通过子波变换分析宫崎大震前后鹿屋台地磁垂直分量的变化

1996年10月19日日本九州宫崎发生71级地震,震中离鹿屋地磁台约90km。作者将子波变换后的鹿屋与武汉(或成都)台的Z时均值资料进行比较,发现临震前后的“日变幅差”有异常存在。     

磁暴特性统计分析

本文使用柿岗(1924—1981年)女满别和鹿屋(1958—1981年)的磁暴资料,对磁暴的各种特性,进行了统计分析。为进一步验证这些结果,又用IAGA1968—1981年的SSC资料进行了对比分析,其主要研究成果如下: 1)柿岗SSC的发生频次的日变化,早晨5—7点最小,9点开始急剧增加,并且在白天18点以前多,夜间至清晨少。与IAGA资料中同期的日变化相比,两者的变化基本相似。 2)柿岗SC的幅度△H(nT)的日变化,夜间大,上午8—10点最小。而且在女满别最大的幅度比柿岗和鹿屋的都大,最小的幅度比柿岗和鹿屋的又都小。也就是说,越往北,日变化小,幅度越大。因此,可看作是由在高纬度地区的两个急始涡旋电流带来的影响。     

日本鹿屋台地磁转换函数的变化

1996年10月19日本九州宫崎发生7．1级大地震，震中离鹿屋地磁台约90km。分析了鹿屋台1989～2001年分钟值资料。周期等于60min和41min的地磁转换函数Au在1993年至1998年初呈现下降趋势。年变率达0．01α^-1。此变化有可能与宫崎地震相关。另外，从震前数年Parkinson矢量转向特征推测，震源区的电导率似乎是变小的。     

日本鹿屋台地磁静日变化中可能存在的震磁效应

１９９６年１０月１９日日本九州宫崎（Ｍｉｙａｚａｋｉ）发生７．１级地城,城中距鹿层地磁台约９０ｋｍ。利用Ｓｑ单台Ｚ／Ｈ法分析了１９８１～１９９８年鹿屋台与佘山台的资料,再研究两台视深比随时间的变化,结果表明,地震前一年多时间内视深化出现较大的负异常,同期的佘山与武汉台的视深比曲线未出现类似的异现象。因此,上述异常可能与宫崎地震有关。     

磁暴与太阳黑子的相关性

磁暴是太阳活动与地磁场相互作用所引起的一种复杂的地球物理效应。它们之间的活动相关性已得到了一些定性的了解。例如,据统计分析1937—1959年的580个太阳大耀斑表明,有50％的大耀斑可以引起磁暴。以及太阳黑子数与地磁活动程度(u)之间的11年周期变化等。为了解磁暴与太阳黑子的关系,本文利用太阳黑子相对数与日本柿岗地磁台1948—1978年间(其中所缺的1959—1962年的资料利用鹿屋台资料)每年出现的磁暴数,并     

《华南地震》2003年第23卷总目次

第　 1　期中小地震的流磁异常信息刘义高 ,方　谦 ,郎效龄 ,汪继林 (1)………………………………………………日本鹿屋台地磁转换函数的变化陈伯舫 (8)………………………………………………………………………上海及邻区的地壳形变速率与地震活动宋先月 ,宋治平 ,张　肃 ,汪育新 ,倪友忠 (13)…………………南海东北部滨海断裂的研究现状与展望赵明辉 ,丘学林 ,夏戡原 ,叶春明 (2 0 )……………………………水库诱发地震研究的历史、现状与发展趋势易立新 ,车用太 ,王广才 (2 8)…………………………………磁暴二倍法预报大震的物理机制讨…     

包头—乌拉特前旗震群序列及区域小震活动、局部应力场特征

1982年12月8日至1983年3月8日,在内蒙古包头至乌拉特前旗之间一度出现了频度、强度均较高的震群活动,分别在12月8日、2月9日、2月12日发生了Ms=4.6、4.2、4.4级三次中等地震,引起人们极大的关注。在此之前,1982年1月至11月,阴山地震带出现了自唐山大震后未曾有过的长达11个月的平静。12月8日4.6级地震突然发生后,紧接着,12月10日北京马道峪发生4.5级地震,12月24日丰镇发生4.2级地震,1983年1月17日磴口发生5.2级地震,2月9日、2月12日又在上述地区     

印度洋"12·26"百日祭--地震与海啸科普工作札记

从2004年12月26日,到2005年4月4日,计人首尾两天,整整百日。次日,4月5日又是清明。东方人很在意对亡的祭祀,很在意百日祭奠,尤其是恰恰赶在清明时节,愿以此百日祭奠寄托生对亡的无尽哀思,也以此作为我们生对改善自身生存环境的一种警醒。     

一九七六年中国六级以上地震目录

时 间;‘。-地 点-回级(MS)2月23日 台湾省玉里6.33月20日 台湾省莲花东南6. 04丹;田。、、。内蒙古和柞貉尔-巳T—-。5月29 Wr 云南省龙陵-7·5 29日——7.eru 31日”6.56月 1日”6.二 9日”6.17月4日”,-6.0 21日”6.6 28日 河北省唐山。丰南7.8 28日”7.18月16日 四川省松潘7.2 22日”6.7 23日”7.39月23日 宁夏吉兰泰 6.311月7日 云南省宁菠、盐源6.9. 15日 河北唐山、丰南6.912月12日 北纬30.3度东经137.5度6.1 13日 云南省宁菠6.吕一九七六年中国六级以上地震目录~~…     

昔阳4.9级地震前地声异常简析

一、事件 1982年11月12日凌晨,山西省昔阳县发生4.9级地震,附近各县均有较强感觉。当地群众震前普遍听到了地声,是我区近年来发生的一次较大地震。 介休地声观测站地处构造带交汇部位,在昔阳南西175公里处。安装在315米地声观测井底部的水听器,震前记到了较强的长期连续地声,出现的时间是,10月29日、30日,11月2日、3日、4日,11日平静,12日发生地震,同时纪录到地震波(见图)。     

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.