Fault Junction Research Articles

Forty years spatio-temporal seismicity distribution and the evidences of the pore pressure impact on triggering earthquakes at the northern part of Lake Nasser, Aswan, Egypt

This study has examined the spatial and temporal distribution of seismicity recorded by Aswan seismic local network distributed around the northern part of the Lake Nasser in operation continuously for 40 years (1982–2021). This investigation shows that most of the seismicity is clustered on the Kalabsha fault and its follow up small segments. The seismicity also clustered in the Khor El-Raml area and in the junction of Seiyal fault with Kurkur faults to the North of the Kalabsha fault. The direction of the spatial distribution of the earthquakes in this study shows N–S direction. The temporal major unit is set as one year and the minor unit is set as one day. This study reveals that the accumulation and release of the energy are probably alternated between these active zones. The seismic quiescence has been detected in the Khor El-Raml and in the junction of Seiyal and Kurkur faults since 2007, also the seismic quiescence has been detected in both eastern and western parts of Kalabsha fault since 2015. Therefor, it can be expected a remarkable seismic activity in the near future in one of these active areas. The evidences of the impact of the water infiltration from the lake in triggering earthquakes have been detected in the Abu Dirwa fault, Khor El-Raml area, in the junction of Seiyal and Kurkur faults and in the Spillway fault area. In this study, also the relationship between the earthquakes and the groundwater level of the four piezometer wells in the Seiyal and Spillway fault areas have been examined. Unfortunately, we have not got a clear relation between the groundwater level and the seismicity due to the low seismicity in the Seiyal and Spillway areas during the short operation period of these wells.

Termination of the Ganderian Cambrian–Ordovician Miramichi terrane in east-central Maine, northern Appalachian orogen, USA

The Ganderian Cambrian–Ordovician Miramichi terrane narrows in east-central Maine and terminates at the junction of faults that separate it from the mostly Silurian Central Maine/Aroostook–Matapedia basin (CMAM) to the northwest and Fredericton trough to the southeast. The terrane was emergent after Middle Ordovician recumbent folding and shed sediment to both adjacent depocenters. Its boundary faults are the youngest deformation events and play important roles in its termination, but do not by themselves explain it. The presence of distinctive CMAM strata southeast of the northwest boundary fault indicates that the first step in developing the current relationships was an episode of hitherto unrecognized late Silurian eastward thrusting. In the northern (Danforth) segment of the terrane, intermediate facies CMAM strata were thrust onto their Miramichi source rocks. The thrust sheet was deformed by Acadian upright folds, then dissected by dip-slip offset along boundary and internal faults prior to intrusion of the 409 ± 2 Ma Skiff Lake pluton. Subsequent erosion isolated a remnant of the thrust sheet as the Dill Hill klippe, its allochthonous CMAM strata isolated among Miramichi rocks. The southern (Greenfield) segment experienced similar events, but current relationships are different and timing of the late-stage faults is not well constrained. Allochthonous CMAM strata may have overridden the Miramichi terrane completely, so that a remnant of distinctive CMAM strata is now exposed east of the Miramichi terrane in fault contact with rocks of the Fredericton trough. The entire Greenfield segment is interpreted as a fault block exposed within the thrust sheet.

Age and Tectonic Setting of the Kopri-Type Granitoids at the Junction Zone of the Dzhugdzhur–Stanovoi and Western Stanovoi Superterranes of the Central Asian Fold Belt

