新疆天山中部重力场时空变化特征研究

利用1987～2011年新疆地区的流动重力资料,对多期数据进行统一起算基准平差计算,绘制出新疆天山中部地区区域测段段差时序变化图、测线重力变化剖面图以及乌鲁木齐地区的重力场变化等值线图,并结合地震地质构造背景,分析新疆天山中部重力场变化特征.研究结果显示:独山子、宁家河测区重力变化较大,异常变化比较明显;乌鲁木齐地区相对稳定,空间分布比较集中,重力场正负变化区交替出现,重力场变化不大,能量正处于积累的过程.     

2016年射阳M_S 4.4地震前后重力场变化

利用江苏重力测网2014—2017年重力场观测资料,采用绝对重力控制与相对重力联测相结合的平差方法,获取2016年射阳M_S 4.4地震前后重力场变化图。根据射阳M_S 4.4地震前后射阳地区各测线重力段差变化特点,绘制重力场等值线并进行对比分析,结合相关机理,探讨重力场变化与该地震的内在联系。同震观测数据显示:射阳M_S 4.4地震发生在重力异常值高梯度带附近,发震时震中地区位于NS挤压正异常、EW张拉负异常状态,震后区域重力梯度变化量开始减小,是一种典型的重力异常调整现象。     

2016年射阳MS 4.4地震前后重力场变化

利用江苏重力测网2014-2017年重力场观测资料,采用绝对重力控制与相对重力联测相结合的平差方法,获取2016年射阳M_S 4.4地震前后重力场变化图。根据射阳M_S 4.4地震前后射阳地区各测线重力段差变化特点,绘制重力场等值线并进行对比分析,结合相关机理,探讨重力场变化与该地震的内在联系。同震观测数据显示：射阳M_S 4.4地震发生在重力异常值高梯度带附近,发震时震中地区位于NS挤压正异常、EW张拉负异常状态,震后区域重力梯度变化量开始减小,是一种典型的重力异常调整现象。     

北天山中段近期重力场变化特征研究

利用北天山中段最新的流动重力观测数据,通过整理计算平差,绘制该地区半年和一年尺度的重力场变化图像;选取横跨北天山中段乌鲁木齐、独山子两条测线,并分别绘制其重力剖面变化图;结合北天山中段地区动力构造环境,剖析该地区重力变化特征及其与地震孕育之间的关系。分析表明:北天山中段地区重力异常变化值不大,重力变化等值线图和剖面变化图均能较好地反映重力场随时空变化特征;北天山中段动态重力变化特征基本反映了该地区动力构造运动的外部环境;研究区域内的重力场空间格局分布特征较清晰,其重力变化具有明显的分区特征,山体和盆地之间的重力变化具有显著差异,山体与盆地边缘正负重力变化交替出现,且变化相对较平稳。     

河北唐山古冶5.1级地震前的重力变化

利用京津冀地区2018—2020年5月的流动重力观测资料,分析了2020年7月12日河北唐山古冶5.1级地震前不同时间尺度重力场变化.结果表明:0.5年尺度重力场变化图像较好地反映了此次地震"震前一年,重力场持续上升(正)变化→震前反向变化→在重力变化梯度带零等值线附近发震"的演化过程;震前0.5年和1年年尺度重力场均显示,地震发生在重力变化零等值线附近.     

关中地区重力场及其时空动态演化特征

系统分析了关中地区1992～2004年流动重力测量资料，研究了重力场的时空动态演化特征。10多年来的重力场动态变化图象表明：重力场变化与活动断裂构造密切相关，重力场有规律的变化与区域应力-应变场微动态活动有关。区域重力场总的趋势变化为：关中南部秦岭山区重力负值变化，测区中部渭河断陷盆地至韩城一带重力正值变化，测区北部铜川-黄龙一带的渭北黄土塬重力负值变化。西安城区重力变化主要是过量开采地下水、含水系统压密所致。     

彰武地震前后垂直形变场局部反向原因探索

以探索彰武地震前后垂直形变场局部反向原因为目的，利用动态秩亏平差方法处理辽宁地区水准、重力复测资料。依据重力场变化图按网格法计算重力场变化对垂直形变场的影响，绘制消除重力场变化影响的垂直形变场图。     

胶东测区重力场时空动态演化特征

系统分析了胶东测区1996—2009年期间流动重力测量资料,着重探讨了1996年以来相邻期的重力点值的空间变化规律,重力场有规律的变化表现为：胶东测区自观测以来有着活跃-平静-活跃-逐渐稳定的变化过程。另外,分析了胶东测区内断裂带附近的部分测点的点值和段差值变化特征,认为重力场变化与活动断裂构造密切相关,从而进一步加深了对胶东测区重力场时、空、强动态演化特征的初步认识,这为今后对山东地区重力场深入分析和研究打下了坚实的基础。     

