induced rockburst in the Xinjulong Coal Mine, China, as the background, we conducted a model test using the test system. The deformation and stress in the rock surrounding the drift and the support unit force during fault slip are analyzed. The deformation and failure characteristics and dynamic responses of drifts under fault-slip induced rockbursts are obtained. The test results illustrate the rationality and effectiveness of the test system. Finally, corresponding recommendations and prospects are proposed based on our findings.

Variability of sequence architecture in a rift margin controlled by tectonic activity: The Eocene Dongying Depression, Bohai Bay Basin, China

AbstractSequence architectures along the margins of rift basins are still poorly documented compared to passive continental margin settings. The Eocene Shahejie Formation on the rift margin of the Dongying Depression records a complex sequence stratigraphic distribution of conglomerate, sandy conglomerate, sandstone and mudstone. These facies have been mainly attributed to fan delta and marginal subaqueous fan depositional settings that developed during segmented fault activity along the rift margin. We utilize three‐dimensional (3D) seismic data, conventional cores, and wireline log data to dissect the overall wedge‐shaped upper sub‐member strata of the Shahejie Formation's fourth member. The study interval is a third‐order sequence formed between 45.4 and 42.5 Ma and contains a lowstand–transgressive systems tract (LST–TST) and a highstand systems tract–falling‐stage systems tract (HST–FSST). We found that the LST–TST developed several huge amalgamated depocenters along the Chennan border fault; whereas, these depocenters gradually diminished or even disappeared during the HST–FSST period, illustrating less significant control by the border fault. Through calculations of strata growth rates, we confirmed that the segmented activity of the border fault influences the stratigraphic distribution and facies evolution during these two periods. Specifically, deep‐water depositional systems, represented by marginal subaqueous fans were widely developed in the LST–TST period and were influenced by overall strong tectonic activity, including retrogradational (R) and aggradational (A) patterns. However, the aggradational to progradational (AP) deltas and progradational to degradational (PD) deltas dominated the generally muted tectonic activity setting during the HST–FSST. Additionally, influenced by localized segmented fault activity, these systems tracts exhibit incomplete vertical development, resulting in spatial variability in stratigraphic stacking patterns.

Coupled Detachment Faulting and Hydrothermal Circulation at 49.7°E Southwest Indian Ridge Revealed by Seafloor Magnetism

AbstractDetachment faults at slow‐ and ultraslow‐spreading mid‐ocean ridges are essential for lithosphere‐hydrosphere interactions. However, their coupling with subseafloor hydrothermal circulation is poorly understood. Here, we investigated shallow hydrothermal fluid circulations in the active Dragon Horn detachment fault system of the Southwest Indian Ridge using combined near‐bottom magnetic anomaly data and rock magnetic analyses. We observed enhanced magnetic anomalies related to the high magnetization of basaltic country rocks and highly serpentinized (>80%) peridotite, whereas the hydrothermally altered basalts and sulfide deposits had weak magnetization and reduced magnetic anomalies. Therefore, the low‐magnetization zone was interpreted as a proxy for the hydrothermal fluid channel. The spatial distribution of the low‐magnetization zone revealed that the inactive Suye field expanded more than 500 m in diameter horizontally and ∼100 m vertically, and the active Longqi hydrothermal field had a >1 km fluid channel, both centered around the detachment fault fracture zone. Our results establish a robust link between detachment faulting and shallow hydrothermal circulation in which the detachment fault system provides critical fluid paths. Therefore, detachment tectonics are important elements for evolving seafloor hydrothermal fields along the Southwest Indian Ridge and possibly other slow‐ and ultraslow‐spreading mid‐ocean ridges globally.

The Response of Taupō Volcano to the M7.8 Kaikōura Earthquake

AbstractSeveral studies suggest that large earthquakes (M > 7.0) can act as external triggers of volcanic unrest, and even eruption. This triggering is attributed to either ground shaking (dynamic stresses) or to permanent ground deformation (associated with static stress changes). However, large earthquakes are rare and testing triggering hypotheses has proven difficult. We use geodetic data to show that the 13 November 2016 Kaikōura earthquake (Mw 7.8) triggered local deformation of up to 11 mm at Taupō volcano, 500 km away, which lasted for approximately twelve days. Using elastic geodetic models, we infer that the observed deformation was caused by either aseismic fault slip or a dike intrusion. We then use strong motion data from the surrounding area to show that the Kaikōura earthquake caused maximum dynamic stress changes in the range of 0.15–0.9 MPa in the vicinity of Taupō volcano and conclude that these dynamic stress changes triggered local faulting or dike activity and the associated deformation at Taupō volcano.