Geochemical, geochronological (U–Pb on zircons, ID TIMS), and isotope–geochemical (Sm–Nd) studies of Kopri-type granitoids of the Tukuringra Complex have been carried out. The granitoids are located exclusively in the zone of the Dzheltulak suture, which separates the Dzhugdzhur–Stanovoi and Western Stanovoi superterranes of the Central Asian fold belt. It has been established that they can be classified as postcollisional adakite-like granitoids of elevated alkalinity and adakite-type basicity, formed in the age range between 127 ± 1 and 126 ± 1 Ma, which are part of the Late Mesozoic postcollisional Stanovoi volcano-plutonic belt that extends more than 1000 km in the sublatitudinal direction from the Sea of Okhotsk into the continent subparallel to the Mongolia–Okhotsk suture zone and stitches the Dzhugdzhur–Stanovoi and the Western Stanovoi superterranes. The structural position of the Kopri-type granitoid massifs registers the upper age limit of the Dzheltulak suture. Formation of the parent melts of these granitoids is associated with an essentially lithospheric source formed as a result of mixing of the Early Precambrian and a younger, apparently Phanerozoic component. In contrast to other granitoids of the Stanovoi belt that are close in composition and age, the granitoids under consideration are characterized by a certain increase in the role of the asthenospheric component in their source, which is probably due to their localization in the zone of elevated lithospheric permeability and at the junction of faults of different orientations, generally sublatitudinal, guided by the Mongolia–Okhotsk lineament, and northwestward, associated with the development of the Dzheltulak suture.

Eastward expansion of the Tibetan plateau: Insights from stress drops of the 2021 Ms 6.4 Yangbi, Yunnan and Ms 7.4 Maduo, Qinghai earthquake sequences in China

The eastward expansion of the Tibetan Plateau has resulted in extensive seismic activities in the eastern Tibetan Plateau, along with various types of faulting processes across this region. However, the crustal stress status related to these phenomena remains unclear. On 21 May 2021, the Ms 6.4 Yangbi and Ms 7.4 Maduo earthquakes with diverse focal mechanisms occurred consecutively in the Chuandian and Bayan Har blocks in the southern and northern parts of the eastern Tibetan Plateau, providing a distinct opportunity to directly compare the stresses in both flanks of the laterally expanding plateau. In this study, we estimate the stress drops of the Yangbi and Maduo earthquake sequences for all M≥3.0 events from the Lg-wave spectra. Both the path attenuation and site effect are properly removed based on an established broadband Lg-wave attenuation model. Then, the distribution of the stress drops is refined through high-precision earthquake relocation. Quick decays in stress drops were observed after both mainshocks. The Yangbi sequence has a relatively high median stress drop value, with significantly high stress drops for some foreshocks that possibly indicate a cascade triggering mechanism for the nucleation of the mainshock. In comparison, the Maduo sequence is characterized by a higher stress drop for the mainshock and sustained large fluctuation in stress drops for aftershocks. The Maduo aftershocks extend both the eastern and western directions from the mainshock, with relatively low stress drops in the east, suggesting a large amount of energy has been spent to drive the supershear rupture during the mainshock. We also find that the stress drops are associated with fault junctions for the Yangbi sequence, and are associated with variations in strength along the fault for the Maduo sequence, which are very likely linked with patterns of crustal motion and deformation in the eastern Tibetan Plateau.

Coseismic and early postseismic deformation of the 2020 Nima Mw 6.4 earthquake, central Tibet, from InSAR and GNSS observations

