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1.
本文利用地震活动性指数 A(b)对本世纪初以来的全球地震活动性作定量的研究,着重探讨全球地震活动随时间的变化.根据求 A(b)指数的结果,对阿部胜征和巴特、杜达的两种不同的世界地震目录作了对比分析.本世纪的全球地震活动总趋势是一种有起伏的衰减.全球深震和浅震活动水平分别在1950-1952年和1952-1955年有一个显着的下降,使得后半世纪的浅震活动水平普遍降低了0.3左右,浅震和深震的总体水平下降了0.2左右.浅震和深震的总体变化幅度小于二者的相对变化幅度.1959年以后,相对变化的成分十分显着. 相似文献
2.
Seismicity of the southern Siberian platform: Spatiotemporal characteristics and genesis 总被引：1，自引：0，他引：1
Analysis of instrumental data on earthquakes of 1960–2005 in the Irkutsk amphitheater shows that the majority of the earthquakes form a wide (150–300 km) band of diffuse seismicity along the marginal suture of the Siberian platform. In accordance with established regular spatiotemporal patterns of the distribution of earthquakes, this band belongs to the Sayan-Baikal seismic belt, associated with the destruction process at the boundary of large lithospheric blocks. The band is located on the northern periphery of the belt and, the deformable substrate being highly monolithic, this sharply weakens the seismicity within the band. Because of the tectonic origin of earthquakes in such a vast platform territory, undoubted evidence for induced seismicity around the Angara cascade reservoirs, and the intense economic development of the region, the problem of seismic hazard in the southern Siberian platform should be regarded as one of the most significant objects of geodynamic research. 相似文献
3.
ＭａｘｉｍｕｍｅｎｔｒｏｐｙｓｐｅｃｔｒａｌｃｈａｒａｃｔｅｒｉｓｔｉｃｓｏｆｓｅｉｓｍｉｃａｃｔｉｖｉｔｙｆｏｒｇｒｅａｔｅａｒｔｈｑｕａｋｅｓｉｎＣｈｉｎａＺＨＩＰＩＮＧＳＯＮＧ１）（宋治平）ＳＨＩＲＯＮＧＭＥＩ２）（梅世蓉）ＡＮＸＵＮＷ... 相似文献
4.
D. Shanker H. N. Singh H. Paudyal A. Kumar A. Panthi V. P. Singh 《Pure and Applied Geophysics》2010,167(6-7):655-666
A long-range correlation between earthquakes is indicated by some phenomena precursory to strong earthquakes. Most of the major earthquakes show prior seismic activity that in hindsight seems anomalous. The features include changes in regional activity rate and changes in the pattern of small earthquakes, including alignments on unmapped linear features near the (future) main shock. It has long been suggested that large earthquakes are preceded by observable variations in regional seismicity. Studies on seismic precursors preceding large to great earthquakes with M ≥ 7.5 were carried out in the northeast India region bounded by the area 20°–32°N and 88°–100°E using the earthquake database from 1853 to 1988. It is observed that all earthquakes of M ≥ 7.5, including the two great earthquakes of 1897 and 1950, were preceded by abnormally low anomalous seismicity phases some 11–27 years prior to their occurrence. On the other hand, precursory time periods ranged from 440 to 1,768 days for main shocks with M 5.6–6.5 for the period from 1963 to 1988. Furthermore, the 6 August, 1988 main shock of M 7.5 in the Arakan Yoma fold belt was preceded by well-defined patterns of anomalous seismicity that occurred during 1963–1964, about 25.2 years prior to its occurrence. The pattern of anomalous seismicity in the form of earthquake swarms preceding major earthquakes in the northeast India region can be regarded as one of the potential seismic precursors. Database constraints have been the main barrier to searching for this precursor preceding smaller earthquakes, which otherwise might have provided additional information on its existence. The entire exercise indicates that anomalous seismicity preceding major shocks is a common seismic pattern for the northeast India region, and can be employed for long-range earthquake prediction when better quality seismological data sets covering a wide range of magnitudes are available. Anomalous seismic activity is distinguished by a much higher annual frequency of earthquake occurrence than in the preceding normal and the following gap episodes. 相似文献
5.