Probabilistic estimation of the source component of seismic hazard in North-Eastern Brazil

Stable continental regions pose unique challenges for conducting Probabilistic Seismic Hazard Analysis because the earthquake activity driving mechanisms are poorly understood. For instance, the lower seismicity (hence the paucity of data) and the absence of well-defined active fault systems complicate accurately determining seismic source parameters. Northeastern Brazil is a stable continental region exhibiting moderate-size events recorded with significant seismic intensities and provoking the collapse of poorly constructed buildings in the last century. Thus, assessing the seismic hazard is critical for seismic risk mitigation. The seismic hazard depends on three components: source, path, and site, and here, we present the probabilistic seismic hazard analysis of the source component for NE Brazil. Spatial aggregation of earthquake sources outlined four areal seismic zones. A goodness-of-fit test rejected the Gutenberg-Richter model of magnitude frequency distribution in one of the studied seismic zones. For this reason, we estimated the magnitude probability distribution function in that zone using a nonparametric adaptive kernel estimator. In other zones the Gutenberg-Richter magnitude frequency model was applied. In either way of the magnitude probability distribution modelling we considered the upper bound for magnitude equal to 6.6 mR, based on the upper bound of a 95 % confidence interval for the standard normal distribution of palaeoearthquake sizes. Our findings suggests that potentially damaging events are likely to occur, and we cannot neglect chances for the occurrence of earthquakes exceeding 5.2 mR. The calculated mean return periods indicate significantly shorter intervals between consecutive large events than palaeoseismic records.

Earthquake Relocations Delineate a Discrete Fault Network and Deformation Corridor Throughout Southeast Alaska and Southwest Yukon

AbstractDeformation in southeastern Alaska and southwest Yukon is governed by the subduction and translation of the Pacific‐Yakutat plates relative to the North American plate in the St. Elias region. Despite notable historical seismicity and major regional faults, studies of the region between the Fairweather and Denali faults are complicated by glacial coverage and the remote setting. In the last decade, significant improvements have been made to the density of regional broadband seismometer networks. We relocate more than 5,000 earthquakes between 2010 and 2021 in the region of southeastern Alaska and southwestern Yukon utilizing these improved seismic networks. With reductions in catalog uncertainty, particularly in depth, we quantify the thickness of the seismogenic layer in the crust throughout the region and locate seismicity on a shallow network of upper‐crustal faults. Relocated earthquakes, combined with an updated focal‐mechanism catalog, permit estimating and classifying motion of active faults. This includes mapping the Totschunda‐Fairweather “Connector” fault, which plays an important role in explaining regional deformation, and identifying new faults like the Kathleen Lake fault. We draw similarities between our seismic observations and simplified conceptual models of regional tectonics, which describe a dominant transpressional regime and localized slip partitioning. Our results support a hypothesis where current deformation is taking place on a well‐defined and evolved network of shallow faults in the corridor between the Totschunda‐Fairweather “Connector” and Denali faults.

Origin of Philippine Sea Basins During Subduction Initiation in the Western Pacific

