岫岩MS5.4地震前后S波分裂研究

利用辽宁数字地震台网的营口台的三分向数字化地震资料,研究了1999年岫岩Ms5.4地震前后S波分裂特征.结果表明:(1)延迟时间大部分在0.9～7.2ms/km范围内,平均4.23ms/km;(2)震前快S波的优势偏振方向为N51°～88°E,平均N58.66°E;震后S波的偏振方向主要集中在N1°W～N2°E和N55°～84°E范围内,平均偏振角为近NS向和N68.13°E.NE的偏振方向与震源应力场的主压应力方向N70°E接近,由此推测1999年岫岩Ms5.4地震的S波分裂是震源应力场引起的介质各向异性的结果.     

2000年云南姚安Ms6.5地震余震序列S波分裂研究

本文利用云南姚安MS6 5地震后在震中附近架设的 3个三分向数字记录台站的地震资料 ,对该区S波分裂进行研究。结果表明 :① 2 36条处于横波窗内的记录S波分裂现象明显 ;②延迟时间大部份在 3 5～ 10 5ms km范围 ,平均值为 7 0ms km ;③快波偏振方向大部份在N140°E～N16 4°E范围 ,平均值为N15 2 4°E ;④快波的优势偏振方向与主震的发震断裂 (马尾菁断裂 )和余震的发震破裂方向不一致 ,而与该区的主压应力方向比较符合 ;⑤姚安地震余震序列的S波分裂是应力场控制的EDA裂隙各向异性的结果。     

安庆4.8级地震的余震S波分裂研究

利用安徽数字地震台网安庆台记录的地震波形资料,运行Matlap S波分裂程序,对2011年1月19日安徽安庆4.8级地震的余震序列开展S波分裂研究。结果表明,快S波偏振方向有两个优势取向,分别为N73°E和N94°E,初步判断为区域应力场导致的EDA裂隙系各向异性结果。其中快S波N73°E偏振方向与区域应力场的主压应力方向N74°E基本相同,而快S波N94°E偏振方向稍有偏差,可能是由于4.8级主震产生的应力扰动引起的。慢S波延迟时间在0.82～10.92范围内变化,平均为2.84,主震后,延迟时间明显下降,可能反映了震后应力的释放过程,而几次较大余震前则处于上升高值状态,可能反映了较大余震前的应力积累过程。     

武定6.5级地震序列震源机制

由地震Ｐ波初动符号资料，求解得到１９９５年１０月２４日武定６．５级地震序主震及２１外强余震的震源机制解。主震的两个节面走向分别为北西西向，倾向ＮＮＥ，倾角７０°；另一个节面走向为北北东，倾向Ｗ，倾角７７°；等效释放应力场主压力力方位为３２４°，仰角２４°。表明与区域应力场基本一致的主要震震源应力场及发震断裂控制着整个序列的地震活动。     

2013年芦山MS7.0地震序列S波分裂特征

本文测定了2013年4月20日芦山M_S7.0地震震源区及其附近台站的S波分裂参数,包括快波偏振方向和慢波延迟时间,最终得到了40个台站的S波分裂结果．结果显示:在地震主破裂区内观测到的快波优势取向为NE向,与余震分布的长轴方向一致;位于双石—大川断裂以西台站的快波偏振优势方向为NW向,与区域最大主压应力轴方向一致;位于荥经断裂附近台站的快波偏振优势方向为NW向,与该断裂走向一致．快波偏振优势方向随时间的变化结果显示:主震前位于地震破裂区附近的TQU和BAX台站的快波偏振优势方向均呈NE向;主震后TQU台站的快波偏振优势方向为近EW向,而BAX台站的快波偏振优势方向则不突出,反映出芦山地震主震前快波偏振方向受控于龙门山断裂带,而主震后受构造应力场的作用更加明显．此外,各台站的慢波延迟时间为1.25—5.40ms/km,在余震覆盖密集区域,台站的慢波延迟时间均大于3.0ms/km,反映出震源区的各向异性程度较强．芦山主震后,各台站的延迟时间随时间变化持续减小,反映出震源区地壳应力随余震活动逐渐减小．      

2000年1月15日姚安6.5级地震的震源断层与震源应力场

用姚安地震序列前震、主震和余震的 78个震源机制解 ,分析了序列震源断层和震源应力场特征。结果表明 ,姚安地震序列的主破裂面是走向N5 0°W、倾角陡立的构造断裂 ,主震、前震和绝大多数余震都发生在主破裂面上。此外 ,NNE NE向构造断裂在序列发展过程中也参与了活动。序列震源应力场以SSE方位、接近水平的主压应力为主 ,与区域构造应力场一致。在序列发展中 ,震源区应力场出现多方位和多作用方式共存的复杂状态 ,震源破裂出现多方向和多表现形式的复杂性特征     

汶川地震余震序列的地震各向异性

利用2008年5月12日汶川地震震源区及周边地震台站记录的余震序列资料,使用剪切波分裂系统分析法,分析了汶川地震发震构造龙门山断裂带及周边地区的地壳各向异性特征,推断了地壳最大主压应力方向及空间分布特征.研究结果表明：大致以安县为界,位于龙门山北东段的台站快剪切波的偏振方向为北东向,与断裂带走向一致;而位于龙门山西南段的台站快剪切波的偏振方向为北西向,与断裂带走向垂直;这个特征同样揭示出龙门山断裂带西南段逆冲、北东段带有明显走滑性质的特征.研究还显示,靠近龙门山与鲜水河、安宁河小江断裂交汇区附近的台站快剪切波的偏振方向表现比较离散,这可能是由震源区局部的复杂地质构造引起,与该地区复杂的主压应力方向特点一致.     

