scholarly journals The 2021 Mw 6.7 Khankh earthquake in the Khuvsgul rift, Mongolia

2021 ◽  
Vol 26 (52) ◽  
pp. 46-61
Author(s):  
Davaasambuu Battogtokh ◽  
Amgalan Bayasgalan ◽  
Kang Wang ◽  
Davaasuren Ganzorig ◽  
Jargalsaikhan Bayaraa

A Mw 6.7 occurred at Lake Khuvsgul in northwestern Mongolia at 05:32:56 AM Ulaanbaatar time on the 12th of January 2021. The epicenter of the event was offshore south of the Doloon Uul peninsula around 30 km SSW of Khankh village. Shaking was felt within most of central and western Mongolia, including the capital city Ulaanbaatar ~600 km from the epicenter. The earthquake appears to have ruptured the Khuvsgul fault along the western coast of Lake Khuvsgul. The earthquake is the largest in Mongolia since the Mw 6.3 Busiin Gol earthquake in 1991. Our research team from the Institute of Astronomy and Geophysics, Mongolian Academy of Sciences visited the epicenter area for 5 days soon after the earthquake and installed four broad-band seismic stations and searched the area for geological evidence of the earthquake. The location, azimuth, dip and depth of this earthquake defined by moment tensor solutions calculated by the international seismological centers and analysis of InSAR interferograms and field observations. The projected intersections of the east-dipping nodal planes with the surface for solutions of the international seismological centers and researchers correlate relatively well with the mapped strike and location of the old tectonic scarp of the Khuvsgul fault although we have not discovered any primary co-seismic surface rupture. The InSAR interferogram demonstrates the sharp discontinuity and fringes in the area between the Western Range and Doloon Uul peninsula which implies surface deformation. Aftershocks that have continued during the three months subsequent to the earthquake define overall strike of the mainshock rupture.

2020 ◽  
Vol 324 (2) ◽  
pp. 262-272
Author(s):  
I.V. Doronin ◽  
T.N. Dujsebayeva ◽  
K.M. Akhmedenov ◽  
A.G. Bakiev ◽  
K.N. Plakhov

The article specifies the type locality of the Steppe Ribbon Racer. The holotype Coluber (Taphrometopon) lineolatus Brandt, 1838 is stored in the reptile collection of the Zoological Institute of the Russian Academy of Sciences (ZISP No 2042). Literature sources provide different information about the type locality. A mistake has been made in the title of the work with the original species description: the western coast of the sea was indicated instead of the eastern one. The place of capture was indicated as “M. Caspium” (Caspian Sea) on the label and in the reptile inventory book of the Zoological Museum of the Academy of Sciences. The specimen was sent to the museum by G.S. Karelin. The “1842” indicated on the labels and in the inventory book cannot be the year of capture of the type specimen, just as the “1837” indicated by A.M. Nikolsky. In 1837, Karelin was in Saint Petersburg and in 1842 in Siberia. Most likely, 1837 is the year when the collection arrived at the Museum, and 1842 is the year when the information about the specimen was recorded in the inventory book (catalog) of the Zoological Museum of the Academy of Sciences. In our opinion, the holotype was caught in 1932. From Karelin’s travel notes of the expedition to the Caspian Sea in 1832, follows that the snake was recorded in two regions adjacent to the eastern coast of the Caspian Sea – Ungoza Mountain (“Mangyshlak Mountains”) and site of the Western Chink of Ustyurt between Zhamanairakty and Kyzyltas Mountains (inclusive) on the northeast coast of Kaydak Sor (“Misty Mountains”). In our article, Karelin’s route to the northeastern coast of the Caspian Sea in 1832 and photographs of these localities are given. The type locality of Psammophis lineolatus (Brandt, 1838) should be restricted to the Mangystau Region of the Kazakhstan: Ungoza Mountain south of Sarytash Gulf, Mangystau (Mangyshlak) Penninsula (44°26´ N, 51°12´ E).