AbstractUnderstanding the age and dynamics of the overriding plates allows an assessment of competing subduction initiation hypotheses. The Izu‐Bonin‐Mariana margin in the Western Pacific is a key example of initiation and hence it is important to constrain the age and origin of the oldest igneous crust of the supra‐subduction Philippine Sea Plate. We present geochronological and geochemical data of igneous rocks from the oldest ocean basins of the Philippine Sea Plate: the West Philippine and Palau Basins. Basalts from these basins have enriched geochemical characteristics similar to the EM‐2‐like mantle component found in OIB‐like basalts associated with the Oki‐Daito mantle plume. Ages of basalts from the northernmost West Philippine Basin (WPB) and the Palau Basin range from 43.5 to 50.5 Ma, which is similar to the oldest samples associated with the Oki‐Daito mantle plume (48–50 Ma). This implies that the plume contributed to magmatism from the onset of basin formation. It also provides support for the proposition that rifting of the Mesozoic arc terrane and subsequent seafloor spreading of the WPB was triggered by the arrival of the Oki‐Daito mantle plume at the base of the lithosphere. The age of these Philippine Sea Basins implies that only the Mesozoic Daito Ridge Group and the Gagua Ridge existed as Philippine Sea Plate crust before subduction initiation. A major fault activity after 37 Ma in the northernmost WPB demonstrates that careful reconstruction of the Eocene Philippine Sea Plate is critical to understanding plate dynamics during subduction initiation in the Western Pacific.

Late Quaternary Surface Displacements on Accretionary Wedge Splay Faults in the Cascadia Subduction Zone: Implications for Megathrust Rupture

Because splay faults branch at a steep dip angle from the plate-boundary décollement in an accretionary wedge, their coseismic displacement can potentially result in larger tsunamis with distinct characteristics compared to megathrust-only fault ruptures, posing an enhanced hazard to coastal communities. Elsewhere, there is evidence of coseismic slip on splay faults during many of the largest subduction zone earthquakes, but our understanding of potentially active splay faults and their hazards at the Cascadia subduction zone remains limited. To identify the most recently active splay faults at Cascadia, we conduct stratigraphic and structural interpretations of near-surface deformation in the outer accretionary wedge for the ~400 km along-strike length of the landward vergence zone. We analyze recently acquired high-frequency sparker seismic data and crustal-scale multi-channel seismic data to examine the record of deformation in shallow slope basins and the upper ~1 km of the surrounding accreted sediments and to investigate linkages to deeper décollement structure. We present a new fault map for widest, most completely locked portion of Cascadia from 45 to 48°N latitude, which documents the distribution of faults that show clear evidence of recent late Quaternary activity. We find widespread evidence for active splay faulting up to 30 km landward of the deformation front, in what we define as the active domain, and diminished fault activity landward outside of this zone. The abundance of surface-deforming splay faults in the active outer wedge domain suggests Cascadia megathrust events may commonly host distributed shallow rupture on multiple splay faults located within 30 km of the deformation front.

Study on overburden failure characteristics and displacement rule under the influence of deep faults

Deep faults significantly impact the structural stabilities and deformation behaviors of their overburden rocks, which are key factors in underground engineering and geological hazard research. Considering the problem of deep-fault-overburdened breaking during mining of super-thick coal seams and taking the Yaoqiao Coal Mine as the research object, the mining fracture evolution characteristics and overburden displacement law of the non-structured and fault-bearing overburden corresponding to fully mechanized caving mining are compared and analyzed using numerical simulations and physical similarity simulations. The results of this study show the following: 1) The fracture height of the overlying rock presents a specific change law with advancement of the working face; the initial rapid increase to a maximum height of 74 m is achieved when the working face advances to 90 m; with the development of the plastic zone indicating past yield, the fracture height decreases to 54 m and becomes stable, and the final caving angle of the fracture stabilizes at 70°. 2) In coal mining under normal fault conditions, when the working face advances from the upper to lower walls, the roof forms a masonry beam structure that slows down fault activation and crack development. When moving away from the fault, the overburden movements and water-conducting cracks are fewer, and the crack height is lower than that without faults. When approaching the fault, the influence of the faults in the fracture zone increases, and the height of fracture development reaches the maximum value after crossing the fault, highlighting the significant influence of the fault on fracture development. 3) Through a similarity simulation test, it is shown that the overburden caving zone is further compacted by the overburden rock and that the roof collapses in a large range, resulting in rapid upward development of the overburden rock cracks and separation of the central overburden rock cracks that are gradually compacted and closed. These findings are expected to have important theoretical and practical significance for deep underground engineering design, geological disaster prevention, and fault activity monitoring.

