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1.
Wang Qiong 《中国地震研究》2007,21(3):255-268
The Bachu-Jiashi earthquake of Ms6.8 occurred on February 24, 2003, about 20km from the southeast of the 1997 - 1998 Jiashi seismic region in Xinjiang, and its aftershocks are rich and strong. Did the 1997 - 1998 Jiashi strong earthquake swarm trigger the Bachu-Jiashi Ms6.8 earthquake？ The Atushi earthquake of Ms6.7 occurred in 1996, and the 1997 - 1998 Jiashi strong earthquake swarm occurred about 70km from the Atushi earthquake 10 months later. Did the Atushi earthquake of Ms6.7 encourage the 1997 - 1998 Jiashi strong earthquake swarm？ There were 9 earthquakes with Ms6.0 from 1996 to 1997 in the Jiashi seismic region, how did they act on each other？ To answer the above questions, the article studies the triggering effect of the activity process of the whole Jiashi earthquake swarm from the 1996 Atushi earthquake of Ms6.7, the 1997 - 1998 Jiashi strong swarm to the 2003 Bachu-Jiashi earthquake of Ms6.8, and analyzes the seismicity characteristics around the Jiashi region. The results show that the 1996 Atushi earthquake of Ms6.7 encouraged the 1997 - 1998 Jiashi strong swarm to some extent, the accumulative Coulomb stress change from the previous M6.0 earthquakes of the Jiashi strong swarm had certain triggering effects on the following M6.0 events, and the Coulomb stress change converted from the Jiashi strong swarm strongly encouraged the 2003 Bachu-Jiashi earthquake with Ms6.8. 相似文献
2.
Smirnov V. B. Ponomarev A. V. Stanchits S. A. Potanina M. G. Patonin A. V. Dresen G. Narteau C. Bernard P. Stroganova S. M. 《Izvestiya Physics of the Solid Earth》2019,55(1):124-137
Izvestiya, Physics of the Solid Earth - Laboratory experiments on studying the aftershock regime are carried out on sandstone specimens at different levels of axial loading and uniform compression... 相似文献
3.
By using GDS dynamic hollow cylinder torsional apparatus, a series of cyclic torsional triaxial tests under complex initial consolidation condition are performed on Nanjing saturated fine sand. The effects of the initial principal stress direction α0, the initial ratio of deviatoric stress η0, the initial average effective principal stress p0 and the initial intermediate principal stress parameter b0 on the threshold shear strain y, of Nanjing saturated fine sand are then systematically investigated. The results show that y, increases as η0, P0 and b0 increase respectively, while the other three parameters remain constant. α0 has a great influence on y,, which is reduced when α0 increases from 0° to 45° and increased when α0 increases from 45° to 90°. The effect of α0 on γt plays a leading role and the effect of η0 will weaken when α0 is approximately 45°. 相似文献
4.
Effect of Initial Stress Conditions on the Threshold Shear Strain of Nanjing＇s Saturated Fine Sand 总被引：2，自引：0，他引：2
By using GDS dynamic hollow cylinder torsional apparatus,a series of cyclic torsional triaxial tests under complex initial consolidation condition are performed on Nanjing saturated fine sand. The effects of the initial principal stress direction α0,the initial ratio of deviatoric stress η0,the initial average effective principal stress p0 and the initial intermediate principal stress parameter b0 on the threshold shear strain γt of Nanjing saturated fine sand are then systematically investigated. The results show that γt increases as η0,p0 and b0 increase respectively,while the other three parameters remain constant. α0 has a great influence on γt,which is reduced when α0 increases from 0° to 45° and increased when α0 increases from 45° to 90°. The effect of α0 on γt plays a leading role and the effect of η0 will weaken when α0 is approximately 45°. 相似文献
5.
The focal mechanisms of events from three micro-earthquake swarms (swarm in the years 1985/86, swarm of December 1994, and swarm of January 1997) in the epicentral area of Nový Kostel (West Bohemia region) were used as input data for stress analyses. The simple graphical method of Angelier and Mechler (1977) and inversion by the program BRUTE3 (Hardcastle and Hills, 1993) were applied to the data collections. The results of the stress analyses for the 1985/86 swarm and for the swarm of December 1994 are similar. For the January 1997 swarm, the results of the analyses differ from those for older swarms. The axis of maximum extension is oriented in the NE-SW direction and is subhorizontal, the axis of maximum compression is oriented in the NW-SE direction and perspicuously dips towards SE. These results are similar to older results of stress analyses carried out for the 1985/86 swarm (Antonini, 1988; Sonnleitner,1993). They are also consistent with most of other published results of stress analyses conducted at different sites in the western part of the Bohemian Massif. The orientation of the principal stresses confirms the sinistral strike-slip movement along the Nový Kostel-Poátky-Zwota line (the trend is about 355°) defined by the epicentres of the micro-earthquakes. The eastern tectonic limit of the Cheb Basin (and other respective parallel faults ) could be characterised by normal rather than strike-slip faulting. 相似文献
6.
