2012 年6 月30 日新疆新源-和静MS 6. 6地震序列震源机制解

利用CAP方法反演了2012年6月30日新源-和静Ms6.6地震序列震源机制解.反演得到Ms6.6地震节面Ⅰ的参数为:走向299°,倾角68°,滑动角164°;节面Ⅱ的参数为:走向35°,倾角75°,滑动角23°;P轴方位角166°,倾角5°,T轴方位角258°,倾角26°;矩震级Mw为6.3;矩心深度为21km.此次地震序列破裂优势方向为NWW,倾角以60°～90°为主,滑动角以±180°±30°为主;P轴方位的优势取向为近NS向,T轴优势取向为近EW向.初步分析表明,主震节面Ⅰ为发震断层,是走向为NWW、近乎直立的左旋走滑断层.此次6.6级地震震源断错性质和主压应力方向以及序列P轴优势方位与震源区周围构造应力场特征基本一致.     

2013年1月29日哈萨克斯坦MS6.1地震序列的震源机制解分析

北京时间2013年1月29日,哈萨克斯坦发生MS6.1地震,为了提高对地震震源机制解的认识,并进一步了解震源区的应力场特征,利用CAP方法反演了此次地震序列震源机制解.反演结果表明,MS6.1地震节面Ⅰ的参数：走向241°,倾角80°,滑动角7°;节面Ⅱ的参数：走向150°,倾角84°,滑动角170°;P轴方位为196°,倾角2°,T轴方位为105°,倾角12°;矩震级MW为6.1;矩心深度为13km;震源类型是左旋走滑型.此次地震序列破裂优势方向为NEE—SWW,倾角以30°～60°居多,滑动角以60°～120°、-60°～-120°居多;P轴方位的优势取向为近NE—SW向,接近水平的居优;T轴优势取向为近SEE—NWW向,接近垂直的居优;震源机制类型以倾向滑动型为主.反演结果与断层的分布、余震分布及哈萨克斯坦中天山（伊犁盆地西部）NEE—SWW向应力场有很好的一致性.     

2010年4月14日青海玉树Ms4.7、Ms7.1、Ms6.3地震震源机制解与发震构造研究

在整合CSN和青海、西藏、四川区域台网宽频带数字地震记录的基础上,采用“Cut and Paste”方法研究了2010年4月14日青海玉树地震序列中M4.7级前震、Ms7.1级主震、Ms6.3级强余震的震源机制解和可能的矩心深度,并结合震中附近活动断裂分布与地表破裂带调查资料讨论了发震构造.结果表明2010年4月14日青海玉树M7.1级主震的破裂面为走向129°,倾角84°,滑动角17°,矩心深度6 km左右,矩震级6.8级;Ms4.7级前震的破裂面为走向114°,倾角67°,滑动角-5°,矩心深度11 km左右,矩震级4.2级;Ms6.3级强余震的破裂面为走向123°、倾角89°、滑动角9°,矩心深度6 km左右,矩震级5.7级.本次地震序列的发震构造为甘孜-玉树-风火山断裂,地震破裂时以左旋走滑为主,地表破裂的总体走向与主震的破裂面走向基本一致,前震-主震-强余震的震源性质综合研究可推测发震构造在浅部的倾角陡立,到了深部有所变缓.     

2015年7月3日新疆皮山MS 6.5地震序列震源机制解及发震构造分析

2015年7月3日09时07分,在新疆皮山县发生M_(S)6.5地震,震源深度约10 km,主震后一段时间内陆续发生一系列大小不等的余震。使用新疆测震台网原始波形数据和中国地震台网编目数据库震相数据,采用CAP方法反演皮山M_(S)6.5地震及M_(S)3.5以上余震序列震源机制解,得到震源机制解参数,其中:节面Ⅰ走向为136°,倾角为34°,滑动角为94°;节面Ⅱ走向为311°,倾角为56°,滑动角为87°;最佳震源深度为21.3 km;矩震级为M_(W)6.3。据皮山地区地质构造和余震序列展布,基本确定节面Ⅰ为发震断层面;通过震源球判定本次地震的断层活动主要表现为逆冲型特征,破裂优势方向SE,倾角以20°—40°居多,滑动角以70°—120°居多。     