Analysis of Tsunami Characteristics of Korea Southern Coast Using a Hypothetical Scenario

Large-scale earthquakes are occurring globally, especially in the South Asian crust, which is experiencing a state of tension in the aftermath of the 2011 East Japan Earthquake. Uncertainty and fear regarding the possibility of further seismic activity in the near future have been on the rise in the region. The National Disaster Management Research Institute has previously studied and analyzed the overflow characteristics of a tsunami and the rate of flood forecasting through tsunami numerical simulations of the East Sea of South Korea. However, there is currently a significant lack of research on the Southern Coast tsunamis compared to the East Coast. On the Southern Coast, the tidal difference is between 1~4 m, and the impact of the tides is hard to ignore. Therefore, it is necessary to analyze the impact of the tide propagation characteristics on the tsunami. Occurrence regions that may cradle tsunamis that affect the southern coast region are the Ryukyu Island and Nankai Trough, which are active seafloor fault zones. The Southern Coast has not experienced direct damage from tsunamis before, but since the possibility is always present, further research is required to prepare precautionary measures in the face of a potential event. Therefore, this study numerically simulated a hypothetical tsunami scenario that could impact the southern coast of South Korea. In addition, the tidal wave propagation characteristics that emerge at the shore due to tide and tsunami interactions will be analyzed. This study will be used to prepare for tsunamis that might occur on the southern coast through tsunami hazard and risk analysis.

DFIG in Wind Energy Applications with High Order Sliding Mode Observer-based Fault-Tolerant Control Scheme using Sea Gull Optimization

This paper describes a new method for maximizing power extraction from a wind energy conversion system (WECS) by using a doubly fed induction generator (DFIG) that operates below nominal wind speed. To maximize the collected power of a wind turbine (WTG) exposed to actuator failure, a fault-tolerant high-order sliding mode observer (HOSMO) and Seagull Optimization Algorithm with a model predictive controller (MPC) technique is proposed. Evaluate both the real state and the sensor error simultaneously using a higher-order sliding-mode observer. Active fault tolerant controllers are designed to regulate wind turbine rotor speed and power in the presence of actuator defects and uncertainty. With the growing interest in employing wind turbines (WTGs) as the primary generators of electrical energy, fault tolerance has been seen as essential to improving efficiency and reliability. This research focuses on optimal fault-tolerant pitch control, which is used to modify the pitch angle of wind turbine blades in the event of sensor, actuator, and system failures. A Seagull Optimization Algorithm (SOA) is proposed to tune controller parameters to improve the performance of WT. The proposed method has achieved 92% of power tracking performance when compared to existing method.

Landscape modelling of the Yalong River catchment during the uplift of Southeast Tibet

Southeast Tibet is characterized by low-relief surfaces at high-elevation, showing very little exhumation during the India–Asia collision, as well as deeply incised rivers valleys. Understanding how these low-relief surfaces adjacent to the plateau's edge survived from regressive fluvial erosion is still an enigma, which is key to understanding the formation of the plateau. In the Three Rivers Region around the Eastern Himalayan Syntaxis, the squeezing of the Salween, Mekong and Yangtze rivers’ drainage basins in their middlestream, where numerous thrusts parallel to the river channels are observed, has been invoked as the key factor driving the river evolution. More to the east, in the Great Bends Region, no such squeezing of the drainage basins has been observed; the Yalong and Yangtze rivers flow perpendicularly across northeast-trending thrust belts, generating huge (>100 km) river course bends with steep channel slopes. These faults have significantly contributed to construct the high plateau margin, including the Yalong Thrust Belt (YTB), active during the Eocene (∼35–25 Ma) and reactivated in the Miocene (15–12 Ma). By applying state-of-the-art landscape modelling (FastScape) to the Yalong River catchment, with simplified rock uplift scenario deduced from fault activities, we show that strong monsoonal precipitation on the plateau (∼1 m/yr), even during only a short period such as the Mid–Miocene Climatic Optimum (17–14 Ma), produces wide rivers and destroys the plateau edge. In contrast, modelling the orographic effect with weak net precipitation (∼0.2 m/yr) above ∼2700 or 4000 m, preserves the plateau edge and reproduces the slope of the Yalong River, but with a width larger than in nature. To reproduce both the slope and narrowness of the Yalong gorge just upstream of the YTB, a combination of a rapid Miocene rock uplift leading to a regional surface uplift, which creates a significant orographic effect and preserves interfluve low-relief surfaces close to the plateau edge, and a water inflow in upstream, which deeply incises downstream river valleys, is necessary. Such an amount of upstream water is collected from the flat and expansive headwater, inherited from the inland endorheic zone of the plateau interior, on which the hillslope processes dominate the landscape evolution.

