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On October 27, 2001, a large earthquake with Ms6.0, named the Yongsheng earthquake, occurred along the Jinshajiang segment of Chenghai fault in Yongsheng County, Yuunan Province. It is the largest event to occur along the Chenghai fault in the last 200 years. The seismo-geological survey shows that the seismogenic fault, which is the Jinshajiang segment of Chenghal fault, takes left-lateral strike-slip as its dominant movement pattern. According to differences in vertical motion, motion time, landforms and scales, the Chenhai fault can be divided into eight segments. The Jinshajiang segment has a vertical dislocation rate of 0.4mm/a, far lower than the mean rate of the Chenghai fault, about 2.0 mm/a. It‘ s deduced that the two sides of Jinshajiang segment “stuck“ tightly and hindered the strike-slip of the Chenghai fault. The strong earthquake distribution before this event shows that the Jinshajiang segment was in the seismic gap. The Chenghai fault, as a boundary of tectonic sub-blocks, makes the Northwest Yunnan block and the Middle Yunnan block move clockwise, and their margins move oppositely along the Chenghai fault. In the motion process of the Chenghai fault, structural hindrance and the seismic gap of strong earthquakes are propitious to the concentration and accumulation of structure stress. As a result, the Yongsheng Ms6.0 earthquake occurred. The Sujiazhuang-Shangangfu segment is similar to the Jinshajiang segment with a low vertical motion rate of 0.3 mm/a and in the seismic gap. So it‘s postulated that the segment may become a new structure hindrance, and the Yongsheng Ms6.0 earthquake may trigger the occurrence of future large earthquakes along this segment. 相似文献
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Wan Yongge 《中国地震研究》2007,21(1):33-42
The influences upon aftershocks of Coulomb failure stress change (CFSC) generated by the main-shock of the October 8, 2005, Pakistan earthquake are calculated and analyzed. The following factors are included in the calculation: (1) the difference between the pore fluid pressure and the medium elastic constant in the fault plane area and those of its surrounding medium; (2) the tectonic stress direction of the seismic source area; (3) the aftershock failure mechanism of aftershocks is calculated by stacking the tectonic stress with the stress change generated by the main-shock. Our study, which includes many factors, fits fairly well with the aftershock distribution. It indicates that most of the aftershocks were triggered by the Pakistan main-shock that occurred on October 8, 2005. 相似文献
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Ma Hongsheng 《中国地震研究》2006,20(3):232-243
INTRODUCTIONThe active blocks refer tothe geologic units that formedinlate Cenozoic (100 ~120 ka BP) andhave been highly active as fault zones since late Quaternary with relatively uniform motion styles(Zhang Guomin,et al .,2000 ;Zhang Peizhen,et al .,2003) .The active blocks are relativelyintactand have uniformmotion modalities ,their boundary zones (also called the active boundaries) are thelocalized or centralized zones of interactions and differential movement among the active block… 相似文献
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Yin Gongming Xu Xiwei Sun Yingjie Chen Jie and Liu AiguoInstitute of Geology SSB Beijing China 《中国地震研究》1997,(4)
The northern Liulengshan piedmont fault is located along the southern margin of the Yangyuan basin and represents a dip-slip normal fault,generally NEE-trending and NNW-dipping.Landforms offset by the fault are fairly developed and well preserved in the Dushanpu area of Yangyuan County,Hebei Province.Two trenches were excavated in front of a scarp of the northern Liulengshan piedmont fault at Dushanpu and two paleoseismic events were revealed in the trenches,from which several samples were collected for dating.The samples were dated using the IRSL dating technique.The preliminary result shows the possible ages of the two paleoseismic events. 相似文献
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The results of a spherical harmonic analysis and a sector spherical harmonic analysis of the solar magnetic field on the photosphere, source surface, and in the Earth’s orbit on July 10–20, 2004, were compared. It was found that the field values according to a sector harmonic analysis are an order of magnitude as large as the same values according to a spherical harmonic analysis and differ in the configuration. A twocomponent magnetic field structure was revealed: short-range sources are better described by a sector spherical harmonic analysis; long-range sources are better described by a spherical harmonic analysis. This is caused by the different depths of the occurrence of sources below the photosphere. 相似文献
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Abstract An investigation is made of the evolution of small-scale, axisymmetric vortices in a stratified fluid with spatially variable Coriolis parameter. The criteria for smadness are a horizontal scale less than or equal to the first internal radius of deformation and a vertical scale less than or equal to that of the ambient stratification. These circumstances match those of Sub-mesoscale, Coherent Vortices frequently observed in the oceans. The dynamical model is the balance equations, which include various effects of finite Rossby number. The principal topics are the regime of nearly uniform propagation, the development of an equilibrium ratio of vertical and horizontal scales (i.e., Burger number selection), and the occurrence of various types of instability for vortices with extremes in amplitude or shape. 相似文献
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Yasuo Miyabuchi Shin-ichiro Ikebe Kazunori Watanabe 《Journal of Volcanology and Geothermal Research》2008