四川地区流动重力资料的位场 分离与异常特征提取

用于监测四川地区重力场随时间变化的流动重力测网于2008年5月12日汶川M_S8.0地震后进行了全面改造, 形成了新的闭合环线并对整网点位每年实施2次重力观测工作. 该文以2010—2012年获取的5期流动重力资料为基础, 分别采用小波多尺度分解和三维视密度反演等位场分离方法, 对测区内重力场的动态变化进行多层次分解及异常特征提取, 以探求四川测区范围内重力异常动态变化特征以及地震前后不同深度范围内密度变化情况与重力场响应之间的关系. 结果表明, 对同一期资料进行小波分解得到不同阶次的细节图像, 揭示了不同深度处重力异常动态变化特征; 分解结果同时也表明了四川测区范围内重力场的变化形态与川内特有的断裂构造格架和深部结构环境及过渡带特征密切相关. 通过对不同时期的差分重力异常资料进行三维视密度反演对比研究发现, 在地震前后四川测区范围内由浅到深密度变化呈现出不同程度的差异, 震区附近出现较为明显的横向密度变化特征且浅层物质密度局部性的异常变化差异较为突出, 测区范围内中上地壳深度层密度反演切片显示出的趋势性差异基本上反映了地震前后测区内地下物质的动态变化趋势, 因此, 深刻认识不同深度范围内重力场的动态演化特征, 对研究壳内物质密度变化以及与地震的孕育和发展有关的深部介质环境具有积极的意义.      

华北中部重力场的动态变化及其强震危险含义

基于绝对和相对重力观测获得的区域重力场时、空动态变化,结合区域GPS测量资料与活动构造分析,本文研究了华北中部地区2009-2011年的重力场变化特征,讨论了该区域重力场动态变化的强震危险含义.结果主要表明:(1)华北中部的活动地块边界及部分重要活动断裂带两侧存在较大差异的重力场空间变化;其中,以山西断陷带北东段所在的晋冀蒙交界地区为中心,形成较大面积的重力负值变化区,且沿该区西北缘的NE向岱海-黄旗海断裂带以及东南缘的NNE向太行山山前断裂带附近分别形成重力变化的高梯度带,可能反映这些部位近年的构造或断裂活动显著.(2)不同时段的重力场差分动态演化图像可能反映了近年山西断陷带北东段(京西北盆-岭构造区)及其附近的重力场整体经历了"准均匀→非均匀→断陷带北段侧向显著变化→局部"硬化"的演化过程.(3)研究区重力场的时间累积变化图像可用"区域应力场增强→区域断裂与断块差异运动及变形增强→局部运动受阻"的过程进行解释.(4)研究区的一些重力异常部位存在中-长期强震危险背景.     

On the synchronism in the events within the core and on the surface of the earth: the changes in the organic world and in the polarity of the geomagnetic field in the phanerozoic

The data on geomagnetic reversals are compared with the changes in the organic world and with the lower-mantle plumes. The times of the formation of plumes and the times of their appearance on the Earth’s surface relate to the intervals characterized by the different frequencies of geomagnetic reversals, i.e., there is no interrelation between the formation of plumes and the frequency of the changes in the geomagnetic field polarity. At the same time, a certain synchronism is observed between the frequency of the geomagnetic reversals and the boundaries of the biostratigraphic ages, i.e., the changes in the organic world in the long-period range. A hypothesis is proposed, which explains the change in the sign of the geomagnetic field by the combined effect of the irregular rotation of the internal core relative to the mantle and the changes in the slope angle of the axis of the Earth’s rotation, which, in turn, results in synchronous events on the Earth’s surface: the rates of changes in the organic world.     

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.     

太平洋中部地磁台11年周期变化的研究

综合APIA、HONOLULU、PAMATAI 3个地磁台三分量的11年周期变化的形态后,可定性地提出该变化源于内场。如内源为核幔边界的电涡流,则其中心点应位于3台之间。     

On the use of the autocorrelation method for estimating the depth to the magnetic basement

The depth to the top of magnetic dykes can be estimated from total field aeromagnetic data using the relation between the depth to magnetic sources and the autocorrelation function of magnetic data. By using synthetic anomalies we show that in the ideal case, depth can be determined to an accuracy of 10% or better, when the anomaly sources are two-dimensional dykes. However, the estimated depths depend on the width of the dykes. The estimated depth is about 0.6 times the actual depth to the top of thin dykes, and around the true depth for thick dykes having width-to-depth ratio around 3. The depth is considerably overestimated for very thick dykes (e.g., contacts, which is a special case of the thick dyke). Thus, the autocorrelation method requires that the width-to-depth ratio of the dyke is estimated independently to correctly estimate the depths. Alternatively, it must be assumed that the width-to-depth ratio for the two-dimensional source body is between 1.5 and 4.     