Geosciences ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 408 ◽  
Author(s):  
King ◽  
Quigley ◽  
Clark

We digitize surface rupture maps and compile observational data from 67 publications on ten of eleven historical, surface-rupturing earthquakes in Australia in order to analyze the prevailing characteristics of surface ruptures and other environmental effects in this crystalline basement-dominated intraplate environment. The studied earthquakes occurred between 1968 and 2018, and range in moment magnitude (Mw) from 4.7 to 6.6. All earthquakes involved co-seismic reverse faulting (with varying amounts of strike-slip) on single or multiple (1–6) discrete faults of ≥ 1 km length that are distinguished by orientation and kinematic criteria. Nine of ten earthquakes have surface-rupturing fault orientations that align with prevailing linear anomalies in geophysical (gravity and magnetic) data and bedrock structure (foliations and/or quartz veins and/or intrusive boundaries and/or pre-existing faults), indicating strong control of inherited crustal structure on contemporary faulting. Rupture kinematics are consistent with horizontal shortening driven by regional trajectories of horizontal compressive stress. The lack of precision in seismological data prohibits the assessment of whether surface ruptures project to hypocentral locations via contiguous, planar principal slip zones or whether rupture segmentation occurs between seismogenic depths and the surface. Rupture centroids of 1–4 km in depth indicate predominantly shallow seismic moment release. No studied earthquakes have unambiguous geological evidence for preceding surface-rupturing earthquakes on the same faults and five earthquakes contain evidence of absence of preceding ruptures since the late Pleistocene, collectively highlighting the challenge of using mapped active faults to predict future seismic hazards. Estimated maximum fault slip rates are 0.2–9.1 m Myr-1 with at least one order of uncertainty. New estimates for rupture length, fault dip, and coseismic net slip can be used to improve future iterations of earthquake magnitude—source size—displacement scaling equations. Observed environmental effects include primary surface rupture, secondary fracture/cracks, fissures, rock falls, ground-water anomalies, vegetation damage, sand-blows / liquefaction, displaced rock fragments, and holes from collapsible soil failure, at maximum estimated epicentral distances ranging from 0 to ~250 km. ESI-07 intensity-scale estimates range by ± 3 classes in each earthquake, depending on the effect considered. Comparing Mw-ESI relationships across geologically diverse environments is a fruitful avenue for future research.


2021 ◽  
Author(s):  
Johan Fourdrinoy ◽  
Julien Dambrine ◽  
Madalina Petcu ◽  
Morgan Pierre ◽  
Germain Rousseaux

<p>While seeking to revisit an old experiment of John Scott Russell, we discovered a new mechanism for generating a non-shoaling bolus (an ovoid coherent mass of recirculating mixed fluids immerged in a surrounding medium/a of different density/ies) propagating along a pycnocline. In a study about dead-water (Fourdrinoy et al. 2020), a wave resistance phenomenon induced by internal waves formation at the interface between waters of different densities, we modified the setup used by Scott Russell. The Scottish engineer studied the formation and propagation of dispersive waves when an object is removed from a laterally confined open channel with a shallow layer of water. The “vacuum” created by the mass removal generates a linear dispersive free surface deformation with a front of negative polarity followed by a wave train. If we extend this configuration to a two-layers stratification, we can observe a linear dispersive wave with negative polarity à la Scott Russell, propagating along the interface. In addition, the removal of the object generates under certain conditions a bolus which induces a mixing zone and a gradient transition layer. We will present this new method of boluses creation, as well as an experimental characterization with space-time diagrams thanks to a subpixel detection procedure.</p><p>The dual nature of the dead-water phenomenology: Nansen versus Ekman wave-making drags.<br>Johan Fourdrinoy, Julien Dambrine, Madalina Petcu, Morgan Pierre and Germain Rousseaux.<br>Proceedings of the National Academy of Sciences, Volume 117, Issue 29, p. 16739-16742, July 2020.</p>


2021 ◽  
Vol 49 (3) ◽  
pp. 12-32

A brief overview of the main historical events that accompanied the formation and establishment of the Laboratory of Oceanology in the Academy of Sciences in 1941 is given. Then, a few years later, the Laboratory was transformed into the Institute of Oceanology, the director of which was appointed the Minister of the Merchant Fleet of the USSR, Academician P. P. Shirshov. By his initiative in 1949, the Institute became the owner of its first large research vessel "Vityaz". It is shown that the entire history of the institute and its research team was primarily based on the development and generalization of the results of regular sea and ocean expeditions. The article provides general information about the results obtained in the recent past, and their development and deepening in the works of the institute at present.


2020 ◽  
Vol 11 (2019/2) ◽  
Author(s):  
Ákos Bertalan Apatóczky

The late Professor Louis Ligeti was one of the most influential scholars of the 20th century in the fields of Altaic historical linguistics and many others. Ligeti’s personal scholarly notes, according to the provisions of his will, were deposited in the Library of the Hungarian Academy of Sciences (HAS) and were not released for 40 years. In 2018 a special research team of the HAS of Linguistics and Literary Scholarship Section was established to process the contents of the more than 70 large cardboard boxes. This study introduces a segment of his notes on deciphering the Khitan language, dealing with numerals, and offers insights into the current opinion of scholars whenever it varies from Ligeti’s. Minor corrections to the readings of Khitan ‘one’ as well as to the name of the ‘Old(er) Khitan State’ are also suggested.


