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1.
Sobolev G. A. Zakrzhevskaya N. A. Migunov I. N. Sobolev D. G. Boiko A. N. 《Izvestiya Physics of the Solid Earth》2020,56(3):291-315
Izvestiya, Physics of the Solid Earth - Abstract—The response of seismic noise in the minute range of periods to the strong magnetic storms is studied. The noise is analyzed from the records... 相似文献
2.
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
3.
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
4.
A. Ya. Sidorin 《Seismic Instruments》2011,47(4):368-385
The main features of periodic changes in the parameters of seismic noise, seismicity and electric power consumption in industrial
networks are compared to verify the hypothesis on the technogenic influence of electric network load on seismic noise and
seismicity and to search for possible origins of the diurnal periodicity in seismic emission processes discovered in various
regions of the world. Sufficiently good similarity of the compared processes is revealed that does not contradict the hypothesis.
However, there are also some important discrepancies. An inverse phase pattern of interdiurnal distributions of weak and strong
Japanese earthquakes has been found, and various possible mechanisms of this phenomenon, which had been observed earlier in
certain other regions, are discussed. 相似文献
5.
We examined the seismic activity which preceded six strong mainshocks that occurred in the Aegean (M?=?6.4–6.9, 33–43° N, 19–28° E) and two strong mainshocks that occurred in California (M?=?6.5–7.1, 32–41° N, 115–125° W) during 1995–2010. We find that each of these eight mainshocks has been preceded by a pronounced decelerating and an equally easily identifiable accelerating seismic sequence with the time to the mainshock. The two preshock sequences of each mainshock occurred in separate space, time, and magnitude windows. In all eight cases, very low decelerating seismicity, as well as very low accelerating seismicity, is observed around the actual epicenter of the ensuing mainshock. Statistical tests on the observed measures of decelerating, q d, and accelerating, q a, seismicity against similar measures calculated using synthetic catalogs with spatiotemporal clustering based on the ETAS model show that there is an almost zero probability for each one of the two preshock sequences which preceded each of the eight mainshocks to be random. These results support the notion that every strong shallow mainshock is preceded by a decelerating and an accelerating seismic sequence with predictive properties for the ensuing mainshock. 相似文献
6.
The traces of strong earthquakes in the territory of Fennoscandia have been recorded by many scientists already for several decades. The seismogenerating paleostructures, such as postglacial discontinuities in the crystalline basement accompanied by a complex of deformations in the loose deposits are found in the territories of Sweden, Norway, and Finland that border Russia, in which case the spatial correlation of the postglacial faults and modern seismicity is established. Such structures have not yet been discovered in Russia, though the traces of strong earthquakes in the form of rock deformations and postglacial sediments are found by different groups of researchers over the whole territory of Eastern Fennoscandia. The obtained data make it possible to identify the linear zones of concentration of paleoearthquakes (seismic lineaments) that also occur in the modern relief and modern seismicity. However, the problem of postglacial seismicity remains a subject for discussions concerning the localization of the foci, their genesis, and regime. A remaining issue is also distinguishing between seismogenic, cryogenic, and glaciodislocations. The important questions that need to be solved include parametrization of paleoearthquakes and determination of their nature, structures, age, and magnitude. One of the key segments is the area of Vottovaara Mountain in Middle Karelia, which is a part of the Vottovaara–Girvas seismic lineament, where seismic dislocations were found earlier. For studying this probable paleo-focal zone in detail, remote sensing data, field geological and geomorphological observations, and computational methods for estimating the peak values of paleoearthquake mass velocities are used. The typical zones of development of different types of seismic deformations are revealed. A potential seismogenerating fault related to the northwest-striking Vottovaara–Girvas seismic lineament is found; its probable shear kinematics is determined from the ratio of pulse displacements of rock blocks on different wings of the fault. The sequence of a few strong events which occurred here in the interglacial and postglacial periods is identified. The effects of interaction between the seismic activity and the glacial exaration on the formation of the modern image of the focal zone are established. Using alternative approaches to estimating shaking intensity by the macroseismic INQUA scale, the scale by F.F. Aptikayev, and the nomogram by M.V. Rodkin, the intensity of the recent strong Early Holocene seismic event, which occurred here at 8.9 ka according to A.D. Lukashov, is determined. According to the agreed estimates, the intensity reached 9–10 points at a probable magnitude of 7.5–8. This work carried out using a number of new approaches developed by the authors makes it possible to characterize paleoseismicity in more detail. 相似文献
7.
