跨断层形变测量异常特征分析

在统计近40年我国强震前跨断层形变异常的基础上, 对异常持续时间、 异常空间分布、 异常幅度特征及它们之间的关系进行了分析, 讨论了跨断层形变观测异常特征和监测不同震级地震跨断层场地的最大间距及观测周期。 结果表明: 异常主要以中短期和中期异常为主, 尤其在震前1年内异常最多; 异常持续时间与震级呈正比例的关系; 异常在空间分布上有随震级增大而扩大的现象; 异常幅度有随异常持续时间增大而增大的趋势; 震中距在160~350 km范围内异常幅度较大; 异常形态主要分为趋势型和突变型两种。 监测不同震级的地震跨断层形变场地间距可以不同, 监测7级地震形变场地间距应小于450 km; 6级应小于300 km; 5级应小于200 km; 4级应小于100 km。 跨断层形变观测周期应不大于3个月。     

青藏高原北部地区地震窗口特征及其预报意义

利用青藏高原北部地区弱震活动资料筛选出3个具有中短期预报效能的地震窗口,分析了Ms≥5．0地震前各个窗口的异常特征,提取出半定量的中短期预报指标．即：在中强地震前80％的异常出现在地震前1～6个月,以中心异常出现时间向后推1～6个月作为预测的发震时间;异常幅度与未来震级之间没有明显的对应关系．对于7级以上大地震,古浪窗的显异常主要对应边界水平剪切走滑活动断裂上发生的地震;舟曲窗和乌海窗的显异常主要对应活动块体内部挤压逆冲断裂上发生的地震．而5～6级的中等地震没有明显的对应规律．     

张渤带形变预测指标分析

根据张渤带震例研究成果, 系统清理1966年以来张渤带5级以上地震前形变异常变化的各项特征, 初步归纳出张渤带的形变预测指标。 主要指标为: 张渤带5.6~6.2级地震异常相对集中, 异常主要集中在110~270 km范围; 潮汐类、 突变类异常数量相对较少; 破年变类异常较多, 异常主要对应4.5~5级和6~6.5级地震, 异常对应范围主要为100~300 km; 趋势转折类异常主要对应5.5~6.5级地震, 且异常时间在4.5~6.5级范围内有随震级增大而增加的趋势。     

清水李沟井与礼县石桥井流量异常变化与地震的关系

分析了清水李沟井与礼县石桥井汉量变化与邻近地区发生的中强地震的对应关系。发现在邻近地区发生的部分中强地震前半年左右2口井的流量开始出现上升或波动现象，异常变化的幅度最大可达3．75mL/s，对震级较小，而且距离较远的地震无明显的异常反映。2口井流量异常对5级地震的映震范围为250km，6级地震为350km，7级地震为500km。     

清水李沟井与礼县石桥井流量异常变化与地震的关系

分析了清水李沟井与礼县石桥井流量变化与邻近地区发生的中强地震的对应关系.发现在邻近地区发生的部分中强地震前半年左右2口井的流量开始出现上升或波动现象,异常变化的幅度最大可达3.75mL/s,对震级较小,而且距离较远的地震无明显的异常反映.2口井流量异常对5级地震的映震范围为250km,6级地震为350km,7级地震为500km.     

2022年1月8日青海门源6.9级地震前临震微波动现象初步研究

利用国家测震台网观测资料,对2022年1月8日青海门源6.9级地震震中距200km以内的19个台站自2021年记录到的临震微波动事件进行分析,发现震中距103km的祁连台在震前3个月存在显著异常,临震微波动事件的活动度(N值)高达20;震中距158km的拉脊山台同样出现活动度高值异常,达到异常指标;震中124km的湟源台长期处于异常状态,但在震前3～4个月表现为明显高于背景值的高值异常。其他台站虽然未达到异常指标,但震前3个多月活跃天数显著增加。异常显著的台站与震中位置呈线性分布,震中NW—SE方向的台站记录的事件更显著;本次地震前的微波动现象与2021年玛多7.4级地震前的微波动现象存在共同特征,可能与两次地震相似的震源机制解有关。     

福建省内陆4.5级以上地震前的时空异常特征

分析讨论了福建省内陆龙岩-永安交界区1992年以来发生的3次4．5级以上地震前BP、C、D、乱和YH共5个地震活动性参数的时空扫描图像,发现这5个地震活动性参数的时空扫描图像在地震前确有异常存在。在同一地震前,5个地震活动性参数空间扫描图像的异常起始时间具有较好的同步性;异常出现后,主震最快在1年3个月发生,最迟在2年3个月发生;未来主震都发生在异常达最大面积时的区域内;未来主震震级与异常持续时间和异常最大面积存在一定的正相关关系。     

腾冲地区潜热通量与周围地区地震活动的相关性

以2000年以来6.4级以上地震为例,研究了腾冲地区潜热通量（SLHF）在这些震例发生前后的变化特征。结果表明：腾冲地区的SLHF动态,不但在其附近发生强地震前常出现异常,而且对周边较远的强地震前也会发生异常反应;异常出现时间大都在震前1个半月以内,汶川地震前异常出现较早,发生在震前2个月之前,这可能与汶川地震震级高影响范围大有关;异常幅值与震级有关,震级越大,异常表现越强。 比如芦山7.0级地震、缅甸7.0级地震和汶川M_S 8.0地震前,腾冲地区SLHF异常幅度很大,远远超过最大参考值,而姚安6.5级地震和宁洱6.4级地震前异常幅度就相对小一些。腾冲地区SLHF异常与周围强地震的发生有较好的相关性,一方面与腾冲地区的活动断裂发育、现今构造变形强烈有关,另一方面可能是由于腾冲地区火山活动强烈,温泉广泛发育,水热交换迅速,对周边构造活动感应灵敏所致。     

木里地区地震震源参数特征研究

选取了2011年9月至2016年9月地震数据及资料,研究了水库水位与地震时空活动特征,计算了168次ML3.0级以上地震的震源参数.结果显示:区域视应力值随震级的增大而增大,反映了不同震级地震在应力水平积累等方面的差异;视应力有随地震矩增大而增大的趋势,意味着人类活动可能为该区域地震活动的主要因素;拐角频率与震级的关系可分为两段来看,当震级范围为ML3.0～3.5时,拐角频率随震级增大而降低的现象并不明显,当震级范围为ML3.5～4.4时,拐角频率随震级增大而降低,表明震级越大,库区破裂尺度在增大,反应了区域应力积累,应力水平有所增强;视应力时空分布特征显示,视应力随时间变化与频次存在着一定的相关性,且整体视应力水平逐渐增高,且最大地震发生在大坝附近,这些现象都可能为水库蓄水导致区域构造环境发生变化而造成.     

乌鲁木齐红山台地倾斜固体潮调和分析初探

采用Venedikov调和分析方法定量分析了乌鲁木齐红山台SQ-70倾斜仪固体潮M2波潮汐因子的震兆异常特征,发现红山台固体潮潮汐因子与周围100km范围内的4级以上地震以及250km范围内的5级以上地震对应较好,具有较高的预报效能。     

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。     

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.     

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.     

Pictorial Series of the Manifestations of the Dynamics of the Earth

Studia Geophysica et Geodaetica -     

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。     

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...     

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.     

On the determination of the non-linearity of the gravimeter scale

Summary The results of two different methods of the determination of the non-linearity of the gravimeter scale are compared; the economy is discussed as well.