2019 ◽  
Vol 110 (1) ◽  
pp. 49-66 ◽  
Author(s):  
Kristofer T. Hornsby ◽  
Ashley R. Streig ◽  
Scott E. K. Bennett ◽  
Jefferson C. Chang ◽  
Shannon Mahan

ABSTRACT The Meers fault (Oklahoma) is one of few seismogenic structures with evidence for Holocene surface rupture in the stable continental region of North America. The 37-kilometer-long southeast section of the full 54-kilometer-long Meers fault is interpreted to be Holocene active. The 17-kilometer-long northwest section is considered Quaternary active, but not Holocene active. We reevaluate surface expression and earthquake timing of the northwest Meers fault to improve seismic source characterization. We use airborne light detection and ranging and historical stereopaired aerial photos to evaluate the fault scarp and local fault-zone geomorphology. In the northwest, complex surface deformation includes fault splays, subtle monoclinal warping, and a minor change in fault strike. We interpret that the along-strike transition from surface faulting on the southeast Meers fault to surface folding on the northwest Meers fault occurs at the lithologic contact between Permian Post Oak conglomerate and Hennessey shale. We excavated a paleoseismic trench to evaluate the timing of surface-deforming earthquakes on the northwest section of the fault. The excavation revealed weathered Permian Hennessey shale and an ∼1–2-meter-thick veneer of Holocene alluvial deposits that were progressively deformed during two surface-folding earthquakes likely related to blind fault rupture beneath the site. Repeated onlapping to overlapping stratigraphic sequences and associated unconformities are intimately related to folding events along the monocline. OxCal paleoearthquake age modeling indicates that earthquakes occurred 4704–3109 yr B.P. and 5955–4744 yr B.P., and that part of the northwest section of the Meers fault is Holocene active. We find the Holocene-active section of the Meers fault should be lengthened 6.1 km to the northwest, to a total Holocene-active fault length of 43 km. Empirical scaling relationships between surface rupture length and magnitude reveal that the fault could generate an Mw 7.0 earthquake.


2016 ◽  
Vol 47 (3) ◽  
pp. 1308
Author(s):  
N. Triantafyllis ◽  
E. Sokos ◽  
A. Ilias

Modern seismic networks with broadband sensors and real time digital telemetry made Moment Tensor (MT) determination a routine procedure. Automatic MT’s are now provided by global networks and a few very dense regional networks, within minutes after a significant event. An automatic MT determination wasn’t possible for the broader Hellenic area since seismic station density wasn’t sufficient. The creation of the Hellenic Unified Seismic Network (HUSN) provided the opportunity to apply an automated MT procedure using the available broad band data from almost    one hundred stations. Thus the ISOLA code was extended towards the automatic operation based on Linux OS shell scripts, stand alone Fortran codes and SAC2000. Software supports both manual and automatic mode; at the first case, the user manually runs the program with the desired input parameters while at the latter, the system monitors a mailbox or RSS feed and if it receives an appropriate notification triggers the MT inversion procedure based on certain conditions. As it is setup now it calculates automatically the moment tensor of earthquakes larger than 3.5M  w using data from HUSN. Application of an automated MT inversion procedure for HUSN will provide important real time information for studies like ground motion evaluation, tsunami warning etc.


2015 ◽  
Vol 58 (4) ◽  
Author(s):  
Claudio Ferrari ◽  
Maurizio Bonafede ◽  
Elisa Trasatti

Pressurized cavities are commonly used to compute ground deformation in volcanic areas: the set of available solutions is limited and in some cases the moment tensors inferred from inversion of geodetic data cannot be associated with any of the available models. Two different source models (pure tensile source, TS and mixed tensile/shear source, MS) are studied using a boundary element approach for rectangular dislocations buried in a homogeneous elastic medium employing a new C/C++ code which provides a new implementation of the dc3d Okada fortran code. Pressurized triaxial cavities are obtained assigning the overpressure in the middle of each boundary element distributed over the cavity surface. The MS model shows a moment domain very similar to triaxial ellipsoidal cavities. The TS and MS models are also compared in terms of the total volume increment limiting the analysis to cubic sources: the observed discrepancy (~10%) is interpreted in terms of the different deformation of the source interior which provides significantly different internal contributions (~30%). Comparing the MS model with a Mogi source with the some volume, the overpressure of the latter must be ~37% greater than the former, in order to obtain the same surface deformation; however the outward expansion and the inner contraction separately differ by ~±10% and the total volume increments differ only by ~2%. Thus, the density estimations for the intrusion extracted from the MS model and the Mogi model are nearly identical.