The active crater of Nakadake at Aso Volcano, southwestern Japan, has been occupied by a lake during its dormant periods. Multiple ash emissions were observed from the crater lake between July 2003 and August 2005. The largest events occurred on 10 July 2003 and 14 January 2004. On 10 July 2003, ash (41 tons) was dispersed throughout an area extending 14 km east-northeast of the vent, and on 14 January 2004 ash (32 tons) extended 8 km to the east-southeast. Thereafter, small ash emissions were frequent at the crater lake, in which the water level fell considerably from April to August 2005. During this period major ash emitting events, producing mostly white aggregated ash, occurred on June 10–12, June 21 (4.2 tons) and July 25 (1.2 tons). Ash emissions at the Nakadake crater in 2003–2005 were classified into three types: gentle release of white aggregated ash from fumaroles inside the crater lake (e.g. daytime of 14 April, 10–12 June and 25 July 2005); emission of black ash from an almost dried-up vent (21 June 2005); and short-time (ca. 20 s) small-explosion-triggered gas-and-ash emission through the crater lake (10 July 2003, 14 January 2004 and 14 April 20h41m 2005). All products from these ash emissions consisted of fine-grained (< 1 mm) glass shards, crystals and lithic fragments, and contained neither lapilli nor blocks. Although the glass shards show varying degrees of crystallization and alteration, clear glass shards, which appear fresh, are probably juvenile materials. These observations suggest that the 2003–2005 ash emissions from the crater lake of Nakadake Volcano are related to newly ascending magma. 相似文献
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IntroductionSince the magnitude-frequency relation (1)being proposed and applied to the research of global seismicity by Gutenberg and Richter (1944, 1954), it has been widely used in the practice of seismic hazard prediction and of the research of seismic activity in different tectonic regions of the world ((1) is normally known as the G-R law).While with the increase of observational data of events, much researches show that though (1) can fit data well for events with middle value of magn… 相似文献
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Introduction With rapid development of national economy, urbanization has been speeded up in China, and several city groups or city belts with extra-large cities as their centers have been formed. For example, Pearl River Delta urbanized area surrounds Guangzhou City, Shenzhen City, Zhuhai City; Yangtze River Delta urbanized area surrounds Shanghai City, Suzhou City, Wuxi City, Nanjing City, Hangzhou City; Beijing-Tianjin-Tangshan urbanized area surrounds Beijing City, Tianjin City… 相似文献
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According to the epicenter distance and the site classification, the 404 groups of earthquake recordings of the main shock of the Chi-Chi, Taiwan China earthquake in 1999 are catalogued. Based on these data, we analyze the statistical features of duration, PGA, envelopes and the response spectra ratio of the horizontal and vertical components of the acceleration recordings. The results of these analyses show that the effect of site classification on the acceleration of various components is obvious; furthermore, fault direction also has certain effects on the characteristics of the horizontal components of ground motion. The detailed research results are as follows： （ 1 ） the duration of the horizontal components of acceleration records increases with the softening of the site; （2） the direction of fault slip has some effects on PGA＇s attenuation features; （3） the average envelopes of acceleration records at different distances and site dames are basically single peak functions of time and the envelopes of horizontal and vertical components of ground motion are obviously different; （4） with the same epicenter distance, EW/NS response spectrum ratios tend to approximate 1.0 as the site becomes softer and the period shorter. V/H response spectrum ratios in short periods （〈 0. 1s） increase with the softening of site, however, V/H ratios within the long-period range （ 〉 characteristic period） decrease with the softening of the site, and the decrease of V/EW ratio speeds up relatively. 相似文献
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Aiming Lin Mikako Sano Maomao Wang Bing Yan Di Bian Ryoji Fueta Takashi Hosoya 《Journal of Seismology》2017,21(4):683-703
The Mw 6.2 (Mj 6.8) Nagano (Japan) earthquake of 22 November 2014 produced a 9.3-km long surface rupture zone with a thrust-dominated displacement of up to 1.5 m, which duplicated the pre-existing Kamishiro Fault along the Itoigawa–Shizuoka Tectonic Line (ISTL), the plate-boundary between the Eurasian and North American plates, northern Nagano Prefecture, central Japan. To characterize the activity of the seismogenic fault zone, we conducted a paleoseismic study of the Kamishiro Fault. Field investigations and trench excavations revealed that seven morphogenic paleohistorical earthquakes (E2–E8) prior to the 2014 Mw 6.2 Nagano earthquake (E1) have occurred on the Kamishiro Fault during the last ca. 6000 years. Three of these events (E2–E4) are well constrained and correspond to historical earthquakes occurring in the last ca. 1200 years. This suggests an average recurrence interval of ca. 300–400 years on the seismogenic fault of the 2014 Kamishiro earthquake in the past 1200 years. The most recent event prior to the 2014 earthquakes (E1) is E2 and the penultimate and antepenultimate faulting events are E3 and E4, respectively. The penultimate faulting event (E3) occurred during the period of AD 1800–1400 and is associated with the 1791 Mw 6.8 earthquake. The antepenultimate faulting event (E4) is inferred to have occurred during the period of ca. AD 1000–700, likely corresponding to the AD 841 Mw 6.5 earthquake. The oldest faulting event (E8) in the study area is thought to have occurred during the period of ca. 5600–6000 years. The throw rate during the early Holocene is estimated to be 1.2–3.3 mm/a (average, 2.2 mm/a) with an average amount of characteristic offset of 0.7–1.1 m produced by individual event. When compared with active intraplate faults on Honshu Island, Japan, these slip rates and recurrence interval estimated for morphogenic earthquakes on the Kamishiro Fault along the ISTL appear high and short, respectively. This indicates that present activity on this fault is closely related to seismic faulting along the plate boundary between the Eurasian and North American plates. 相似文献