2017年九寨沟MS7.0地震震源区横波分裂变化特征

对2017年九寨沟M_S7.0地震序列的横波分裂的时空变化特征进行了分析.通过横波窗内S波质点运动图的分析,从九寨沟地震震源区各个地震台站的近震横波记录中提取了横波分裂的快波偏振方向和慢波延迟时间.观测结果显示,震源区各台站的上地壳各向异性在空间上存在分区特征,时间上有随时间的趋势性变化特征.空间上,位于震源区北部余震区内的3个台站中,发震断层东面的台站L5112和L5111只有一个突出的快波偏振优势方向（NNE向）,而西面的L6202台有两个快波偏振优势方向（除了NNE向,还有一个近EW向）,体现了余震区剧烈调整的地壳应力和构造复杂断裂的综合作用;余震区外的3个台站中,震源区东部靠近塔藏断裂（东）附近的JZG台的快波偏振优势方向为NW向,与塔藏断裂（东）的走向一致,南部的台站L5110和L5113的快波偏振优势方向为近EW向,与区域主压应力方向一致;余震区内各台站的平均慢波延迟时间大于余震区外各台站,反映了九寨沟地震孕育过程中余震区的应力积累强于其周边区域.时间上,快波偏振方向在主震后前期离散度较大,随着时间的推移,离散度在后期有逐渐变小的趋势;慢波延迟时间在主震后较大,但随着时间的推移,也表现出逐渐减小,趋于稳定.横波分裂随时间逐渐减小和趋于稳定的变化特征反映了九寨沟地震在孕震中积累的应力,随着主震和余震的发生而导致的应力释放和调整,应力大小和调整幅度逐渐减小,后期趋于稳定.     

2008年汶川地震震源区横波分裂的变化特征

对2008年汶川地震序列的横波分裂的时空变化现象进行了研究．通过在横波窗内S波质点运动图的分析,从地震余震区附近台站的近场地震记录中提取了S波分裂的快波偏振方向和快慢波之间的时间延迟．龙门山断裂附近7个台站的S波分裂的结果显示了快波偏振方向的空间分布特征,断裂带东南侧（四川盆地一侧）台站的快波偏振方向总体为北东方向,而在断裂西北侧高原内部的PWU（平武台）则为近东西方向．观测到了快慢波之间到时差的趋势性变化,靠近余震带南端的L5501台的到时差在主震后持续减小,北端PWU台的到时差比主震前明显增大．横波分裂现象主要由台站下方岩层中随应力场方向排列的微裂隙控制,结果显示了主震和余震过程中区域应力场的变化,汶川地震余震活动带南部的应力在主震和余震中得到了释放,地壳应力场在余震带北部集中,导致了PWU台在主震后介质各向异性强度的增强．     

青藏高原东北缘中上地壳介质各向异性及其构造意义

青藏高原东北缘(94°E—105°E,32°N-40°N)是高原北东向扩张的前沿地带,亦是研究高原生长过程的重要区域.本文利用青海省数字地震台网(2008-2014年)共7年的地震目录和波形数据,首先使用双差定位获取精定位震源位置,在此基础上,挑选位于S波窗口内(射线入射角≤45°)的地震事件,依据S波分裂分析方法(SAM),获取研究区域内共26个台站的S波分裂参数.研究结果表明:地处多个块体交汇部位的西宁及其周缘,地壳各向异性呈现两个优势偏振方向,表明该区中上地壳应力环境由区域主压应力场和活动断层共同约束;玉树地震序列的地壳各向异性优势偏振方向与区域主压应力场一致.     

琼中地震台重力仪记录同震响应特征分析

2013年2月6-8日圣克鲁斯群岛发生6次强震,琼中地震台的重力仪记录都有同震响应出现。本文从重力仪记录的面波的延迟时间、最大变形幅度、同震持续时间3个方面研究了6次强震的同震响应特征。     

On the Mechanism of the Secular Tidal Acceleration of the Solid Inner Core and the Viscosity of the Liquid Core

As is known, the secular deceleration of the Earth's diurnal rotation is explained mainly by the tidal friction in the ocean. Below we consider this mechanism in some detail, taking into account also elastic deformations of the mantle under the action of ocean loading and the interaction between the tide-generating body, ocean tidal wave, liquid outer core, and solid inner core. It is shown that elastic displacements of the core-mantle boundary under the action of ocean loading are of about the same amplitude and phase as the elastic loading displacements of the Earth's outer surface. As a result, side by side with the mechanism of secular deceleration of diurnal rotation of the mantle, there are also (1) the opposite mechanism of secular acceleration of diurnal rotation of the outer liquid core and of the solid inner core and (2) the mechanism of excitation of differential rotation in the liquid core. Taking these effects into account, we compare theoretical and modern observed data on the eastward drift of the solid inner core. It is shown that the best agreement may be obtained if the turbulent viscosity of the liquid core is about 2 × 10 ³ Poise     

