Crustal Movement in the Northern Part of North China Associated with Zhangbei Earthquake     

Yang Guohu  Wang Min  Han Yueping 《中国地震研究》2002,16(1):81-89

Crustal Deformation Monitoring Center, China Seismological Bureau, Tianjin 300180, China Crustal deformation in the northern part of North China associated with Zhangbei earthquake is analyzed using GPS data collected during 1992, 1996 and 1999, precise re-leveling data collected during 1992, 1998 and 2000, and INSAR result (September 22, 1997～May 6, 1998). The results indicate: ① The vertical deformation is not remarkable since 1992. The vertical crustal deformation in the central and northern part of North China in recent 10 years is of inheritance. The scope of the significant deformation is 15km×15km with a magnitude of 250mm when the event occurred. ② The horizontal deformation is not remarkable in any unit of North China. ③ Before and after the event (1992～1996 and 1996～1999), there is kinematic change of horizontal motion between different units. The activity mode along Yinshan tectonic zone changed from relative static state to left-lateral strike slip; The dominant extensional movement along Shanxi rift zone changed to right-lateral strike slip; Yanshan tectonic zone changed from left-lateral strike-slip with extension to left-lateral strike slip; Yanshan-Hebei transitional zone formed before the event disappeared after the event. ④ The scale of the deformation is closely related to the physical property of media and geological structure environment. Further analysis indicates that ① Zhangbei earthquake does not mean that the earthquake activity begins to be strengthened in North China; ② The crustal movement is normal at present; ③ Next stronger earthquake in North China might be located in Yanshan tectonic zone, especially at its both ends, and Shanxi tectonic zone.  相似文献   

震源物理:进展和趋势     

牛志仁 《地球物理学进展》1992,(3)

本文根据第二十届IUGG大会交流的情况和提供的材料,结合作者以往的文献积累,评述了近四年震源物理的主要进展和趋势.主要内容分为地震动力学破裂复杂性的研究,摩擦本构行为和失稳机制的研究,线弹性断裂力学的应用,分形和混沌等四个方面.  相似文献   

Trends in Cretaceous and Tertiary geomagnetic reversals     

R.A. Reyment 《Cretaceous Research》1980,1(1):27-48

The statistical theory of modulated renewal processes is used to analyze the polarity reversal scales of Larson & Hilde (1975) and LaBreque, Kent & Cande (1977). The results suggest that the trending effect in these data may be modelled by a rate parameter with an exponential quadratic trend. Short times in one polarity state tend to be followed by short times in the other state. The graphical analysis points to the possibility of an undulating pattern in reversal rates. The empirical distributions of the normal and reversed polarities show slight differences in comparison with each other in most of the statistical tests, but a moving-window analysis indicates possible serial effects for the normal times. As a rough approximation, a statistical two-state model for reversals might be realistic, for example, an alternating renewal process under relaxed assumptions. There has been a gradual stepping-up of the minimum reversal rate from the Oligocene to the present, but little change in the observed range of the reversal rates. With the long quiet (Mercanton) interval removed from the data, the average time spent in the reversed polarity state is slightly greater than for the normal state. A change in statistical properties for the entire set of data considered as a single sample occurs around the Eocene-Oligocene transition (Middle Eocene on earlier time scales). The analyses of the statistical second-order properties of the entire sequence of 271 observations, and the subsets of normal and reversed between-times, reject a renewal hypothesis if theoretical statistical considerations are strictly applied to the results (although this hypothesis is not rejected for the Oligocene to Recent observations); this result is at variance with some geophysical models. A short appendix on the theory of point processes is provided to aid the general reader in following the arguments used in this paper.  相似文献   

黄河径流量的历史演变规律及成因   总被引：31，自引：0，他引：31       下载免费PDF全文

马柱国 《地球物理学报》2005,48(6):1270-1275

基于黄河上、中和下游的径流及气候资料，对径流的年代际变化规律及与气候变化的关系进行了分析.结果表明：黄河流域的径流均存在显著的年代际变化趋势，径流的显著特征是从20世纪80年代开始的减少趋势，但并未达到历史的最低，径流减少的趋势在下游比上游更显著，而这种变化趋势与流域的气候变化趋势基本一致，说明在年代际尺度上，径流的变化主要受气候的控制；在不同季节，这种关系有明显差异，如在冬季两者的变化趋势有较大差异.分析还发现，近年来流域地表的干化是流域径流减少的原因，气温的升高更加剧了流域地表干化.  相似文献   