1994 ◽  
Vol 37 (6) ◽  
Author(s):  
A. Mendez ◽  
F. Pacor

The Irpinia project, as carried out by ISMES under a commission from ENEL, had as objectives the developement of a general methodology to simulate broad-band seismic ground motion at near-source and regional distances, and the application of this methodology to the 1980 Irpinia earthquake. Within this general framework, one goal was the comparison of four previously published models for this earthquake in order to arrive at a plausible description of the source process. The comparative study was cast as an inverse problem: that of inferring the spatial extent and temporal behaviour of the rupture process, from geodetic measurements of surface deformation and near-source recordings of ground velocity. This study was complicated by the fact th the Irpinia earthquake was a complex event, involving at least three distinct rupture episodes in a time span of 40 s. However, this same complexity offers the opportunity of illustrating the use of inversion methodologies to 1) infer the spatial slip distribution on a multiple fault system; 2) address the problem of determining the accuracy of the inferred slip models, and 3) use information describing the static characteristics of an earthquakes as an aid in understanding the kinematics of the rupture. This last point is illustrated for the 40 s subevent through the results of a forward modeling study of high-frequency acceleration waveforms using a rupture model based on the inversion results.


2020 ◽  
Author(s):  
S.G. Batyreva

Статья посвящена сравнительному анализу орнаментального декора войлока и ткани ойратов Западной Монголии и калмыков России на материале экспонатов Музея традиционной культуры им. Зая-пандиты Калмыцкого НЦ РАН и других отечественных музеев. Автор использует методы исторической науки, этнологии и искусствознания, применяемые в музеологии. В ходе исследования рассмотрены узоры, украшавшие предметы традиционного быта калмыков описаны типичные приемы их орнаментальной отделки, формы узоров, цветовые и композиционные решения выявлены связи орнаментики с традиционным миропониманием номадов изучена калмыцкая техника вышивки-аппликации зег установлено, что стеганый узор войлока ойратов и калмыков это квинтэссенция художественной традиции номадов. Все это позволяет сделать вывод о генетической взаимосвязи калмыцкой вышивки и узорного войлока, прослеживаемой в геометрическом узоре зег своеобразной трансформации стеганого узора войлока. При этом становится очевидным, что орнаментальный декор войлока сохраняет традиционный код культуры, являющийся художественным наследием номадов.The article is devoted to a comparative analysis of the ornamental decor of felt and fabric of the Oirats of Western Mongolia and the Kalmyks of Russia based on the exhibits of the Zaya-Pandita Museum of Traditional Culture of the Kalmyk Scientific Center of the Russian Academy of Sciences with the involvement of collections of other museums in Russia. The interdisciplinary study of artistic traditions uses the methods of history, ethnology and art studies used in museology. The author reveals the significance of felt in the culture of nomadic peoples and describes the ornaments used to symbolically designate world space, natural phenomena, and seasons. An analogy is traced between the Kalmyk signs of property and the symbolic writing of the Mongolian peoples. The patterns decorating the objects of traditional life of the Kalmyk people are considered: felt mats, panels, blankets. At the same time, typical techniques of ornamental decoration of these products, the most common forms of patterns are identified and described, color and compositional solutions are characterized, and ornaments are connected with the traditional worldview of nomads. The loss of significance of the tradition of felting among the Kalmyks at the turn of the 20th century is noted. Further development of this industry among the Oirats of Mongolia is considered up to the beginning of the 21st century. The examples of the decor of womens clothing items from Hoboksar (Xinjiang Uygur Autonomous Region, PRC) revealed the unity of the ornamental tradition of the Oirats, which applies not only to felt, but also to fabric. The corresponding parallel is drawn with respect to the Kalmyk cloth pouches. The general motifs of the ornamental design of the carpets of the Noin-Ula nomads (end of the 1st century BC 1st century AD) and Kalmyk felt mats are revealed. The Kalmyk technique of application zeg is considered and described, its significance is established as the formative basis of the folk arts and crafts of Kalmykia. It is established that the geometric quilted pattern of felt of the Oirats and the Kalmyks is a concentrate of the nomadic artistic tradition. Kalmyk embroidery and patterned felt in the initial basis of stitches are genetically interconnected by the geometric pattern zeg, which is a transformation of the quilted pattern of felt. The embroidered decor of the Kalmyk costume compensates for the lost position of the artistic metal that prevails in the aesthetics of the Oirat folk costume. Patterned felt, the original material of Kalmyk life, and its ornamental decor preserve the traditional cultural code, transmitted as the artistic heritage of the nomads.


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