8.
中国大陆邻区的地震活动和中国大陆地震的关系 总被引：1，自引：0，他引：1
研究了３个方面的问题，一是中国大陆周边４个地震带地震活跃期与中国大陆地震活跃期的准同步性和它们目前的活动水平；二是欧亚地震带西部与中国大陆的地震活动呈出现明显的超前或滞后性；三是中国大陆邻区６个地震区的强震与中国大陆活跃期的开始或与中国大陆强震的对应关系。 相似文献
9.
The results of long-term studies of seismic noise before strong regional earthquakes on the Kamchatka Peninsula in 1992–2006 are presented. These results show that parameters of seismic noise variations caused by the tidal effect depend on the source position of the forthcoming earthquake. The reproducibility of the observed effects is demonstrated by the example of two strong deep (～200 km) subduction earthquakes with similar parameters that occurred on June 16, 2003 (M = 6.9), and on June 10, 2004 (M = 6.8). The physical mechanism of the synchronization of the tidal component extracted from high-frequency seismic noise with the wave of the gravitational tidal potential can be related to the possible development of near-surface dilatancy zones. 相似文献
10.
G. A. Sobolev N. A. Zakrzhevskaya D. G. Sobolev V. A. Petrov 《Journal of Volcanology and Seismology》2017,11(2):103-112
This study is concerned with the influence exerted by worldwide M ≥ 7.5 earthquakes on the seismicity of California, and well as with the effects of M ≥ 5 southern California earthquakes on northern Californian seismicity. The analysis concerns the 1990–2013 period. We noted a seismicity increase in southern and northern California during the first 24 hours after worldwide earthquakes and a decrease during the next 48 hours. A seismicity increase in northern California during the first 24 hours following an earthquake in southern California and a decrease during the next 48 hours were also noted. A seismicity increase was observed in the Long Valley caldera during the first 24 hours following an M ≥ 5 earthquake in southern California and a decrease during the next 48 hours. We also discuss some causes of this trigger effect, in view of the fact that the external excitations had low intensity. No seismicity changes have been detected in southern and northern California during powerful typhoons in the northeastern Pacific and during magnetic storms. 相似文献
11.
川滇藏邻区巴塘——丽江地震块体强震活动特征的初步探讨 总被引：4，自引：0，他引：4
本根据１９８６￣１９９６年川滇藏三省（区）邻界区巴塘－丽江－带频繁的强震活动的资料,结合活动构造带分布及历史强震记录,分析了该邻界区强震活动若干特征,提出了“存在川滇藏邻界区巴塘－丽江地震块体”的认识,并就其与相邻地区强震活动关系及未来强震趋势作了讨论。 相似文献
12.
The annual number of magnetic storms N recorded at St. Petersburg observatories (Pavlovsk/Slutsk and Voyeykovo) in 1878–1954 is studied. The analysis shows that N has increased since ~1900 for different storm types (storms with sudden commencement Ssc and storms with gradual Sg commencement; moderate, strong and very strong); however, the number of Ssc storms increased more rapidly than the number of Sg storms. The percentage of Ssc storms doubled for the first half of the 20th century, while the number of Sg storms decreased by 1.5 times. The Ssc storms are driven by coronal mass ejections from closed magnetic structures on the Sun, and Sg storms are driven by corotating fluxes from open magnetic structures and coronal holes. These results are apparently evidence of an increase in the activity of both types of solar magnetic structures in the first half of the 20th century and a more rapid increase in the activity of fields with closed lines of forces. A semiannual variation with maxima in the periods of vernal and autumnal equinoxes is clearly pronounced for Sg and moderate storms. The tendency to have two equinoctial maxima is pronounced in the total number of storms N for both even and odd cycles; however, maxima that differ from the arithmetic mean by more than a standard deviation are observed only in September in even cycles and in March in odd cycles. 相似文献
13.