固体潮的地震预测研究与地球动力学研究之分析比较

本文分析了现行固体潮地震研究中的历史影响,对比研究了固体潮地震预测研究和固体潮地球动力学研究二者在振动频率、振动源体积、传输距离与介质等方面的地球物理特点与本质区别,强调了固体潮地震预测研究中最根本的工作是建立地震预测的目标和基本概念.     

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     

Macrobenthic communities of the Pechora Sea: the past and the present on the threshhold of the prirazlomnoye oil-field exploitation

On data of bottom sampling, carried out by means of grab, trawl and underwater photography in August–September of 1993 in the area of the Pechora Sea, quantitative regularities of macrobenthos distribution are described for the ecological monitoring purposes. Maps of -biodiversity and biomass indices, bottom communities and trophic zones, singled out by dominant method, are presented. Assessment of structure changes of the investigated area bottom communities during the last 60–70 years is fulfilled. It is shown that the described communities on the whole are of natural undisturbed character and that the revealed changes are within the natural fluctuations in the abundance of benthic populations or may be interpreted in terms of methodical differences in the data analysis and generalization by different authors.     

On the maintenance of the axisymmetric part of the flow in the atmosphere

Summary The maintenance of the axisymmetric component of the flow in the atmosphere is investigated by means of a steady-state, quasi-geostrophic formulation of the meteorological equations. It is shown that the meridional variations in the time-averaged axisymmetric variables can be expressed as the sum of three contributions, one being due to the eddy heat transport, another to the eddy momentum transport, and a third to the convective-radiative equilibrium temperature which enters the problem through the specification of a Newtonian form of diabatic heating. The contributions by the large scale eddies are evaluated through the use of observed values for the eddy heat and momentum transports.The contributions from each of the three forcing mechanisms to the temperature and zonal wind fields are invstigated individually and found to be of about equal importance. The sum of the three contributions are also presented for the temperature, the zonal wind, the stream function associated with the mean meridional circulation and the corresponding vertical motion. Although the results fail to reproduce the main observed features of the lower stratosphere, they are found to be in good agreement with observations in the middle latitude troposphere. At any pressure level, for example, the computed mean zonal wind has a jet-like profile and the axis of the jet is found to slope to the south with height, as observed in the atmosphere.Based in part on a thesis submitted by the first author as partial fulfillment of the requirements for the Ph.D. degree at the University of Michigan. — Publication No. 194 from the Department of Meteorology and Oceanography, The University of Michigan.     

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。     

环太平洋俯冲带内双地震带及其成因机制研究进展

俯冲带作为地球最为庞大的循环系统的重要组成部分,已成为地球科学的研究热点之一.很多俯冲带,特别是环太平洋俯冲带内的中深源地震,在空间上呈明显的分层分布,并且各层地震具有不同的震源机制,即所谓的双地震带现象.本文简要介绍了环太平洋双地震带形态特征与震源机制的空间分布,并回顾了双地震带的几种成因模型.根据形态特征和震源机制的差异,中源深度的双地震带可以分为两类,其中,一类双地震带对应上、下二层分别为压缩和张性的地震分布;另一类双地震带的震源分布较浅,且其浅部地震以横向压缩为主.此外,日本本州东北俯冲带的地震分布可能是由三层地震带组成的,而且汤加、伊豆-小笠原地区还发现深源深度的双地震带.通过对双地震带的形态特征以及其热力学条件的研究,人们从抗弯作用、脱水脆化、相变断层等多方面,尝试建立解释双地震带成因的模型.目前,大多数研究利用数值计算结果,结合蛇纹石脱水脆化、相变断层模型,能够不同程度地分别解释中源和深源双地震带成因.不过,这些模型几乎相互独立,并不能同时解释中源和深源双地震带.有人试图尝试用统一模型解释中深源地震成因,例如,先前存在的断层模型,不过该模型还不很具有说服力.也可能是多种因素的联合作用,共同影响着俯冲板内的温度场、应力场分布.