Modern endogenous geological processes in the territory of Central Belarus

The article examines the manifestation features of modern endogenous geological processes in the territory of Central Belarus. A scheme of their distribution has been constructed. A comprehensive methodology has been used to study these processes. It includes the analysis of published and fund materials, multi-age geological, geomorphological, topographic maps of different scales, remote sensing data and the results of field and route observations, measurements at geodynamic testing sites, cartometric and cartographic works. It has been established that despite the location of the region in the western part of the Precambrian East European Platform, the processes of modern endogenous geodynamics develop quite diversely and with varying intensity within its boundaries. They are expressed in the activation of linear faults (faults, cosmoand topolineaments), ring structures, vertical and horizontal displacements of the earth’s crust and its shaking (seismicity).

Evolution of submarine canyons and hanging-wall fans: insights from geomorphic experiments and morphodynamic models

Abstract. Tectonics play a significant role in shaping the morphology of submarine canyons, which form essential links in source-to-sink (S2S) systems. It is difficult, however, to investigate the resulting morphodynamics over the long term. For this purpose, we propose a novel experimental approach that can generate submarine canyons and hanging-wall fans on continuously evolving active faults. We utilize morphometric analysis and morphodynamic models to understand the response of these systems to fault slip rate (Vr) and inflow discharge (Q). Our research reveals several key findings. Firstly, the fault slip rate controls the merging speed of submarine canyons and hanging-wall fans, which in turn affects their quantity and spacing. Additionally, the long profile shapes of submarine canyons and hanging-wall fans can be decoupled into a gravity-dominated breaching process and an underflow-dominated diffusion process, which can be described using a constant-slope relationship and a morphodynamic diffusion model, respectively. Furthermore, both experimental and simulated submarine canyon–hanging-wall fan long profiles exhibit strong self-similarity, indicating that the long profiles are scale independent. The Hack's scaling relationship established through morphometric analyses serves as an important link between different scales in S2S systems, bridging laboratory-scale data to field-scale data and submarine-to-terrestrial relationships. Lastly, for deep-water sedimentary systems, we propose an empirical formula to estimate fan volume using canyon length, and the data from 26 worldwide S2S systems utilized for comparison show a strong agreement. Our geomorphic experiments provide a novel perspective for better understanding of the influence of tectonics on deep-water sedimentary processes. The scaling relationships and empirical formulas we have established aim to assist in estimating volume information that is difficult to obtain during long-term landscape evolution processes.

Geomorphic signatures of neotectonic activity along the Western Andean Front in the Chilean Andes (35°S to 37°S)

AbstractCharacterizing neotectonic activity along mountain fronts in active orogens is the key to better understanding trajectories of landscape evolution, climatic‐tectonic couplings and natural hazards. One such prominent mountain front is the Western Andean Front (WAF), which defines the boundary between two main physiographic units along the Chilean Andes (15°S to 39°S): the Central Depression and Principal Cordillera. This study analyses the geomorphic imprints of neotectonic fault activity in the WAF between 35°S and 37°S. We used several topographic metrics, including the mountain‐front sinuosity index (Smf), the valley floor width‐to‐height ratio (Vf) and the stream length‐gradient (SL) index to gain information about the regional distribution of deformation patterns and its relative tectonic activity for distinctive segments. In addition, a raster map combining rock strength (RS) and mean annual precipitation (MAP) allowed discriminating lithology‐climate vs. tectonics influence on SL anomalies from catchments spanning from the main deformation zone to the regional drainage divide. We use the local relief and swath profiles to quantify the incision and transient state of mountain fronts to evaluate the geomorphic response to tectonic and/or climatic input. Our analysis highlights significant variations from north to south, delineating two distinct segments with different topographic, geomorphic and geometric fault characteristics. These segments are indented at approximately 36°S. From north to south, there is a segment with an inactive thrust front with a primarily climate‐driven fluvial response over long timescales and a second segment with a transient state adjusting to relatively high uplift rates. Morphometric data analysis, DEM‐based morpho‐structural maps, geological maps and previous research support the interpretation of two sets of neotectonic faults: (1) NNE‐striking reverse faults with a dextral slip component and (2) NW‐striking sinistral slip faults, likely a response to deformation partitioning caused by oblique subduction on a continental margin.