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Sotnikov N. V. Antonova E. E. Ryazantseva M. O. Barinova V. O. Rubinshtein I. A. Mit’ S. K. 《Geomagnetism and Aeronomy》2019,59(2):136-146
Geomagnetism and Aeronomy - This paper studies the position of the trapping boundary of electrons with energies of >100 keV relative to the equatorial boundary of the auroral oval during a... 相似文献
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Introduction With rapid development and advancement of economy and society, lots of city groups or city belts with ex-tra-large cities as their centers have been formed in China. The regions these city groups lie in usually have well-developed economy, dense population, and are regional politics and culture centers. Some groups lie in the regions with high level of earthquake activity, such as the Surrounding Capital City Group with the centers of Bei-jing and Tianjin. Once a large earthqua… 相似文献
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Jianjun Zhang Chuanlong Mou Chendong Liu Yong Zhang Ting Chen Hualiang Li 《Acta Geochimica》2024,(1):40-58
Geochemistry, zircon U–Pb geochronology, and Hf isotope data for the Early Paleozoic granites in the Baoshan Block reveal the Early Paleozoic tectonic evolution of the Proto-Tethys. The samples are high-K, calcalkaline, strongly peraluminous rocks with A/CNK values of 1.37–1.46, are enriched in SiO2, K2O, and Rb, and are depleted in Nb, P, Ti, Eu, and heavy rare earth elements,which indicates the crystallization fractionation of the granitic magma. Zircon U–Pb dating indica... 相似文献
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We analyzed sea level data from a set of tide gauge stations located in the central and western Mediterranean Sea, that recorded the tsunami generated by the Mw 6.8 Boumerdès earthquake striking the coast of Algeria on May 21, 2003. This earthquake caused more than 2200 victims and thousands of injured. The causative fault was located a few kilometers offshore and during the rupture a tsunami was triggered. Waves were felt along a large part of the western and northern Mediterranean coasts, and in the Balearic islands waves higher that 2 m were measured. In this paper we analyze a more complete tidal data set, with respect to previous studies, now consisting of 22 tidal stations located in Italy, France and Spain. To characterize the change of the tidal signal at each station we used the Empirical Mode Decomposition (EMD). By means of this technique, which is suitable to analyze and to characterize the dynamical behavior of non-stationary time series, we provide a precise measurement of the arrival times and amplitudes at the tidal stations and identify how this tsunami affected the principal and long term tidal components. Our findings improve previous results for this earthquake, since they allow the detection of significant amplitude fluctuations associated with the tsunami in the majority of stations, including the farthest ones. 相似文献
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V. K. Roldugin 《Geomagnetism and Aeronomy》2013,53(2):157-165
Thirty-six cases of Pc5 geomagnetic pulsations on the GOES-8 geostationary satellite for 2001, which had amplitudes equal to several nanoteslas and continued for more than an hour, have been studied. Twenty-two and 14 pulsations were toroidal and poloidal, respectively. All these pulsations were compared with geomagnetic observations at the Poste-de-la-Baleine observatory (PBQ), which was located near the satellite projection. It was established that the pulsation frequencies on the ground and in the magnetosphere do not always coincide. It has been detected that poloidal oscillations have small and large amplitudes on the ground and in the magnetosphere, respectively; the situation is opposite for toroidal oscillations. The amplitude of ground-level pulsations to a larger degree depends on the azimuthal field component in the magnetosphere than on the radial component. 相似文献
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《Journal of Atmospheric and Solar》1999,61(1-2):167-180
In just a few years the Internet has become an essential element in national and international science endeavors. Transfer of data, models, and related software across the net has skyrocketed. Interactive WorldWideWeb modules let the users do everything from simply specifying time periods for data retrieval to plotting complex data sets, to computing model parameters and to finding magnetic conjunctions between points in space. This paper reviews Internet sources for solar-terrestrial data and models, with special emphasis on systems that are related to, or a result of, the Solar Terrestrial Energy Program (STEP). We also discuss on-line systems that provide specific interactive services to the research community, like data finding, viewing, and browsing capabilities, comparison with model parameters, etc. This html document provides links to a large number of WWW sites that might be of interest for STEP research. It does not attempt to be a comprehensive guide to such sites but rather to provide access to selected typical sites for the specific capabilities discussed. Throughout the paper Universal Resource Locator (URL) addresses are highlighted in italics; the links to all the services mentioned are available on the WWW at http://nssdc.gsfc.nasa.gov/space/STEP-links.html. 相似文献