Yu. A. Kugaenko N. M. Kravchenko V. A. Saltykov 《Journal of Volcanology and Seismology》2009,3(3):168-178
We report extensive anomalies identified in seismicity parameters at different energy levels which were observed during the precursory process of the Karymskii seismovolcanic crisis of January 1–2, 1996. The seismicity of different energies includes earthquakes contained in the Kamchatka regional catalog and seismic noise (amplitudes of 10?9–10?12 m, frequencies of a few tens of hertz), which is a manifestation of the seismic process in the lowest energy range. The parameters of background seismicity are considered in retrospect using techniques for analyzing the dynamics of the seismic process: RTL and the Z function. Microseismicity is examined using these authors’ own method based on monitoring the response of high frequency seismic noise to tidal excitation 相似文献
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G. A. Sobolev 《Journal of Volcanology and Seismology》2007,1(3):198-211
Premonitory phases (seismic quiescence and foreshock activity) have been retrospectively identified before the Neftegorsk and Uglegorsk earthquakes using the RTL technique. The probabilities that these phases were accidental are less than 1 and 2%, respectively. This allows an optimistic assessment of the possibility of applying this technique to seismicity at Sakhalin. The estimates of the time and energy class for the two earthquakes, using a model of self-organized seismic criticality, proved to be unconvincing because obvious acceleration of the seismic process prior to these seismic events did not occur. The applicability of this approach to the seismicity at Sakhalin should be tested for future large earthquakes. The regional Sakhalin catalog for 1980–2000, with a lowest completely reported energy class of K = 8 (lent by the Geophysical Service, Russian Academy of Sciences) was used as the database for this study. 相似文献
8.
V. I. Ulomov T. I. Danilova N. S. Medvedeva T. P. Polyakova L. S. Shumilina 《Izvestiya Physics of the Solid Earth》2007,43(7):559-572
The seismicity of the North Caucasus is the highest in the European part of Russia. The detection of potential seismic sources here and long-term prediction of earthquakes are extremely important for the assessment of seismic hazard and seismic risk in this densely populated and industrially developed region of the country. The seismogenic structures of the Iran-Caucasus-Anatolia and Central Asia regions, adjacent to European Russia, are the subjects of this study. These structures are responsible for the specific features of regional seismicity and for the geodynamic interaction with adjacent areas of the Scythian and Turan platforms. The most probable potential sources of earthquakes with magnitudes M = 7.0 ± 0.2 and 7.5 ± 0.2 in the North Caucasus are located. The possible macroseismic effect of one of them is assessed. 相似文献
9.
Yan B. Radziminovich 《Journal of Seismology》2014,18(1):93-107
The parametric catalogues of historical earthquakes in East Siberia contain large data gaps. Among these is a 15-year period in the late nineteenth century (1886–1901). This period was not covered by any of macroseismic catalogues known; neither acquisition nor systematization of macroseismic data was ever performed for that purpose. However, 15 years is a rather long period in which large seismic events may have occurred. The present paper deals with the previously unknown earthquake that occurred on November 13, 1898. The primary macroseismic data were taken from regional periodicals. On the strength of all the evidence obtained, the earthquake epicenter is localized in Western Transbaikalia, near the western end of the Malkhansky Range; the magnitude is estimated at M?=?5.9. The information about the large earthquake of November 13, 1898 provides filling significant gaps in knowledge for seismicity in Western Transbaikalia and a better understanding of seismic potential of faults therein. The obtained results show that the periods of seismic quiescence in catalogues may be related to insufficient information on seismicity of Eastern Siberia in the historical past rather than to the absence of large earthquakes. 相似文献
10.
The responses of the Kamchatka earthquakes with a minimum energy class of completeness K ≥ 8.5 to 214 strong worldwide earthquakes with magnitudes M ≥ 7.5 and to 40 earthquakes with M ≥ 8 are studied. The analysis covers the time interval of 1963–2012. The distances from the sources of the strongest earthquakes to the center of the seismically active Kamchatka zone range from 600 to 16000 km. It is established that the remote earthquakes enhanced seismic activity in Kamchatka, at least in the cases when the dynamic strain was above 10?6, which corresponds to the additional stresses of 10?2 MPa, accelerations above 0.1 cm/s2, and the periods of the surface waves of ～20 s. The response to the remote events gradually increased within a few days. The sensitivity of the response to the remote earthquakes varied in the course of time, which is identified on the intervals of a few dozens of years. 相似文献
11.