Spatial-temporal variability of lacustrine evaporite and carbonate deposits: Effects of tectonics and sediment supply

Little attention has been paid to the nonnegligible effects of fault evolution and basin geometry on lacustrine evaporites in faulted basins. In this study, we focused on the Es4 in the Dongying and Zhanhua sags in Bohai Bay Basin and investigated the effects of faults on the spatial–temporal variability of evaporite deposition based on well data, 3D seismic data. Saline lake deposits, such as gypsum and carbonate rocks, were well developed in the Es4 in Dongying sag, but they were developed mainly in the Es4u in Zhanhua sag. Within the Zhanhua sag, the development pattern of saline lake deposits varied in different sub-sags. Carbonate rocks and gypsum rocks developed in the Es4u of the Bonan sub-sag, but they were rarely seen in the Gubei sub-sag. Different from the typical pattern of carbonate rock development in gentle-slope zones, thick layers of carbonate rocks were deposited in steep-slope zones on the footwall block of the boundary fault in the Bonan sub-sag. Fault evolution and combination controlled the geomorphic variations and sediment supply of the basins, thereby determining the salinity of lake water and uneven spatial–temporal distribution of hydrodynamic conditions. In the Dongying sag, the pre-existing faults in the northern basin connected to the new faults to form a large fault zone with great extension distance and strong activity, and the paleo-lake basin in the Dongying sag had a large area and deep water. The pre-existing faults in the Zhanhua sag were locally reactivated and orthogonally intersected with the new faults, forming a multi-center paleo-lake basin with a small area and a relatively shallow water body. The range and distribution of deep-water zones controlled by the scale of the paleo-lake basins affected the variability of gypsum rock development in the Zhanhua and Dongying sags. The range of deep-water zones, their distribution pattern, and sediment supply jointly influenced the variability of gypsum rock development in the Bonan and Gubei sub-sags. The stepped landform developed in the Yinan fault zone and Mg+ and Ca+ from the Paleozoic carbonate strata in the Yidong bulge jointly caused the deposition of ultra-thick carbonate rocks on the footwall block of the Yidong fault during the sedimentation period of the Es4u.Additionally, in terms of the scale of system tracts, the episodic fault activity affected the supply of terrestrial clastics and freshwater by influencing the formation of basin margin fans, thereby controlling the vertical variation of water salinity in the Bonan paleo-lake basin and thus the periodic evolution of the salt lake. The climate cycle was not the main controlling factor.

Multi‐Segment Earthquake Clustering as Inferred From 36Cl Exposure Dating, the Bet Kerem Fault System, Northern Israel

AbstractRecovering the seismic history of multiple segments within a fault system provides a spatiotemporal framework for the fault activity across the system. This kind of data is essential for improving our understanding of how faults interact during earthquake cycles and how they are distributed within a fault system. Bedrock fault scarps, reaching up to 10‐m height, are abundant across the Bet Kerem fault system, Galilee, northern Israel. Using the 36Cl exposure dating method, we recovered the last 30 ka scarp exhumation history of three fault segments from the Bet Kerem fault system. Results indicate that the three faults were active simultaneously in at least three distinguished activity periods, during which a minimum of 1.2 m of surface rupturing occurred in each period. The synchronized activity and total surface rupture at each activity period suggest that the three dated segments were ruptured simultaneously by the same earthquake. That is, a multi‐segment rupture earthquake and that each activity period included a cluster of at least two large multi‐segment earthquakes. The results also indicate a recurrence interval between clusters of 3.5–4.5 ka and the existence of a seismic super cycle with a recurrence interval of about 13 ka.

