中国地震震害特征及其意义

本文对1969年以前发生在中国境内的5级以上的地震震害进行了总结。提出了历史震害分布规律及震害出现次数与烈度曲线函数关系,给出震级与震害最大距离的关系公式。这些规律和公式,对震害预测和烈度小区划有一定参考价值。 我国有丰富的地震灾害记录,但至今还散落在各种地震文献之中,如果把这些资料进行整理,用之于生产建设,将有一定的实际意义。 据此目的,本文对公元前1177年至1969年间发生的地震进行了总结,并着重研究了震害情况     

2007年宁洱6.4级地震震害综述

给出了宁洱6.4级地震4个烈度区的分布情况,详细介绍了本次地震造成的各类建筑物震害、各烈度区的建筑结构特点和震害特征、生命线工程和水利设施的震害以及地表裂缝、滑坡和沙土液化及喷沙冒水等地震地质灾害,并对形成震害的原因进行了初步分析。     

天津市地震经济损失模型和生命损失模型的预测研究

文中主要探讨了由地震引起的天津市经济损失和生命损失的预测问题。首先阐述了天津市震害预测的 5个背景特点 :建筑物特点、地质条件特点、建筑场地划分特点、基本设防烈度特点以及地震烈度衰减关系特点 ,根据这 5个特点将天津市划分为含有 7种建筑结构形式的 4个区域的震害预测模式。在此基础上 ,分析了天津市地震经济损失模型和生命损失模型 ,考虑了时间因素 ,然后与1976年唐山大地震的实际震害结果进行了对比及修正 ,给出了天津市 4个区域的建筑物地震经济损失率模型、社会财富损失率模型和建筑物毁坏率模型 ,并给出了计算天津市建筑物地震经济损失、天津市国内生产总值GDP地震经济损失和天津市地震生命损失的表达式 ;最后 ,将天津市地区划分为2 85 8个震害评估单元 ,以近百年来在天津市区域内曾经发生的最大地震作为假想地震 ,预测分析了天津市建筑物地震经济损失分布和地震生命损失分布结果     

1989年大同—阳高地震的震害和灾害评估

叙述了大同—阳高地震的震害情况,讨论和分析了其特点和震害偏重的原因。介绍了地震后进行的震害指数调查和经济损失评估的工作情况,并结合震害指数的分布特点和震区的地震地质条件,分析了地震烈度的分布情况和特殊性,指出震害分布与发震构造有密切关系,认为把烈度和震害指数结合起来进行研究可更好地反映出这次震群活动的宏观特点。     

1999年11月29日岫岩—海城5.6级地震的烈度与震害

１９９９年１１月２９日在辽宁海城岫岩交界处发生了５．６级地震,这次地震造成的破坏、震中烈度达到了Ⅶ度,本文阐述了这次地震的宏观地震参数,烈度划分标度,烈度分布及震害特点等内容,与一般的５．５级左右地震相比,这次地震的特点是,震害偏重,震害分布不均匀,地震波的频谱效应从震害现象得到明显反映。     

2003年8月16日内蒙古MemSsub5.9地震震害分布特征及其成因分析

总结了根据应急科考震害调查资料确定的2003年8月16日内蒙古MS5.9地震的震害分布特征， 利用中国数字地震台网（CDSN）的长周期波形资料， 反演确定了该地震的地震矩张量解和震源机制解. 根据震源机制解、 余震分布和震害分布特征， 探讨了震害分布特点与震源机制的关系. 从全球强震记录、 历史地震资料和该地震的震害特点， 讨论了强地面运动的特点与震中区物理背景的关系. 调查表明， 此次地震的极震区呈东西走向， 与震源机制反演结果得到的断层走向一致. 极震区面积相对较大， 单层土木结构和砖木结构的房屋受损较严重， 可能与当地的震源物理环境有一定关系.      

广东省桥梁抽样调查与地震易损性评价

结合广东省水系分布抽样定位代表性大型、特大型桥梁位置,并在此基础上进行现场调研,着重了解这些大桥的基本属性和使用现状,同时借鉴四川汶川地震震害资料分析桥梁震害特点,进一步对所调查的桥梁做群体地震易损性分析,从而给出主要病害成因,提出完善桥梁设计理念和防震措施的一些意见。     

2008年瑞丽4.9级地震烈度及震害研究

给出瑞丽4.9级地震的烈度区的展布情况,详细介绍了烈度区内的建筑结构特点和震害特征,以及生命线工程和水利设施的震害,并对形成震害的原因进行了初步分析.     