We investigate the relationship between the impoundment and seismicity in the Longtan reservoir, southwestern China and find evidence that the seismicity was reservoir induced. After the reservoir impoundment, a pronounced increase in seismicity was observed in five clusters mainly concentrated in the areas where few earthquakes had occurred before the first filling. The observed induced seismicity shows a strong correlation with the filling cycles. The activity levels in the five clusters are different due to differences in the structures and permeabilities of the faults. Source parameters for 1,616 earthquakes with M L 0.1–4.2 recorded by 24 fixed and temporary stations deployed around the reservoir were calculated after applying corrections for geometrical spreading, frequency-dependent Q, and site effects. The static stress drop and apparent stress in this area both appear to increase with increasing seismic moment over the entire magnitude range. Our results show that reservoir induced earthquakes have ten times lower average stress drop than natural tectonic earthquakes. These results may indicate that the reservoir induced seismicity can occur with a lower tectonic stress due to the high pore pressures of the underground medium, and that the effect of the water decreases the coefficient of friction. 相似文献
14.
2021年第6号台风“烟花”是2021年度对江苏地区影响最强烈的台风。地震台站台基噪声是影响观测质量的关键因素,为了探究台风“烟花”对江苏地区地震台站台基噪声的影响,利用江苏地震台网2021年7月1日至8月3日记录的连续波形数据,通过计算波形自相关函数卓越周期与台基噪声水平的速度均方根有效振幅(RMS),研究其与台风参数之间的关系。结果表明：①在台风 “烟花”初始发育阶段,卓越周期由平时的2—4 s逐步上升到4—7 s,随着台风影响范围逐渐向陆地转移,卓越周期缓慢降低,随着台风完全登陆并不断减弱,卓越周期又恢复到正常水平;②在台风“烟花”的整个进程中,绝大多数台站的RMS值变化幅度不超过正常值的15%,各台站RMS值变化幅度在正常波动范围内。 相似文献
15.
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
16.
在地震学参量年度异常的背景＾（３）,阐述了１９９５￣１９９６年云南地区发生的孟连、武定、丽江三次强震前的地震活动短期异常,包括地震平静、小震群、窗口地震、调制地震、地震波参数以及４级左右地震向震中迁移等。结果表明,这些异常特征表现突出,其演化进程显示了强震孕育的阶段性。 相似文献
17.
大同—阳高6.1级地震活动背景 总被引：1，自引：0，他引：1
本文从较大时空范围研究了１９８９年大同－阳高６．１级地震的地震活动性背景，认为大同－阳高地震不是一次孤立的地震事件，是大同盆地历史６级以上地震活动的继续和必然。在时间进程中它们受华北地震区和山西地震带强震活动周期的制约，空间上与北三省交汇区中强地震成丛活动密切相关。大同－阳高６．１级、５．８级地震以及此期间的侯马４．９级、析州５．１级地震是山西地震带中强地震即将活跃的一个迹象，也是华北区域应力场增 相似文献
18.
