A Phenomenological Model of Orientational Magnetic Anisotropy of Sediments     

Andrei A. Kosterov  Vladimir A. Shashkanov 《Geophysical Journal International》1996,125(1):149-162

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Geometry of the fault zone of the 2003 Ms = 7.5 Chuya earthquake and associated stress fields, Gorny Altai     

Oxana V. Lunina  Andrei S. Gladkov  Igor S. Novikov  Anna R. Agatova  Evgenii M. Vysotskii  Alexei A. Emanov 《Tectonophysics》2008,453(1-4):276

The co-seismic deformations produced during the September 27, 2003 Chuya earthquake (Ms = 7.5) that affected the Gorny Altai, Russia, are described and discussed along a 30 km long segment. The co-seismic deformations have manifested themselves both in unconsolidated sediments as R- and R′-shears, extension fractures and contraction structures, and in bedrock as the reactivation of preexisting schistosity zones and individual fractures, as well as development of new ruptures and coarse crushing zones. It has been established that the pattern of earthquake ruptures represents a typical fault zone trending NW–SE with a width reaching 4–5 km and a dextral strike–slip kinematics. The initial stress field that produced the whole structural pattern of co-seismic deformations during the Chuya earthquake, is associated with a transcurrent regime with a NNW–SSE, almost N–S, trending of compressional stress axis (σ₁), and a ENE–WSW, almost E–W, trending of tensional stress axis (σ₃). The state of stress in the newly-formed fault zone is relatively uniform. The local stress variations are expressed in insignificant deviation of σ₁ from N–S to NW–SE or NE–SW, in short-term fluctuations of relative stress values in keeping their spatial orientations, or in a local increase of the plunge angle of the σ₁. The geometry of the fault zone associated with the Chuya earthquake has been compared with the mechanical model of fracturing in large continental fault zones with dextral strike–slip kinematics. It is apparent that the observed fracture pattern corresponds to the late disjunctive stage of faulting when the master fault is not fully developed but its segments are already clearly defined. It has been shown that fracturing in widely different rocks follows the common laws of the deformation of solid bodies, even close to the Earth surface, and with high rates of movements.  相似文献   

Flood hazard and risk assessment in Russia     

Shalikovskiy  Andrei  Kurganovich  Konstantin 《Natural Hazards》2016,83(1):133-153

The occurrence of rockfall incidents on the transportation network may cause injuries, and even casualties, as well as severe damage to infrastructure such as dwellings, railways, road corridors, etc. Passive protective measures (i.e., rockfall barriers, wire nets, etc.) are mainly deployed by operators of ground transport networks to minimize the impact of detrimental effects on these networks. In conjunction with these passive measures, active rockfall monitoring should ideally include the magnitude of each rockfall, its initial and final position, and the triggering mechanism that might have caused its detachment from the slope. In this work, the operational principle of a low-cost rockfall monitoring and alerting system is being presented. The system integrates measurements from a multi-channel seismograph and commercial cameras as the primary equipment for event detection. A series of algorithms analyze these measurements independently in order to reduce alarms originated by surrounding noise and sources other than rockfall events. The detection methodology employs two different sets of algorithms: Time–frequency analyses of the rockfall event’s seismic signature are performed using moving window pattern recognition algorithms, whereas image processing techniques are utilized to deliver object detection and localization. Training and validation of the proposed approach was performed through field tests that involved manually induced rockfall events and recording of sources (i.e., passing car, walking people) that may cause a false alarm. These validation tests revealed that the seismic monitoring algorithms produce a 4.17 % false alarm rate with an accuracy of 93 %. Finally, the results of a 34-day operational monitoring period are presented and the ability of the imaging system to identify and exclude false alarms is discussed. The entire processing cycle is 10–15 s. Thus, it can be considered as a near real-time system for early warning of rockfall events.  相似文献   

Characterization of natural hydrocarbon seepage in the South Caspian Sea off Iran using satellite SAR and geological data     

Andrei Yu. Ivanov  Hadi Gerivani  Natalia V. Evtushenko 《Marine Georesources & Geotechnology》2020,38(5):527-538

Abstract

Two groups of oil slicks have been repeatedly detected in the Southern Caspian Sea, off Cape Sefidrud and close to the Iranian coast of the sea on the synthetic aperture radar (SAR) images acquired by the Sentinel-1A and Sentinel-1B satellites in April–June 2018. Analysis of the SAR images together with bathymetry, geological and geophysical data in geographic information system showed that these manifestations (oil slicks) visible on the sea surface have natural origin, related to the bottom seepage phenomenon and are associated with existing hydrocarbon system. Oil slicks are concentrated over the continental slope and related to local geological formations of the sedimentary cover having oil deposits related to paleo-delta of Sefidrud River. Our evidence shows that two seeps in this area are active and repeating. It is concluded that the SAR is an excellent tool for monitoring of seepage phenomenon. Moreover, results indicate that the use of remote methods to identify offshore natural oil seeps related to existing active petroleum system can be considered as a well-accepted approach to support oil and gas exploration in frontier areas such as the South Caspian Basin.  相似文献   

Geodynamics and Regularities of Seismicity in the Eastern Segment of the Amurian Plate     

A. A. Stepashko  T. V. Merkulova  A. N. Didenko 《Russian Journal of Pacific Geology》2018,12(4):263-277

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Fluvial and permafrost history of the lower Lena River,north-eastern Siberia,over late Quaternary time     

Georg Schwamborn  Lutz Schirrmeister  Ali Mohammadi  Hanno Meyer  Andrei Kartoziia  Flavio Maggioni  Jens Strauss 《Sedimentology》2023,70(1):235-258