The seismic regime taking place before the Tohoku mega-earthquake was studied using the catalog of the Japan Meteorological Agency (JMA). We show that the Tohoku earthquake was preceded by a 6–7-year period of regional reduction in the b-value and in the rate of main shocks. The space-time regions that involved precursory activation were nearly identical with the predictive phenomena that were previously detected by A.A. Lyubushin from an analysis of seismic noise based on data from the Japanese F-net. We discovered a previously unknown effect of correlation between the number of main shocks and the b-value. Both the ordinary foreshock activation and the longer weaker tendency, which consist in a precursory increase in the seismicity rate, were identified in the vicinities of M ≈ 7 Japanese earthquakes (similarly to the seismicity in the Generalized Vicinities of large earthquakes based on worldwide data). 相似文献
12.
１９９４年全球地震活动属于高水平，有４次大深震和４次浅源大地震。全球全年共发生６级以上地震１３４次，超过１９９３年。全球地震活动中心仍在太平洋西北边缘地震带。１０月４日的千岛群岛地震是最大的浅源地震；６月９日的玻利维亚地震是最大的深源地震。１９９４年全球地震活动开始转折，揭开强烈活动期的序幕。各大地震带的Ａ（ｂ）值几乎按同一比例上升，显示全球地震整体性增强。全球地震Ａ（ｂ）值在６月和１０月有两次高 相似文献
13.
The interpretation of the nature and parameters of the source for the earthquake that occurred in Sumatra on December 26, 2004 is suggested. Our study relies on a variety of data on the geological structure of the region, long-term seismicity, spatial distribution of the foreshocks and aftershocks, and focal mechanisms; and the pattern of shaking and tsunami, regularities in the occurrence of the earthquakes, and the genetic relationship between the seismic and geological parameters inherent in various types of seismogenic zones including island arcs. The source of the Sumatran earthquake is a steep reverse fault striking parallel to the island arc and dipping towards the ocean. The length of the fault is ～450 km, and its probable bedding depth is ～70–100 km. The magnitude of this seismic event corresponding to the length of its source is 8.9–9.0. The vertical displacement in the source probably reached 9–13 m. The fault is located near the inner boundary of the Aceh Depression between the epicenter of the earthquake and the northern tip of the depression. The strike-slip and strike-slip reverse the faults cutting the island arc form the northern and southern borders of the source. The location and source parameters in the suggested interpretation account quite well for the observed pattern of shaking and tsunami. The Aceh Depression and its environs probably also host other seismic sources in the form of large reverse faults. The Sumatran earthquake, which was the culmination of the seismogenic activation of the Andaman-Sumatra island arc in the beginning of XXI century, is a typical tsunamigenic island-arc earthquake. By its characteristics, this event is an analogue to the M W = 9 Kamchatka earthquake of November 4, 1952. The spatial distribution of the epicenters and the focal mechanisms of the aftershocks indicate that the repeated shocks during the Sumatran event were caused by the activation of a complex system of geological structures in various parts of the island arc and Andaman Sea instead of the slips on a single rupture (a subduction thrust about 1200–1300 km in length). 相似文献
14.
V. I. Ulomov 《Izvestiya Physics of the Solid Earth》2007,43(9):713-725
Substantial changes in the seismic regime of the Earth during 1982–1993 are revealed on the basis of a new methodological approach to the study of the development of global seismogeodynamic processes. These changes are a more than threefold decrease in the recurrence rate of large earthquakes in the magnitude intervals M = 8.5 ± 0.2, M = 8.0 ± 0.2, M = 7.5 ± 0.2, and M = 7.0 ± 0.2 and a very intense activation of global seismicity after this relative seismic quiescence. Joint investigations of seismogeodynamic and hydrogeodynamic processes allowed us to reveal a certain synchronism between changes in the seismic regime of the Earth and the ocean water surface level. In this paper, we continue the search for a relation between changes in the regional seismicity and the level of closed water basins (with the Caspian Sea as an example), as well as investigations of the processes in individual seismic sources, in order to elaborate earthquake prediction methods. Hypotheses on the nature of the discovered phenomena are put forward, and structural phenomenological models are proposed. In particular, these correlated seismic and hydrologic phenomena are interpreted in terms of specific features of the seismogeodynamic regime in subduction zones on the periphery of the Pacific and Indian oceans. 相似文献
15.