Reduction of Subsidence and Large-Scale Rebound in the Beijing Plain after Anthropogenic Water Transfer and Ecological Recharge of Groundwater: Evidence from Long Time-Series Satellites InSAR

Beijing, China’s capital city, has experienced decades of severe land subsidence due to the long-term overexploitation of groundwater. The implementation of the South-to-North Water Diversion Project (SNWDP) and artificial ecological restoration have significantly changed Beijing’s hydro-ecological and geological environment in recent years, leading to a widespread rise in groundwater levels. However, whether the related land subsidence has slowed down or reversed under these measures has not yet been effectively monitored and quantitatively analyzed in terms of time and space. Accordingly, in this study, we proposed using an improved time-series deformation method, which combines persistent scatterers and distributed scatterers, to process Sentinel-1 images from 2015 to 2022 in the Beijing Plain region. We performed a geospatial analysis to gain a better understanding of how the new hydrological conditions changed the pattern of deformation on the Beijing Plain. The results indicated that our combined PS and DS method provided more measurements both in total quantity and spatial density than conventional PSI methods. The land subsidence in the Beijing Plain area has been effectively alleviated from a subsidence region of approximately 1377 km2 in 2015 to only approximately 78 km2 in 2022. Ecological restoration areas in the northeastern part of the Plain have even rebounded over this period, at a maximum of approximately 40 mm in 2022. The overall pattern of ground deformation (subsidence and uplift) is negatively correlated with changes in the groundwater table (decline and rise). Local deformation is controlled by the thickness of the compressible layer and an active fault. The year 2015, when anthropogenic water transfers were eliminated and ecological measures to recharge groundwater were implemented, was the crucial turning point of the change in the deformation trend in the subsidence history of Beijing. Our findings carry significance, not only for China, but also for other areas where large-scale groundwater extractions are causing severe ground subsidence or rebound.

Repeated and Long‐Lasting Fault Activation on Amazonian Mars as Demonstrated by Tectonically Induced Landslides

AbstractWe identify and analyze a large shortening structure (surface expression of a thrust fault) in western Arabia Terra, Mars, exhibiting recent, repeated, and long‐lasting tectonic activity. Where the fault system deforms Marsabit crater rim, four landslides with differing degradation states extend onto the crater floor. We propose these were triggered by episodic re‐activation of the thrust system. Using a morphological map and crater size frequency statistics we show that the fault system experienced at least four landslide‐inducing events during the Middle to Late Amazonian. We note that 1.4 km total displacement on the fault plane must have required many events to accumulate if motion was by brittle failure rather than continuous creep. The current understanding of tectonic activity and stress‐sources since 3.6 Ga, cannot account for these repeated and large Amazonian marsquakes—suggesting revaluation of sources of stress to account for a more active and complex Amazonian tectonic history.

Comparison of Performance Analysis Results with Developed Site-Specific Response Spectra and Turkish Seismic Design Code: A Case Study from the SW Türkiye Region

On 6 February 2023, the Kahramanmaraş earthquakes clearly showed that the elastic spectrum curves in TBEC-2018 are insufficient to represent earthquake behavior. In this study, the effect of using a site-specific spectrum curve instead of the elastic spectrum given in TBEC-2018 on the earthquake safety of a building is investigated. For this purpose, the provinces in southwest Anatolia, Türkiye, which is one of the most tectonically complex regions with frequent seismic events, were selected. In the first stage of the study, spectrum curves were obtained for earthquakes with return periods of 2475, 475, and 72 years for each of the provinces in this region. These spectrum curves were obtained using probabilistic seismic hazard studies that take into account the active faults of the provinces and earthquake activity in both historical and instrumental periods. In the second stage of the study, analytical models of a selected model RC building were created according to each province, and static pushover analyses of these building models were performed both according to the elastic spectrum given in TBEC-2018 and according to the spectrum curve created specifically for the province. The results of the analyses show that the change in the spectrum changes the target displacement level of the buildings, and as a result, the cross-sectional damage zone of the structural elements under the earthquake effect is changed. So much so that using the site-specific instead of the elastic spectrum given in TBEC-2018 changed the damage zone of 43% of the beams and 26.4% of the columns in the İzmir model. The change in the section damage zones changed the performance level of some floors of the models and the performance level of the building. The study revealed the importance of using the most realistic elastic spectrum curves in order to determine the earthquake performance of buildings that is as close as possible to their behavior in a possible earthquake.