用CAP方法研究重庆荣昌2014年2月23日M_L3.8地震震源机制

利用CAP(cut-and-paste)法反演2014年2月23日重庆荣昌ML3.8地震震源机制,得到MW震级为3.04,节面Ⅰ走向46°、倾角44°、滑动角74°,节面Ⅱ走向247°、倾角48°、滑动角104°,P轴方位147.25°、仰角-2.09°,T轴方位46°、仰角-78.76°,表明该地震是带走滑分量的逆冲型地震。CAP测定的这次ML3.8地震的震源深度为3km,在油气的储层内,震源机制解中节面Ⅱ走向、倾角与震中附近的一条深度为1700m以下走向为SW230°倾向NW,倾角约45°的"腹底"逆断层基本一致。震中位于荣昌天然气田,附近有几口废水回注深井,曾发生大量的注水诱发地震。本次地震亦有可能是在区域主应力场的作用下,注水后岩石的孔隙压发生变化触发了盆地盖层内"腹底"断层活动的结果。     

2008年5月12日四川汶川8.0级地震与部分余震的震源机制解

采用区域和远台Pn或Pg初至波初动符号, 利用下半球等面积投影, 求解了2008年5月12日四川汶川8.0级地震和截止到2008年12月10日发生的部分4级以上余震的震源机制解。 汶川8.0级地震的震源机制为: 节面Ⅰ的走向为5°, 倾角为48°, 滑动角为39°; 节面Ⅱ的走向为247°, 倾角为62°, 滑动角为131°。 P轴方位角为309°, 仰角为8°, T轴方位角为208°, 仰角为54 °, B轴方位角为44°, 仰角为35°。 结合地质构造和余震空间分布, 可以确定节面Ⅱ为发震断层面。 根据震源机制解, 引发本次地震的断层活动主要表现为逆冲, 主破裂面为S67°W与该地震所在断层的走向基本一致(断裂总体走向N45°E)^[1]; 主压应力轴P轴为N51 °W, 主压应力轴P轴方位与该区域构造应力场方向基本一致。 根据余震震源机制解结果, 龙门山断裂带南段发生的余震与北段发生的余震的震源机制都具有优势分布, 且两者差异明显。 早期发生在南段的余震的破裂是以逆倾滑动为主, 兼有走向滑动; 而随着时间的推移, 余震向北段迁移, 在龙门山构造的北段地震震源的破裂方式以走向滑动为主, 兼有一定的逆倾滑动; 龙门构造带南段震源应力场受主震应力场的控制, 而龙门构造带北段震源应力场不仅受区域应力场的影响, 还受主震应力场的影响。     

永宁2次M_S4.5地震震源机制及深度

2010年6月22日和2012年11月20日在宁夏回族自治区银川市永宁县发生了2次M_s4.5地震,在银川市及周边地区引起了强烈震感。为了更好地认识这2次地震的发震构造,利用宁夏及邻近几个省份区域台网的近震波形资料,首先通过HyP2000绝对定位得到震中位置及余震震中分布;然后使用TDMT矩张量方法反演了震源机制解与震源深度。结果显示:2010年6月22日地震节面Ⅰ走向208°,倾角89°,滑动角-164°,节面Ⅱ走向117°,倾角74°,滑动角-2°;2012年11月20日地震节面Ⅰ走向284°,倾角79°,滑动角12°,节面Ⅱ走向192°,倾角78°,滑动角169°。综合Snoke法,得出这2次地震主控断层均为走向NNE、倾向NWW的右旋走滑断层;前者带有少量的拉张分量,后者带有少量逆冲分量,矩震级分别为M_w4.5和M_w4.3。根据HyP2000精定位、TDMT矩张量拟合误差和sPn深度震相等3种方法确定最佳震源深度分别为22km和8km,均属浅源地震。从定位震中和震源机制解来看,虽然2次地震震中仅差13km,但前者震源比后者深,分析其原因,可能为2012年11月20日地震由银川断裂的主断裂控制,而2010年6月22日地震由银川断裂的南支分断裂控制。     

2012年11月20日宁夏永宁MS4.6 地震震源机制解与发震构造

2012年11月20日在宁夏银川市永宁县与兴庆区交界处发生M_S4.6地震,为了更好地了解此次地震的发震构造,首先采用Hypo2000绝对定位方法得到该地震的震中位置及余震分布;然后采用CAP方法反演了此次地震的震源机制解和震源深度. 反演结果表明,永宁M_S4.6地震是一个带有少量逆冲分量的右旋走滑地震.该地震矩震级为M_W4.3,最佳双力偶解为:节面Ⅰ走向11°,倾角74°,滑动角171°;节面Ⅱ走向103°,倾角81°,滑动角16°.最佳震源深度为8km左右.从该地震震中和震源机制解以及震源深度剖面分布来看,这次地震很可能发生在银川隐伏主断层西侧的次级断层上.      