鲁甸5.6级地震震害分析

通过对云南鲁甸5．6级地震中47个居民点的震害调查,给出了本次地震的等烈度分布图,分析了场地条件与震害的关系、各类房屋的震害特征、典型房屋震害累积效应以及生命线工程震害。结果表明：这次地震比2003年11月鲁甸5．1、5．0级两次地震破坏严重,形成了Ⅷ度破坏区及较大范围的Ⅶ度和Ⅵ度破坏区,盆地区的震害比基岩区的要重．其主要原因是：①盆地区广泛分布有软弱地层;②震区建筑结构简易,抗震能力极差;③三次地震震区基本重叠,震害累积效应表现突出。     

2018年9月8日云南墨江M5.9地震震害综述

2018年9月8日10时31分29秒,云南省墨江县(23.28°N,101.53°E)发生M5.9地震。根据现场调查情况,详细阐述地震灾区房屋建筑结构特点、房屋建筑及生命线工程震害特征,给出房屋建筑震害矩阵,对其震害成因进行分析,并与省内近年相似震级的地震震害进行对比分析,结果表明:本次地震波及范围广、总体震害轻、无人员死亡、地质灾害轻。     

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.     

On the gravimetric undulations of the geoid and the deflections of the vertical

Summary The author mentions the aims of the World-wide gravity project he established in the Ohio State University in Columbus, in 1950. He outlines the practical procedure of the gravimetric computations of the undulationsN and the vertical deflection components and and emphasizes that only by the global international cooperation and additional gravity observations at sea carried out during the last decade it has been possible to gather to Columbus the needed gravity material. Since there exist still large gravimetrically unsurveyed areas it is of vital significance to study what gravity anomalies are best to be used for these regions. The given figures concerning the accuracy of theN, and , estimated theoretically and obtained in practice, indicate that in the gravimetrically well surveyed parts of the world like in Europe and the United States we can get gravimetrically on basis of existing gravity material theN-values with accuracy of about 5–10 meters, and and with the accuracy of about 1. The geoid undulationsN are already computed in Columbus for more than 6000 points of the northern hemisphere. The sample maps show the interesting geoid of Europe and vicinity between the latitudes 60° and 30° and longitude 5° W and 30° E, drafted on basis of more than 1000N-values computed at the corners of 1°×1° squares. It is interesting to realize that the geoid undulations in all this area are positive, the extreme values being between 40 and 50 meters. The geophysical significance of the geoid maps of this kind is pointed out.     

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.     

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。     

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.     

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 variation in the geomagnetic dipole over the geological history of the Earth

The global database on the paleointensity, containing determinations of the virtual dipole moment (VDM) for a stable (normal) regime of the geomagnetic field in a time interval of up to 3.5 Ga, is supplemented by new VDM determinations and analyzed. The field generation process started no later than 3–3.5 Ga (earlier data are absent) at the stage of the Earth’s core formation. Since that time, the dipole value has differed from its present value by no more than an order of magnitude, and the deviations that have already been detected tend toward smaller values. The distribution of VDM values in the time interval 0–400 Ma is bimodal, which apparently reflects the presence of two different generation levels of the geomagnetic field distinguished by a relatively large value (close to the present field value) and a relatively small value (approximately half as large as the present value). The total duration of decreased VDM values appreciably exceeds that of increased VDM values (179.1 and 28.6 Myr, respectively). On the whole, data on the paleointensity do not contradict the hypothesis about the dipole nature of the field over the last 400 Myr; however, the number of determinations at high paleolatitudes is too small to draw decisive conclusions on the validity (or invalidity) of the dipole field approximation based solely on paleointensity data.     

Structure of the poleward wall of the trough and the inclination of the geomagnetic field above the EISCAT radar

A special high-resolution routine of the EISCAT radar has been used to investigate the structure and development of the poleward wall of a deep trough in electron density. The feature was tracked by the radar during a 7-hour period under very quiet geomagnetic conditions. The field-aligned nature of the structure enabled an estimate to be made of the inclination of the geomagnetic field above EISCAT that was in good agreement with the current model. Observations of narrow field-aligned enhancements in electron temperature demonstrated that the wall of this trough is a dynamic feature, reforming regularly as the electron density responds on a time scale of tens of minutes to energy input from soft-particle precipitation.