Arctic warming and permafrost thaw visibly expose changes in the landscape of the Lena River delta, the largest Arctic delta. Determining the past and modern river regime of thick deltaic deposits shaping the Lena River mouth in north-eastern Siberia is critical for understanding the history of delta formation and carbon sequestration. Using a 65 m long sediment core from the delta apex a set of sedimentological techniques is applied to aid in reconstructing the Lena River history. The analysis includes: (i) grain-size measurements and the determination of the bedload composition; (ii) X-ray fluorescence, X-ray diffractometry, and magnetic susceptibility measurements and heavy mineral analysis for tracking mineral change; (iii) pH, electrical conductivity, ionic concentrations, and the δ¹⁸O and δD stable isotope composition from ground ice for reconstructing permafrost formation. In addition; (iv) total and dissolved organic carbon is assessed. Chronology is based on; (vi) radiocarbon dating of organic material (accelerator mass spectrometry and conventional) and is complemented by two infrared – optically stimulated luminescence dates. The record stretches back approximately to Marine Isotope Stage 7. It holds periods from traction, over saltation, to suspension load sedimentation. Minerogenic signals do not indicate provenance change over time. They rather reflect the change from high energy to a lower energy regime after Last Glacial Maximum time parallel to the fining-up grain-size trend. A prominent minimum in the ground ice stable isotope record at early Holocene highlights that a river arm migration and an associated refreeze of the underlying river talik has altered the isotopic composition at that time. Fluvial re-routing might be explained by internal dynamics in the Lena River lowland or due to a tectonic movement, since the study area is placed in a zone of seismic activity. At the southern Laptev Sea margin, onshore continental compressional patterns are bordering offshore extensional normal faults.  相似文献   

An object-oriented information model for territorial system management     

Andrei A. Kaganovich  Sergei P. Prisyazhnyuk  Andrei S. Prisyazhnyuk 《GeoJournal》2018,83(6):1331-1337

This article examines an object-oriented geospatial information model for territorial system management, its benefits compared to current automated territorial management systems, and special aspects of its development and implementation in multi-level geoinformation systems. The presented study reflects the major functions of geoinformation materials used in spatial planning, particularly in Earth remote sensing. A territorial information management model is developed from the perspective of the object-oriented geoinformation approach. The study identifies the major functions of the proposed management system and demonstrates what kinds of problems can be solved using this system, develops a spatial algorithmic model for managerial decision-making and a methodology for analyzing local territorial system characteristics; and introduces basic information arrays that can be used to solve practical territorial management problems at various levels.  相似文献   

Modeling and cyclic behavior of segmental bridge column connected with shape memory alloy bars   总被引：1，自引：1，他引：0  

Hwasung Roh  Andrei M.Reinhorn  Jong Seh Lee 《地震工程与工程振动(英文版)》2012,11(3):375-389

This paper examines the quasi-static cyclic behavior,lateral strength and equivalent damping capacities of a system of post-tensioned segmental bridge columns tied with large diameter martensitic Shape Memory Alloy(SMA) link-bars.Moment-curvature constitutive relationships are formulated and analysis tools are developed for the PT column,including a modified four-spring model prepared for the SMA bars.The suggested system is exemplified using a column with an aspect ratio of 7.5 and twelve 36.5 mm diameter NiTi martensitic SMA bars.A post-tensioning force of 40% to 60% of the tendon yield strength is applied in order to obtain a self re-centering system,considering the residual stress of the martensitic SMA bars.The cyclic response results show that the lateral strength remains consistently around 10% of the total vertical load and the equivalent viscous damping ratios reach 10%-12% of critical.When large diameter NiTi superelastic SMA bars are incorporated into the column system,the cyclic response varies substantially.The creep behavior of the superelastic SMA bar is accounted for since it affects the re-centering capability of the column.Two examples are presented to emphasize the modeling sensitivities for these special bars and quantify their cyclic behavior effects within the column assembly.  相似文献   

Stress states of thawed soil subgrade     

Andrei Petriaev 《寒旱区科学》2015,7(4):348-353

The article presents the field measurement results of the stress states of roadbed thawed soil subgrade during the passage of trains. The dependences of the vertical and horizontal stresses on the velocity of the rolling stock motion, the axle load, and the distance from the sleeper sole have been obtained.  相似文献   

Survey of Geomagnetic Observations Made in the Northern Sector of Russia and New Methods for Analysing Them     

Alexei Gvishiani  Renata Lukianova  Anatoly Soloviev  Andrei Khokhlov 《Surveys in Geophysics》2014,35(5):1123-1154

An overview of the geomagnetic observations made in the northern part of Russia is presented from a historical perspective. Several stations were deployed on the territory of the former Soviet Union during the International Geophysical Year, 1957–1958, with the active participation and guidance of the Interagency Geophysical Committee which is inherited by the Geophysical Center of the Russian Academy of Sciences (GC RAS). In the 1990s, the majority of these stations, especially those in the remoter regions, were closed. Nowadays, the geomagnetic network, including the observatories of the INTERMAGNET program, has been restored. Examples of high-latitude geomagnetic variations in the Russian longitudinal sector are shown, and maps and trends of the secular variation over the territory of Russia presented. Particular attention is paid to the automated processing of data and to the analysis methods used. To process the growing amount of high-resolution geomagnetic data, sophisticated mathematical methods based on the fuzzy logic approach and new discrete mathematical analysis algorithms have been developed. The formal methods and algorithms for recognizing both artificial and natural disturbances in the magnetograms are described.  相似文献