The 2020 Mw6.4 Nima earthquake is one of the largest normal-faulting earthquakes recently occurring north of the Banggong suture zone in remote central Tibet, where geologic investigation of active faults is extremely limited. We analyze jointly InSAR and GNSS observations over 9 months after the Nima earthquake and calculate the coseismic and postseismic displacement. The optimal coseismic slip model suggests this event is the result of moderate-angle down-dip slip on a complex reversed “S-shape” three-segmented structure at fault junctions of the West Yibu-Chaka fault, the Heishi fault, and an unmapped blind fault, with a small component of left-lateral slip. The superposition of seismic waves from faults with different strikes and dips accounted for a large non-double-couple component in the long-period point-source solutions. The geodetic moment released by the mainshock is 6.4 × 1018 N⋅m, equivalent to Mw 6.42. Coseismic rupture concentrated at a depth of 4–15 km, with a peak slip of 1.36 m at 8.5 km depth. The cumulative afterslip moment within 9 months after the mainshock is 1 × 1018 N m, about 15.6% of that released by the mainshock coseismic slip. The afterslips contributed largely to the release of additional strain energy. In addition, shallow creep on the northern part of the blind fault, and deep uplift on the east normal fault system are promoted by stress perturbations. A significant proportion of down-dip coseismic slip spreading to more than 20 km beneath the surface, and deep up-slip afterslip have implications for the rheology of down-dip extension of the dipping faults in northern Tibet. Two obvious stress loading zones of more than 1 bar highlight seismic hazards in the region, especially in the junction between normal faults and ends of the large-size sinistral Riganpei-Co and Jiangai-Zangbu faults. It is necessary to forecast accurately by longer-term afterslip observation over timescales of years for the faults. Compared with previous studies, our results suggest a more complex subsurface fault geometry linking the normal and strike-slip faults and dynamic stress adjustment in this poorly-known region of Tibet.

Shortening Rates and Recurrence of Large Earthquakes From Folded and Uplifted Terraces in the Western Danghe Nan Shan Foreland, North Tibet

AbstractUnderstanding the three‐dimensional structure, segmentation, and kinematics of complex fault systems is essential to assessing the size of potential earthquakes and related seismic hazards. The Danghe Nan Shan thrust, a major splay of the Altyn Tagh fault (ATF) in north Tibet, is one of these complex fault junctions. Near the town of Subei, the western Danghe Nan Shan thrust composes two left‐stepping faults outlined by fault scarps in front of folded and uplifted alluvial fans and terraces. Age constraints and 2D reconstructions of the accumulated slip above a transient base level of four terraces standing 7–60 m above the present stream bed yield shortening and vertical uplift rates of 0.5 ± 0.1 and 1.1 ± 0.3 mm/yr, respectively, over the last 130 ka on the southern thrust. Along the northern thrust, vertical terrace offsets of 1.5–3.6 m and horizontal slip of 4.5 m documented in a paleoseismological trench occurred after 12 ± 4 ka, constraining coeval rates of 0.3 ± 0.1 mm/yr for uplift and shortening. Overall, 1.4 ± 0.4 mm/yr terrace uplift and 0.8 ± 0.2 mm/yr shortening rates are determined, in agreement with late Miocene long‐term exhumation rate estimates. Our fault mapping and geomorphic and structural observations imply that the western Danghe Nan Shan thrust accommodates slip transfer from the ATF to the west to thrusting and shortening farther east in the Qilian Shan region. Considering the scarp sizes, their lateral extent, the geometry of the faults at depth, and their slip‐rate, we suggest the possible occurrence of Mw 7+ earthquakes near Subei.

Tectonic evolution of the Indio Hills segment of the San Andreas fault in southern California, southwestern USA

Abstract. Transpressional uplift domains of inverted Pliocene–Pleistocene basin fill along the San Andreas fault zone in Coachella Valley, southern California (USA), are characterized by fault linkage and segmentation and deformation partitioning. The Indio Hills wedge-shaped uplift block is located in between two boundary fault strands, the Indio Hills fault to the northeast and the main San Andreas fault to the southwest, which merge to the southeast. Uplift commenced about or later than 0.76 million years ago and involved progressive fold and faulting stages caused by a change from distributed strain to partly partitioned right-slip and reverse/thrust displacement on the bounding faults when approaching the fault junction. Major fold structures in the study area include oblique, right-stepping, partly overturned en echelon macro-folds that tighten and bend into parallelism with the Indio Hills fault to the east and become more open towards the main San Andreas fault to the west, indicating an early and close relationship of the macro-folds with the Indio Hills fault and a late initiation of the main San Andreas fault. Sets of strike-slip to reverse step-over and right- and left-lateral cross faults and conjugate kink bands affect the entire uplifted area, and locally offset the en echelon macro-folds. Comparison with the Mecca Hills and Durmid Hills uplifts farther southeast along strike in Coachella Valley reveals notable similarities, but also differences in fault architectures, spatial and temporal evolution, and deformation mechanisms. The present work contributes to better understand the structure and tectonic history of a major fault system along a transform plate boundary.