V. B. Smirnov R. K. Chadha A. V. Ponomarev D. Srinagesh 《Izvestiya Physics of the Solid Earth》2013,49(2):243-257
In 2000, the region of the Koyna-Warna water reservoirs in West India was hit by two strong earthquakes, which occurred six months apart and had magnitudes M > 5. The Koyna-Warna seismic zone is a typical region of induced seismicity with a pronounced correlation between seismicity and water level variations in the reservoirs. This indicates that the stress level in the region is close to critical; thus, insignificant variations in stress caused by the variations in the water level may trigger a strong earthquake. In order to study the preparatory processes in the sources of the induced earthquakes, in this paper we analyze the seismic catalogue for the Koyna-Warna region before a pair of strong earthquakes of 2000. The induced seismicity is found to exhibit prognostic variations, which are typical of preparation of tectonic earthquakes and indicative of the formation of metastable source zones of future earthquakes. Based on the obtained results, we suggest that initiation of failure in these metastable zones within the region of induced seismicity could have been caused by the external impacts associated with water level variations in the reservoirs and by the internal processes of avalanche unstable crack propagation. 相似文献
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At the beginning of the 21st century, a series of great earthquakes were recorded in northeastern Tibet, along the periphery of the Bayan Hara lithospheric block. An earthquake with MS = 8.1 occurred within the East Kunlun fault zone in the Kunlun Mountains, which caused an extended surface rupture with left-lateral strike slip. An earthquake with MS = 8 occurred in Wenchuan (China) on May 12, 2008, giving rise to an extended overthrust along the Lunmanshan fault zone. An earthquake with MS = 7.1 occurred in Yushu (China) on April 14, 2010; its epicenter was on the Grazze–Yushu–Funchuoshan fault; a left-lateral strikeslip offset was observed on the surface. An earthquake with MS = 7 occurred in the vicinity of Lushan on April 20, 2013; its epicenter was within the Lunmanshan fault zone, 103 km southwest of the zone of the catastrophic Wenchuan earthquake. An earthquake with MS = 8.2 occurred in Nepal on April 25, 2015. Based on the CSN seismic catalog, the energy of all earthquakes in eastern Tibet at the end of the 20th and beginning of the 21st centuries was estimated. It was found that Tibet was seismically quiet from 1980 to 2000. The beginning of the 21st century has been marked by seismic activation with earthquake sources migrating southward to surround the Bayan Hara lithospheric block from every quarter. Therefore, this block can be regarded as one of the most seismically active regions of China. 相似文献
18.
By analyzing the threshold levels of the triggering action, we quantitatively substantiate the changes in the energy of the triggering impact for the cases of the initiation of the lowand high-energy earthquakes depending on the seismic activity of the medium. The analysis is based on the data on the seismicity caused by the high-power electric pulses and geomagnetic field of the magnetic storms with sudden commencement. The analysis of the threshold levels of the triggering action indicates that the energy level required for triggering grows with the increase in the energy class of the earthquake. This is inconsistent with the facts of initiation of strong earthquakes by physical fields in the absence of evident high-energy sources of triggering. The probable explanation suggests that if the source of a strong earthquake is adjoined by local potential sources, the rupturing of one of the local potential sources caused by an energetically weak pulsed impact of the physical fields by the triggering scenario leads to the initiation of a strong earthquake. 相似文献
19.
我国东北和华北地区中强地震潜在震源区的划分原则和方法 总被引：18，自引：5，他引：18
中强地震潜在震源区的不确定性，对弱地震活动区地震危险性分析结果的影响较大。因此，正确二划分中强地震潜在震源区，是地震区划加和工程场地地震安全性评价的基础。本文以东北和华北地区为例，较为系统地整理了大量基础资料，从众多典型震例分析结果中提出了该地区中强地震潜在震源区的划分原则和方法，对长春，吉林等地区进行了实验划分结果表明，本文所提出了划分原则和方法具有较好的适应性。与此同时，还对本文取得的进展和有 相似文献
20.
V. G. Bakhmutov F. I. Sedova T. A. Mozgovaya 《Izvestiya Physics of the Solid Earth》2007,43(11):931-937
Based on the example of the Vrancea zone of concentrated seismicity, it is shown how the stress-strain state of the medium responds to a disturbance of the geomagnetic field. Geomagnetic conditions are examined in relation to earthquakes in the Vrancea zone in the period 1988–1996. It is established that the seismic energy release in the Vrancea zone is associated with differences (“gradients”) in the H component of the geomagnetic field. Such a gradient preceding earthquakes is shown to be the midnight polar substorm and the degree of its mid-latitude effect. The time interval from the maximum of the substorm development to a shock (τ, h) is directly related to the focal depth. The seismic characteristics K en and h (km) are demonstrated to be related to morphological features of the substorm development, namely, its duration T (min), intensity, and background. Differences in the duration of polar substorms before crustal (shallow) and deep earthquakes are revealed. Morphological features of the spectrum of geomagnetic variations preceding the seismic energy release are established. 相似文献