河南省夏玉米产量预报方法   总被引：4，自引：0，他引：4  

杨海鹰付祥建  马振生白凌霞 《河南气象》2005,(2):25-26

利用河南省农业气象产量预报业务系(WAPFOS)，分析了夏玉米产量与光照、降水、气温等影响因子的关系，结果表明，旬降水量、旬日照时数和旬平均气温与夏玉米产量关系密切，是直接影响产量的重要因素。在此基础上，建立了预报模型。  相似文献   

The Application of Wavelet Transform in Analysis of Digital Precursory Observational Data     

Song Zhiping 《中国地震研究》2004,18(3):225-233

Digital data of precursors is noted for its high accuracy. Therefore, it is important to extract the high frequency information from the low ones in the digital data of precursors and todiscriminate between the trend anomalies and the short-term anomalies. This paper presents a method to separate the high frequency information from the low ones by using the wavelet transform to analyze the digital data of precursors, and illustrates with examples the train of thoughts of discriminating the short-term anomalies from trend anomalies by using the wavelet transform, thus provide a new effective approach for extracting the short-term and trend anomalies from the digital data of precursors.  相似文献   

中强以上地震发生后半年内地震趋势的模糊聚类分析     

曾健  韩渭宾  王虹  席敦礼 《内陆地震》1995,9(1):62-69

利用１次中强以上地震（Ｍ０≥４．７）发生后前６天地震序列的资料，对未来半年内是否可能发生相当（Ｍ＝Ｍ０±０．３）或更大的地震进行模糊聚类分析．根据３６个初选问题的Ｗａｌｌｅｎ评分，精选出１３项能突出表现地震序列的特征参数作为指标．应用模糊聚类的ＦＣＭ算法对地震序列进行分类，Ⅰ类为Ｍ０级中强震后６个月内还有震级为Ｍ≥Ｍ０－０．３级的地震发生；Ⅱ类为Ｍ０级中强震后６个月内无相当或更大的地震。以中国大陆地区１９６６年以来的４８次Ｍ０≥４．７级中强震序列资料建立震后判别模型，然后对近期发生的８次强震序列进行了外推检验。  相似文献   

古地理过程研究的方法与实例—以洛川黄土剖面为例   总被引：3，自引：0，他引：3  

程伟民  肖宁川 《地理学报》1993,48(2):131-142

本文选取陕西省洛川县黑木沟黄土剖面中CaCO_3含量、粉粘比(kd值)、FeO/Fe_2O_3以及SiO_2/Al_2O_3等指标,运用相关分析、聚类分析、投影变换等数学方法,研究这一地区中、晚更新世古地理演变过程。结果表明,洛川地区在中、晚更新世经历了5种类型的自然环境和9次地理旋迴,地理旋迴的周期和变化幅度不断增大,自然环境朝干冷方向演变。  相似文献   

Comparison of forecasting performance of nonlinear models of hydrological time series   总被引：1，自引：0，他引：1  

Jozef Komorník  Radko Mesiar  Danuša Szökeová 《Physics and Chemistry of the Earth》2006,31(18):1127-1145

Mean monthly flows of the Tatry alpine mountain region in Slovakia are predominantly fed by snowmelt in the spring and convective precipitation in the summer. Therefore their regime properties exhibit clear seasonal patterns. Positive deviations from these trends have substantially different features than the negative ones. This provides intuitive justification for the application of nonlinear two-regime models for modelling and forecasting of these time series. Nonlinear time series structures often have lead to good fitting performances, however these do not guarantee an equally good forecasting performance. In this paper therefore the forecasting performance of several nonlinear time series models is compared with respect to their capabilities of forecasting monthly and seasonal flows in the Tatry region. A new type of regime-switching models is also proposed and tested. The best predictive performance was achieved for a new model subclass involving aggregation operators.  相似文献   

江苏省雨日及降水量的气候变化研究   总被引：3，自引：1，他引：3       下载免费PDF全文

王颖  封国林  施能  甄淑红 《气象科学》2007,27(3):287-293

利用江苏省1960—2000年13个测站逐日降水资料,分析了41 a来江苏省年、季、月雨日的时空特征和雨日的气候变化。结果表明,江苏省的年雨日已经明显减少,平均每10 a雨日减少10.4 d。各季的雨日都呈负趋势,平均每10 a季雨日减少2.6 d。而秋季雨日减少最明显也最多。雨日长期趋势变化有明显的空间变化。江苏省的年雨日东部比西部减少的多,东部雨日每10 a减少14.6 d。月雨日也呈减少趋势,尤以4月、9月明显。雨日的长期趋势变化与降水量的长期趋势变化并不完全一致,这种不一致表现在长期趋势变化的强度上、范围上。总的来说,雨日的负趋势变化要强于降水量,负趋势的范围也要比降水量来得广一些。  相似文献