Laterally Varying Crustal and Quaternary Fault-Zone Structures in the Seoul Metropolitan Area, South Korea, from a Joint Inversion Analysis Based on Dense Seismic Arrays

ABSTRACTThe crustal structure and Quaternary fault zone in the Seoul metropolitan area are investigated using a joint inversion that combines the receiver functions with surface wave dispersion based on seismic data from densely deployed seismic arrays. The uncertainty in inverted models is examined through a set of synthetic experiments. Synthetic tests and comparisons with other methods verify the observed crustal features. The Moho depths range between 28.7 and 32.8 km with relatively shallow depths in the central Seoul metropolitan area. The VP/VS ratio varies between 1.67 and 1.85. A Conrad discontinuity with a weak velocity increase is present at a depth of ∼20 km. Low-velocity anomalies appear at depths of ∼3 km and 6–11 km along the Chugaryeong fault zone and fault junction area. Apparent shear wave velocity contrasts appear across the fault zone where earthquakes are clustered. A high-velocity block in the western Seoul metropolitan area lies along the fault zone that runs across western Seoul. The shear wave velocity models and seismicity suggest that the fault zone may extend to a depth of 11 km at least.

Large‐Scale Interseismic Strain Mapping of the NE Tibetan Plateau From Sentinel‐1 Interferometry

AbstractThe launches of the Sentinel‐1 synthetic aperture radar satellites in 2014 and 2016 started a new era of high‐resolution velocity and strain rate mapping for the continents. However, multiple challenges exist in tying independently processed velocity data sets to a common reference frame and producing high‐resolution strain rate fields. We analyze Sentinel‐1 data acquired between 2014 and 2019 over the northeast Tibetan Plateau, and develop new methods to derive east and vertical velocities with ∼100 m resolution and ∼1 mm/yr accuracy across an area of 440,000 km2. By implementing a new method of combining horizontal gradients of filtered east and interpolated north velocities, we derive the first ∼1 km resolution strain rate field for this tectonically active region. The strain rate fields show concentrated shear strain along the Haiyuan and East Kunlun Faults, and local contractional strain on fault junctions, within the Qilianshan thrusts, and around the Longyangxia Reservoir. The Laohushan‐Jingtai creeping section of the Haiyuan Fault is highlighted in our data set by extremely rapid strain rates. Strain across unknown portions of the Haiyuan Fault system, including shear on the eastern extension of the Dabanshan Fault and contraction at the western flank of the Quwushan, highlight unmapped tectonic structures. In addition to the uplift across most of the lowlands, the vertical velocities also contain climatic, hydrological or anthropogenic‐related deformation signals. We demonstrate the enhanced view of large‐scale active tectonic processes provided by high‐resolution velocities and strain rates derived from Sentinel‐1 data and highlight associated wide‐ranging research applications.

Microseismicity along Xiaojiang Fault Zone (Southeastern Tibetan Plateau) and the characterization of interseismic fault behavior