Gao Guoying 《中国地震研究》2007,21(4):397-408
Jiashi and its surrounding areas are composed of many structural zones. Using the focal mechanism solutions of 59 moderately strong earthquakes in Jiashi and its surrounding areas, and combining these with the calculation results of system cluster and stress field inversion, we analyzed the evolvement characteristics of the stress field for different times and different regions. The results were as follows: The earthquakes in Jiashi are mainly strike-slip. However, those of the Kalpin block are mainly reverse events, showing an obvious thrusting. The regional characteristics are different from other areas. The direction of the regional principal stress field is near NS. However, under different tectonic backgrounds, the directions of the stress fields are different. The direction of the principal compress stress is near NS in the Kashi-Wuqia area. But before and after the 3 earthquakes with M7.0, dynamic evolution from NW to NS and then to NE with time process was observed. The Kalpin block has been dominated by a consistent stress field in the NW direction for a long time. However, the direction of the stress field of the Jiashi region is NE. Since 1996, the direction of the regional stress field has changed obviously. The direction of the P axis was deflected towards the NE, and the plunge angle increased. The result shows clearly the regional characteristics and variation of the distribution pattern of the stress field in different tectonic environments. 相似文献
7.
Xu Wenjun Zhao Weiming Chai Chizhang Jin Yanlong Sun Lixin Zheng Sihu Satoshi Miura 《中国地震研究》2001,15(3):252-265
INT正ODU**!0厂Nln以la Is located In the nol’th segmentdthe North－southselsnuc Belt,Whlchls thejuncturedthe Qinghai－Xizang(Dbet)block,Alxa block and Odos block．In that region,the tectonic activity。svery strong;。y strong earthquakes occu。d In history,such as the 1739 ingluo M。8．0 earthqu拙eandl920 Halyuan M。8．5 eafthquake,etc．; Merately strongeaFthquakes are still veryactlve atpresent,onlyln the Wuzhong－un斟m area,there have been7 e血hquakes tvlth M。＞5．0 to occ… 相似文献
8.
Stress drop estimates of moderate-magnitude earthquakes in the Umbria–Marche region, in the northern Apennines, exhibit a large scatter. For the two M w 5.7 and 6.0 main shocks of 26 September 1997 near Colfiorito, several papers resulted in stress drop estimates of 20 MPa, but values as low as 2–3 MPa were proposed as well. Also for the largest aftershocks (M w > 4), estimates spread from < 1 MPa up to values ten times larger. We have critically revisited methods and data used in the literature. We have specifically faced the trade-off between source and propagation effects, as we believe that it is responsible for a part of the large scatter. To keep this trade-off under control, we have applied a methodology that combines the best fit of both source spectra after Empirical Green’s Function (EGF) deconvolution and observed ground motion spectra, finding that the results of the two different data sets converge independently at the same solution. We have used ground motions observed in the Colfiorito basin, where an accelerograph and a co-located seismological broad-band station recorded three clusters of earthquakes in a broad magnitude interval (1.7 ≤ M w ≤ 6.0). We have found that the mainshock–aftershock sequences result in stress drops of 2–5 MPa at M w ≥ 5.6, with an average tendency to decrease at smaller magnitudes where stress drop variability increases. These findings confirm the source scaling recently assessed through Empirical Green’s Function deconvolution for another well-monitored seismic sequence of normal-faulting earthquakes, which struck the city of L’Aquila in the central Apennines in April 2009. The similar scaling law of the two areas suggests common mechanisms of stress release for the shallow normal faults in the Apennines. The propensity of smaller earthquakes to increase in variability, with a tendency toward smaller stress drops, may reflect an effect of fault strength heterogeneities for smaller size ruptures. 相似文献
9.
Using the 78 focal mechanism solutions of the fore shocks, main shock and after shocks of the earthquake sequence for the Yao'an earthquake, the characteristics of the focal faults and stress field for the earthquake sequence are analyzed. The results show that the main rupture plane of the Yao'an earthquake sequence is a tectonic fault with N50°W strike and steep dip and all the main shock, the fore shocks and the vast majority of after shocks occurred on the main rupture plane. A tectonic fracture with NNE-NE strike also participated in development process of the sequence. The focal stress field of the sequence dominated by principal compressional stress with nearly horizontal orientation SSE is consistent with the regional tectonic stress field. In the sequence development, the stress field in the focal region was complex with multi-azimuths and multi-action models and the focal rupture showed complex features with multi-directions and multi-patterns. 相似文献
10.
Qian Xiaodong 《中国地震研究》2007,21(1):43-54
Based on the data recorded by the regional digital seismic network of Yunnan and using new methods, the short-term variations of the ambient stress field of Yunnan and its adjacent areas are monitored in real time. With the in-depth analyses of the spatial-temporal evolution of the ambient stress field prior to the 2004, Shuangbai M_S5.0 earthquake, concrete procedures for predicting the three elements of the earthquake are presented. 相似文献
11.