2019年6月17日四川长宁地震重定位及震源机制研究

采用双差重定位和W震相波形反演方法分析 “地震编目系统” 和中国地震台网中心提供的地震观测报告及区域地震波形数据,对2019年四川长宁地震序列进行了重定位,反演获取了M＞4.5地震的震源机制解。地震序列重定位结果显示,长宁地震序列沿NW优势方向呈条带状分布,集中分布于5—10 km深度范围,且发震断层面呈高倾角。震源机制反演结果表明,2019年6月17日四川长宁M_S6.0主震的两个可能发震断层面参数分别为:节面Ⅰ走向12°,倾角50°,滑动角139°;节面Ⅱ走向131°,倾角59°,滑动角48°,最优矩心深度为7.5 km,矩震级M_W5.74。此外几个M＞4.5余震的震源机制也基本与主震类似,均为以逆断为主外加少量走滑的地震破裂事件。综合分析长宁地震序列的重定位、震源机制反演结果以及震中和附近区域的地质构造背景信息推断,本次长宁主震的发震破裂面呈NW?SE走向,发震断层为长宁—双河背斜东北翼发育的逆冲断层。      

用CAP方法研究安庆4.8级地震震源机制

利用CAP方法反演了2011年1月19日安庆Ms4.8地震震源机制解.反演得到震级Mw =4.1,节面I走向角16°、倾角74°、滑移角120°;节面Ⅱ走向131°,倾角33°,滑移角30°;震源深度为3km.两个节面的走向与震中附近的宿松-枞阳断裂的走向相差较大,加之前人的地质考察结果显示,该断裂晚第四纪以来地震活动性较弱,故认为宿松-枞阳断裂是安庆Ms 4.8地震发震构造的可能性较小,本次地震很可能是北北东向的隐伏断层活动的结果.     

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.     

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...     

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.     

Influence of the topography of the surface of the Earth on vertical sounding of the temperature profile

Atmospheric temperature and humidity fields as well as information on other meteorological parameters are nowadays retrieved from radiance measurements recorded by operational meteorological satellites. Up to now, the inversion procedures used only take into account crude information on the topography of the Earth’s surface. However, the applied radiative transfer codes have to consider the Earth’s surface as the lower boundary of the atmospheric model and, therefore, need a more precise mean elevation and a classification of the roughness of the Earth’s surface. The influence of the topography of the Earth surface on retrieved temperature profiles is studied by using a physico-statistical inversion method. An objective analysis is made of the more precise mean elevation and derivation of roughness parameters using a new high-resolution digital elevation model (DEM) with a resolution of 500 m×500 m. By means of a geomorphological process and a newly developed topography rejection test, areas with a high surface roughness are localized and singled out. The influence of topography on the retrieved temperature profiles is illustrated by case studies. Changes are found predominantly in areas with a high variation of topography. Using the new high-resolution DEM and the topography rejection test, the geographical position of the calculated temperature profiles tends to be shifted towards areas with a small vertical variation of topography. The mean elevation determined by the new elevation model better characterizes the area observed. Hence, the temperature profiles can be calculated down to lower atmospheric levels. Furthermore, a guess profile better describing the atmospheric situation is selected by the more precise elevation. In addition, the temperature profiles obtained near the coast are improved considerably by the more precise determination of the surface property ‘sea’ and ‘land,’ respectively. Integration of an independent physical information such as topography leads, on average, to a slight improvement of the results of the physico-statistical inversion procedure. In some cases, however, significant improvements have been achieved regarding the desired accuracy of temperature profiles of the order of 1 K. In future, the spatial resolution of new high-resolution sounding instrumentation on the next generation of operational meteorological satellites will be increased. To exploit the resolving power of this new instrumentation, the different variation of the topography of the Earth surface, especially in regions with a high variation of topography, can be taken into account more precisely by using a high-resolution DEM.     

The effect of the pollution of the ground layer of the atmosphere on the albedo

Summary A simple model is proposed suitable for studying the effect of the ground layer of the atmosphere, polluted by aerosol, on the albedo. This model is founded on solving the equation of transfer of radiative energy. The numerical results are discussed, particular attention being paid to the analysis of errors due to neglecting the multiple reflection of solar radiation on the aerosol particles. A method which would also include the multiple reflection is proposed, and the conditions under which the presence of the aerosol is responsible for an increase or decrease of the solar radiation balance on the Earth's surface, are analysed.     

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.     

Evolutionary Changes in the Configuration of the Magnetic Field of the Solar Corona in the Epoch of the Minimum

Geomagnetism and Aeronomy - The evolution of the magnetic configuration in the solar corona is studied. The curvature of the K-corona helmets obtained from an analytical approximation of the...