The Xiaojiang Fault (XJF) Zone locates in the southeastern of Tibetan Plateau and defines the boundary between the South China and Sichuan-Yunnan blocks. Historical large earthquakes were hosted on the XJF, though its seismic hazard in the near future is under debate. In this study, we utilize portable broad-band seismic network to unravel the microseismic activities along XJF, and to further investigate the fault structures and their properties. Adopting PALM, a newly developed earthquake detection algorithm, we obtained ~13,000 relocated events. The micro-seismicity reveals widespread off-fault structures showing conjugate geometry, while the major faults present low seismicity. The fault branches conjugate to the main-fault present intensive microseismicity, which hosts repeating events and presents high b-value. Regional GPS stations reflect slips are mostly concentrated along the XJF, while the slip rate on off-fault branches correlates with seismic activities on these structures. Combining with other recent seismological and magnetotellurics evidences, we suggest a low strength on these off-fault structures, which may partially release tectonic stress loading and serve as a barrier for future big earthquakes. On the XJF, the microseismic events are clustered on the fault junctions with low b-value. A special set of clusters between 25°N to 25.5°N show an along-strike variation of depth from 10 to 25-km, imaging the boundary between creeping and locked fault portions. We revisit the seismic hazard problem of XJF, and conclude that XJF is at the late stage of inter-seismic period.

Deep fault slip characteristics in the Xianshuihe-Anninghe-Daliangshan Fault junction region (eastern Tibet) revealed by repeating micro-earthquakes

• 9 repeating earthquake sequences are identified in the Xianshuihe-Anninghe-Daliangshan Fault junction region in eastern Tibet . • The southern Xianshuihe Fault and the Gongyihai section of Daliangshan Fault is creeping, while the southern Anninghe Fault is locked. • The accumulated strain on the southern Anninghe Fault is large enough to form the next M7 earthquake. The Xianshuihe-Anninghe-Daliangshan Fault junction region in eastern Tibet marks the transition zone between the creeping Xianshuihe Fault and the locked Anninghe Fault. However, the role in slip partitioning of these three faults is unclear, mainly because the geodetic data lack the resolution to discriminate slip at depth. Repeating earthquakes, the seismic events rupture the same fault patch more than once, are recognized as the slip meters at depth and play an important role in the assessment of seismic hazard. In this study, repeating earthquakes in the Xianshuihe-Anninghe-Daliangshan Fault junction region are identified and the deep fault slip characteristics are investigated. First, a complete catalog (2013–2020) for the study region is achieved by using Matched Filter Technique detecting the continuous waveforms of the dense Xichang array. Second, waveform cross-correlation and double-difference location technologies are used to identify repeating earthquakes. Finally, by checking waveforms, focal depth and satellite images, mining expositions are excluded and 9 repeating earthquake sequences (RES) are obtained. RES indicate the deep slip at a rate of 8 mm/yr on the southern Xianshuihe Fault is partitioned to the northern Anninghe Fault and the Gongyihai section of Daliangshan Fault at rates of 1 mm/yr and 2–6 mm/yr, respectively. Aseismic slip on the southern Xianshuihe Fault and northern Anninghe Fault reach to 12 km depth. A large asperity on the Anninghe Fault from Liziping to Xichang is constrained by the back ground seismicity and the location of RES, which will form a M ∼ 7 potential earthquake when it ruptures.

Faulted landforms, slip-rate, and tectonic implications of the eastern Lenglongling fault, northeastern Tibetan Plateau

The Lenglongling fault (LLLF) is an important part of the Qilian-Haiyuan fault (QHF) zone along the NE Tibetan Plateau. The Jinqianghe fault (JQHF) branches off of the LLLF and forms a fault junction that separates middle and eastern LLLF. Currently, it is not well understood how/if strain from the LLLF is transmitted to the JQHF over geologic time scales and how seismically active the eastern section of the LLLF is. Recent studies indicate that the 1927 M8 Gulang earthquake ruptured the middle LLLF and propagated eastward onto the eastern LLLF instead of propagating onto the JQHF. To assess if this concurrent rupture of middle and eastern LLLF is (or might be) a common phenomenon, we measured the Holocene slip-rate at the Huoshaotai site, east of the LLLF – JQHF junction, to compare it with known rates from the middle LLLF. Using displaced geomorphic markers and radiocarbon dating, we determined a Holocene left-lateral slip-rate of 6.0 ± 0.8 mm/a for the eastern LLLF. This rate is only slightly below the consensus slip-rate for the middle LLLF (6.6 ± 0.3 mm/a; 6.4 ± 0.7 mm/a), suggesting a gradual strain transfer and similar seismic activity for both sections. Paleoseismic evidence further suggests that at least three preceding earthquakes may have ruptured both sections simultaneously during the Holocene, indicating that concurrent failure of both sections, as in 1927, may not be uncommon. Concurrent failure of middle LLLF and JQHF is however not reported. Hence, it appears that LLLF and JQHF act as independent seismo-tectonic entities, without substantial strain transfer or concurrent seismic activity. These observations contribute to a better understanding of the QHF zone and the potential for multi-fault rupture along it.