Comparison Between the Nutations of the Planet Mars and the Nutations of the Earth

The nutations of the planets Mars andEarth are investigated and compared. Alarge number of interior structureparameters are involved in the nutationcomputations. The comparison between the observations and the computationsprovides several constraints on these parmeters andtherefore allows a better understanding of the physics of the interior of theplanet. For the Earth, the high precision of the observations of the nutationshas led to a very good determination of interior properties of the planet. ForMars, observations of nutations are not yet available, and we review how theamplitude of the Martian nutations depends on the hypotheses consideredfor its interior. Although Mars is very similar to the Earth, its interior is not well known;for example, we don't knowif its core is liquid or solid. Only if the core is liquid,the Free Core Nutation (FCN) normal mode exists and can alter the nutationswhich are close to the resonance. From the observed geoids, it is known thatboth planets are not in hydrostatic equilibrium. The departure is larger forMars than for the Earth, and consequently, the implication of considering a convective mantle instead of a mantle in hydrostatic equilibrium described byClairaut's equation for the initial equilibrium state of the planet is largeron the Martian nutations than on the Earth nutations. The consequences of theuncertainty in the core dimensions are also examined and shown to be of a veryhigh influence for Mars if the core is liquid, due to the potential changes inthe FCN resonance. The influence of the presence of an inner core, which isknown to exist for the Earth, could be more important for Mars than for theEarth if the inner core is large. Due to the presence of Tharsis on Mars, thetriaxiality of this planet has, additionally, larger effects than on Earth.     

Contribution to the knowledge of the magmatic evolution by the study of the variation of the coefficient of viscosity

The determination of the coefficient of viscosity of eruptive products gives useful elements to the knowledge of possible variations of composition and physical conditions of the magmas.     

动水压力对深水桥墩地震响应影响的研究综述

地震激励下处于深水中的桥墩和周围水体的相互作用将对桥梁结构的动力响应产生较大影响。首先对地震作用下水-桥墩的相互作用理论做了概括,给出了动水压力对桥墩的作用效应及各自的适用范围;对主要的三种考虑流固耦合效应的分析方法做了对比,探讨了地震作用下影响水-结构相互作用的主要因素,并对今后的研究提出了建议。     

Pictorial Series of the Manifestations of the Dynamics of the Earth

Studia Geophysica et Geodaetica -     

Evolution of the Source of the Active Region of the Sun

Geomagnetism and Aeronomy - The magnetic evolution of the active region of the Sun at the level of the photosphere has been studied. Magnetic synoptic maps of the 2007 Kitt Peak Observatory were...     

On the solution of the reverse problem of geodesics with the help of the chord

Резюме Дается вывод формул для вычислений длины хорды, длины и азимутов нормаляных сечений и длины геодезической линии эллипсоида. Применяются тригонометрические функции данных величин и постоянные принятого ргфгргнц-эллипсоида, что является целесообразным при использовании вычислителQjных машин, особенно автоматов. Рабочие формулы рекомендуются в форме (8–11).

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Dedicated to Professor František Fiala on His 85th Birthday

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Address: Veveři 95, Brno.     

Magnetic stratigraphy of the Ordovician in the lower reach of the Kotuy River: the age of the Bysy-Yuryakh stratum and the rate of geomagnetic reversals on the eve of the superchron

Until recently, the existing data prevented the geophysicists from accurately dating the Bysy-Yuryakh stratum, which outcrops in the middle reach of the Kotuy River, constraining the time of its formation to a wide interval from the end of the Late Cambrian to the beginning of the Silurian. The obtained paleomagnetic data unambiguously correlate the Bysy-Yuryakh stratum to the Nyaian regional stage and constrain its formation, at least a considerable part of it, by the Tremadocian. This result perfectly agrees with the data on the Bysy-Yuryakh conodonts studied in this work and yields a spectacular example of the successful application of paleomagnetic studies in solving important tasks of stratigraphy and, correspondingly, petroleum geology. Within the Bysy-Yuryakh stratum, we revealed a large normal-polarity interval corresponding to the long (>1 Ma) period when the geomagnetic reversals were absent. This result, in combination with the data for the Tremadocian and Middle–Upper Cambrian sequences of the other regions, indicates that (1) the rate of occurrence of the geomagnetic reversals on the eve of the Ordovician Moyero superchron of reversed polarity was at most one reversal per Ma; (2) the superchron does not switch on instantaneously but is preceded by a certain gradual change in the operation conditions of the dynamo mechanism which, inter alia, manifests itself by the reduction of the frequency of geomagnetic reversals with the approach of the superchron. This finding supports the views according to which a process preparing the establishment of the superchrons takes place at the core–mantle boundary.