R. Maresca L. Nardone G. Pasquale F. Pinto F. Bianco 《Pure and Applied Geophysics》2012,169(7):1173-1188
The effects of surface geology on ground motion provide an important tool in seismic hazard studies. It is well known that the presence of soft sediments can cause amplification of the ground motion at the surface, particularly when there is a sharp impedance contrast at shallow depth. The town of Avellino is located in an area characterised by high seismicity in Italy, about 30?km from the epicentre of the 23 November 1980, Irpinia earthquake (M?=?6.9). No earthquake recordings are available in the area. The local geology is characterised by strong heterogeneity, with impedance contrasts at depth. We present the results from seismic noise measurements carried out in the urban area of Avellino to evaluate the effects of local geology on the seismic ground motion. We computed the horizontal-to-vertical (H/V) noise spectral ratios at 16 selected sites in this urban area for which drilling data are available within the first 40?m of depth. A Rayleigh wave inversion technique using the peak frequencies of the noise H/V spectral ratios is then presented for estimating Vs models, assuming that the thicknesses of the shallow soil layers are known. The results show a good correspondence between experimental and theoretical peak frequencies, which are interpreted in terms of sediment resonance. For one site, which is characterised by a broad peak in the horizontal-to-vertical spectral-ratio curve, simple one-dimensional modelling is not representative of the resonance effects. Consistent variations in peak amplitudes are seen among the sites. A site classification based on shear-wave velocity characteristics, in terms of Vs30, cannot explain these data. The differences observed are better correlated to the impedance contrast between the sediments and basement. A more detailed investigation of the physical parameters of the subsoil structure, together with earthquake data, are desirable for future research, to confirm these data in terms of site response. 相似文献
19.
基于多用户峰度准则的海洋强噪声衰减方法(英文) 总被引：1，自引：1，他引：0
海洋地震勘探过程中,由于采集设备的老化或电源的不稳定而造成的漏电,在地震记录表现为强噪音干扰,利用常规噪音衰减方法处理此类强噪音效果并不理想。鉴于强噪音在统计学上具有相同的特性,本文在基于峰度的盲分离(blind source separation,BSS)算法研究基础上,推导出一种基于多用户峰度(multiuser kurtosis,MUK)准则的噪音衰减算法来估计地震记录中具有相同统计特性的强噪音,并将其从地震记录中分离,从而达到衰减强噪音的目的。模型试验与实际资料的处理表明:该方法能够在好的衰减海洋地震勘探记录中的强噪音,保留了更多的有效信息,提高海洋地震数据的信噪比,具有可行性和应用前景。 相似文献
20.
J. Almendros J. M. Ibez G. Alguacil J. Morales E. Del Pezzo M. La Rocca R. Ortiz V. Araa M. J. Blanco 《Journal of Volcanology and Geothermal Research》2000,103(1-4)
Data analyzed in the present work correspond to a 40 days field experiment carried out in Teide Volcano (Canary Islands, Spain) with two short-period small-aperture dense seismic antennas in 1994. The objective of this experiment was to detect, analyze and locate the local seismicity. We analyzed also the background seismic noise to investigate the possible presence of volcanic tremor. From a set of 76 events, we selected 21 of them in base of their good signal-to-noise ratio and their possibility to locate their seismic source by using the seismic antennas. A visual classification based on the S–P time and seismogram shape has permitted to establish three groups of events: local seismicity (S–P time between 3 and 5 s), very local earthquakes (S–P time smaller than 3 s) and artificial explosions. These earthquakes have been located by applying the Zero Lag Cross-Correlation technique and the inverse ray-tracing procedure. Those earthquakes that were recorded simultaneously by both seismic antennas were also located by intersecting both back-azimuths. The analysis of the seismicity has revealed that the amount of seismicity in Teide Volcano is moderate. This seismicity could be distributed in three main areas: inside the Caldera Edifice (below the Teide–Pico Viejo complex), in the eastern border of the Caldera Edifice and offshore of the island. At present, this activity is the only indicator of the volcano dynamics. The analysis of the back-ground seismic noise has revealed that at frequencies lower than 2 Hz, the Oceanic Load signal is predominant over other signals, even over local earthquakes with a magnitude of 2.0. Due to this, although if in the Teide area were present a weak volcanic tremor, or other volcanic signals with predominant peaks below 2 Hz, to observe them would be a very difficult task. 相似文献