Joint earthquake ruptures of the San Andreas and San Jacinto faults, California, USA

Abstract Large, multi-fault earthquakes increase the threat of strong ground shaking and reshape the probability of future events across a system of faults. Fault junctions act as conditional barriers, or earthquake gates, that stop most earthquakes but permit junction-spanning events when stress conditions are favorable. Constraining the physical conditions that favor multi-fault earthquakes requires information on the frequency of isolated events versus events that activate faults through the junction. Measuring this frequency is challenging because dating uncertainties limit correlation of paleoseismic events at different faults, requiring a direct approach to measuring rupture through an earthquake gate. We show through documentation and finite-element modeling of secondary fault slip that co-rupture of the San Andreas and San Jacinto faults (California, USA) through the Cajon Pass earthquake gate occurred at least three times in the past 2000 yr, most recently in the historic 1812 CE earthquake. Our models show that gate-breaching events taper steeply and halt abruptly as they transfer slip between faults. Comparison to independent chronologies shows that 20%–23% of earthquakes on the San Andreas and the San Jacinto faults are co-ruptures through Cajon Pass.

Three-Dimensional Surface Deformation Characteristics Based on Time Series InSAR and GPS Technologies in Beijing, China

Excessive exploitation of the groundwater has resulted in obvious three-dimensional (3D) deformation features on the surface of the Beijing Plain. This paper, by combining Interferometric Synthetic Aperture Radar (InSAR) and Global Positioning System (GPS) technologies, has obtained time-series information of the 3D surface deformation in the Beijing Plain, analyzing its spatial distribution characteristics. On this basis, the relationship between different controlling factors with the 3D deformation of the surface has been analyzed as well. The following results are obtained: (1) From 2013 to 2018, the land subsidence, which generally showed the trend of slowing down, was mainly concentrated in the eastern, northern, and southern regions of Beijing Plain, with multiple subsidence centers. (2) Under the International Terrestrial Reference Frame 2005 (ITRF2005), the horizontal direction of all GPS points in the plain is basically the same, with the dominant movement direction being NE112.5°~NE113.8°. Under the Eurasian reference frame, the horizontal movement rate of GPS points significantly decreases. The movement rate and direction of each point are not characteristic of overall trend activity. (3) The distribution and extent of the 3D surface deformation in the Beijing Plain are controlled by the basement structure. Part of the subsided area corresponds to a Quaternary depression formed at the junction of active faults disrupting the area. Similarly, the distribution of horizontal deformation in the E-W and N-S directions of the plain is controlled by the regional basement structure comprising major faults bounding horizontal deformation. (4) Groundwater exploitation is the main cause of the 3D surface deformation in the Beijing Plain. The groundwater funnels of the second and third confined aquifer are in suitable agreement with the land subsidence. The horizontal movement in the Beijing Plain is either directed toward the center of the groundwater or the land subsidence funnel, and the deformation is directed from areas with higher to areas with lower groundwater levels.

Geo-ecological features of the transformation of the natural environment (a case study of oil and gas field development in the Chechen Republic)

The article analyses the transformation of the natural environment of the Chechen Republic resulting from the development of oil and gas fields. The Chechen Republic has physical and geographical features that are reflected in the complex differentiation of its mountainous landscapes, associated with the location of the territory at the junction of various tectonic formations and faults. The authors mapped the main areas of oil and gas fields, varying in terms of the development of the oil and gas complex and its impact on landscapes. The results of field studies with a sampling of soil, water, plant ash and bottom sediments assess the ecological-geochemical situation that has developed in the republic, and Grozny in particular, over recent decades.

The 2019 Ridgecrest, California earthquake sequence: Evolution of seismic and aseismic slip on an orthogonal fault system

Cascade-up and/or slow-slip processes are commonly believed to control interactions between foreshocks, mainshocks and aftershocks, but their relative contributions remain poorly resolved. Discrimination between these processes will shed light on the understanding of earthquake physics, which requires exceptional observations of earthquake sequences. The well-recorded July 2019 Ridgecrest, California foreshock-mainshock-aftershock earthquake sequence provides such an opportunity. We perform simultaneous inversion of the July 4th MW 6.4 foreshock and July 5th MW 7.1 mainshock kinematic rupture models using SAR, strong motion, and GPS data. We also invert for afterslip models following the MW 6.4 foreshock and the mainshock, respectively, by developing an inversion method that utilizes strainmeter, SAR and daily GPS time series. The inversion results show that the overall sequence involves no less than six fault segments, which include a main northwest-trending fault and secondary faults with sub-parallel and orthogonal geometry to the main fault. Co-seismic slip and afterslip have complementary patterns on the faults. During the early post-seismic period following the MW 6.4 foreshock and the mainshock, moment release on the southwest-trending fault is dominated by aseismic slip, in contrast to the predominantly seismic slip on the northwest-trending fault. The mainshock appears to be triggered by a cascade migration of foreshocks on a northwest-trending fault. Slip on the southwest-trending fault migrates from the fault junction at the northeast end (following the MW 6.4 foreshock) to the southwest end (following the mainshock) during the afterslip interval. The dual-mode (seismic versus aseismic) slip phenomena appear to be driven by co-seismic stress changes produced by the major events.

Seismic and Geodetic Analysis of Rupture Characteristics of the 2020 Mw 6.5 Monte Cristo Range, Nevada, Earthquake

ABSTRACT The largest earthquake since 1954 to strike the state of Nevada, United States, ruptured on 15 May 2020 along the Monte Cristo range of west-central Nevada. The Mw 6.5 event involved predominantly left-lateral strike-slip faulting with minor normal components on three aligned east–west-trending faults that vary in strike by 23°. The kinematic rupture process is determined by joint inversion of Global Navigation Satellite Systems displacements, Interferometric Synthetic Aperture Radar (InSAR) data, regional strong motions, and teleseismic P and SH waves, with the three-fault geometry being constrained by InSAR surface deformation observations, surface ruptures, and relocated aftershock distributions. The average rupture velocity is 1.5 km/s, with a peak slip of ∼1.6 m and a ∼20 s rupture duration. The seismic moment is 6.9×1018 N·m. Complex surface deformation is observed near the fault junction, with a deep near-vertical fault and a southeast-dipping fault at shallow depth on the western segment, along which normal-faulting aftershocks are observed. There is a shallow slip deficit in the Nevada ruptures, probably due to the immature fault system. The causative faults had not been previously identified and are located near the transition from the Walker Lane belt to the Basin and Range province. The east–west geometry of the system is consistent with the eastward extension of the Mina Deflection of the Walker Lane north of the White Mountains.

Hydrotermal mineralization hosted by Cambrian sedimentary rocks asevidence of kimberlite-hosting structure, Syuldyukarskoye field, Yakutia

The paper describes diamondiferous kimberlite area within a new Yakutian Syuldyukarskoye fi ld and presents detailed mapping results of ore-hosting shear evidence, veinlet bleaching of redbeds, outcrops of metagrained pyrite, pyrite-calcite and calcite veinlets hosted by Cambrian terrigenous-carbonate rocks where kimberlites occur. Kimberlite localization is shown at fault junction as well as kimberlite long axis combination with west-northwest orehosting shear. These tectonic structures combine with veinlet bleaching halos, those of pyrite-calcite and calcite veinlets, and calcite druses characterized by red photoluminescence and phosphorescence. Red, blue and partially white photoluminescence is caused by manganese concentration in calcites (> 0,1%). Hydrothermal calcite nature is supported by C and O isotope composition variations, which reflect the input of medium temperature formational and meteoric waters, carbon of sedimentary carbonate rocks and deep hydrocarbons. Anomalous Ba, Cr, Ni and La content is recognized in hydrothermal calcites from near-kimberlite environment. Kimberlite position in the southeastern part of endogenous mineralization halos and greater diamond potential of the western kimberlite body, which is larger compared to the eastern one, allow forecasting of new productive bodies.

Substantiation of parameters of mine working drivage with blasting technique and cleaning charges in advance cutting holes

Drilling and blasting operations (D&B) are the most difficult and laborious operations in the process of mineral extraction, requiring permanent development and upgrading of methods and equipment. The aim of the study is to substantiate the parameters of drilling and blasting drivage of horizontal and inclined (up to 12o) mine workings on the basis of high-performance self-propelled equipment and new designs of box cuts with cleaning explosive charges (0.2 kg of 6ZhV ammonite), placed in advance holes of 65 to 105 mm in diameter. The paper presents the results of the analysis of practical experience and scientific achievements in the field of drilling-andblasting rupture of solid media and continuum mechanics. The need for new designs of box cuts, reliability of which in the formation of high-quality (clean) cut cavity reaches 0.95-1.00, was substantiated. New design options of box cuts have been developed, the peculiarity of which consists in provision of sufficient compensation (peripheral) volume with the use of blast hole cut charges for blasting rupture of trapezoidal partitions, with the compensation volume factor of 2.50 to 1.34. Promising areas of research were shown using the example of complicated structure ore deposits and large faults in the Kirovograd ore district and crystalline rocks of the Ukrainian shield at the following mines of Ukraine: PJSC KZhRK, CJSC Sukhaya Balka (Kryvyi Rih), Vostok-Ruda LLC, SE VostGOK (Zheltye Vody), CJSC ZZhRK, etc. Promising areas of research were proposed using the example of complicated structure ore deposits typically formed at the junction of large faults; besides, the use of environmentally friendly emulsion explosives and self-propelled emulsion explosive chargers was recommended.

First Results and Prospects of a New Approach to the Study of Active Geologic Processes by Space and Ground Instrumental Measurements (by the Example of Kamchatka and the Central Asian Orogenic Belt)

Abstract ––The use of satellite-geological information permits generalization of studies of various active geologic processes in a new way. As reference examples, we consider geologic regions extensively covered by research with our contribution. The joint use of satellite images, maps of gravity anomalies, and seismic-tomography data for Kamchatka made it possible to construct 3D models of surficial and deep-seated (depths from 10–50 to 650 km) volcanic structures. For young volcanosedimentary structures of Kamchatka, it is possible to trace the interaction of various processes, from crystallization of magmas in magma chambers to ore and oil formation in calderas. Ancient tectonic structures and superposed Cenozoic deformations in the Tien Shan, Altai, and Baikal regions are clearly displayed in satellite images and on maps of gravity anomalies. The long-range impact of the Indo-Eurasian collision on the Tien Shan, Altai, and Baikal regions was expressed as shearing, which resulted in the most contrasting structures in the zones of junction of regional faults and along the framing of cratonal structures. The active structures of Gorny Altai contain numerous travertines, whose abundance is correlated with seismic activity. The mass formation of methane and gas hydrates in Lake Baikal might be related to mantle plume fluids.