Focal Mechanism of Small Earthquakes and Characteristics of Tectonic Stress Field in South China 总被引：3，自引：0，他引：3
《中国地震研究》1994,(2)
The focal mechanism of 200 small earthquakes in South China were determined by means of P and S amplitude ratios.The result indicates that P-axes of the recent tectonic stress field are characterized by a fan-shaped distribution.From the west to the east of the region,the P-axes concentrate on NNE-NW-NWW.T-axes of the recent tectonic stress field are characterized by an arc-shaped distribution.From Guangxi to Fujian Province along the coast,the T-axes concentrate on NWW-NEE-NNE.The average P-axes and T-axes are nearly horizontal. 相似文献
12.
The Canterbury earthquake sequence beginning with the 2010 M W 7.2 Darfield earthquake is one of the most notable and well-recorded crustal earthquake sequences in a low-strain-rate region worldwide and as such provides a unique opportunity to better understand earthquake source physics and ground motion generation in such a tectonic setting. Ground motions during this sequence ranged up to extreme values of 2.2 g, recorded during the February 2011 M W 6.2 event beneath the city of Christchurch. A better understanding of the seismic source signature of this sequence, in particular the stress release and its scaling with earthquake size, is crucial for future ground motion prediction and hazard assessment in Canterbury, but also of high interest for other low-to-moderate seismicity regions where high-quality records of large earthquakes are lacking. Here we present a source parameter study of more than 200 events of the Canterbury sequence, covering the magnitude range M W 3–7.2. Source spectra were derived using a generalized spectral inversion technique and found to be well characterized by the ω ?2 source model. We find that stress drops range between 1 and 20 MPa with a median value of 5 MPa, which is a factor of 5 larger than the median stress drop previously estimated with the same method for crustal earthquakes in much more seismically active Japan. Stress drop scaling with earthquake size is nearly self-similar, and we identify lateral variations throughout Canterbury, in particular high stress drops at the fault edges of the two major events, the M W 7.2 Darfield and M W 6.2 Christchurch earthquakes. 相似文献
13.
WuZhongliang 《中国地震研究》2002,16(1):20-26
Comparison between the NEIC broadband radiated energy catalogue and the Harvard CMT catalogue provides information about apparent stres.In spite of its significant uncertainties and limited relability, the clues obtained from this comparison seem interestiin in the physics of earthquakes.Scaling of apparent stress provides information about the dynamic friction along an earthquake fault.Relation between reduced energy and seismic moment implies that for strike-slip earthquakes,velocity-dependent friction plays a predominant role,while for non-strike-slip earthquakes,slip-dependent friction is predominant.It is also found that strike-slip events with extremely low apparent stress tend to occur“in single”,which is applied to the prediction of the seismic tendency following the 2001 Qinghai-Xizang(Tibet) borderMW7.8 earthquake. 相似文献
14.
On the basis of distribution of active fault and regional rheological structure, a three-dimensional finite element model of Sichuan-Yunnan region, China, is constructed to simulate contemporary crustal motion and stress distri- bution and discuss the dynamic mechanism of crustal motion and deformation in the Sichuan-Yunnan region. Lin- ear Maxwell visco-elastic model is applied, which includes the active fault zones, the elastic upper crust and vis- cous lower crust and upper mantle. Four different models with different boundary conditions and deep structure are calculated. Some conclusions are drawn through comparison. Firstly, the crustal rotation about the eastern syntaxis of the Himalaya in the Sicuan-Yunnan region may be controlled by the special dynamic boundary condition. The drag force of the lower-crust on the upper crust is not negligible. At the same time, the main active fault zones play an important role in the contemporary crustal motion and deformation in Sichuan-Yunnan region. 相似文献
15.
L. P. Imaeva B. M. Koz’min V. S . Imaev N. N. Grib S. V. Ashurkov 《Journal of Seismology》2017,21(2):385-410
The paper presents the modern structural-tectonic pattern and a tectonodynamic model of the zone of interaction of the most seismically active northeastern side of the Baikal rift zone (BRZ) and the conjugate system of seismogenic structures of the Aldan-Stanovoy block, where disastrous events with M ≥ 6.0 have been reported. Regularities in the structural formation of active faults and their kinematics are discussed. The faults form block structures accumulating significant tectonic strain. Motions between large tectonic blocks cause sudden release of the strain, which results in catastrophic events (M ≥ 6.0) with focal mechanisms of definite kinematic type. 相似文献
16.
By using 126 earthquake focal mechanism solutions (M S≥4.7) during the period of 1963～1998, modern tectonic stress field in North China is inverted by means of the step by step convergence. The inversion results indicate that the tectonic stress field in the research region is clearly variational in space and time: (1) The middling principal stress axis σ 2 is basically vertical. The maximum and minimum principal stress axes σ 1 and σ 2 are nearly horizontal, but the azimuths of σ 1 and σ 3 are inconsistent in different districts and periods. (2) Before the Tangshan earthquake in 1976, the three principal stress axes are uniform. The azimuth of maximum principal stress axis σ 1 is 68° (striking in a NEE-SWW direction). (3) After the Tangshan earthquake, the maximum principal stress axis σ 1 and minimum principal stress axis σ 3 have variations in different districts. In the northern area of North China and on the eastern side of the Tancheng-Lujiang fault zone, the maximum principal stress axis σ 1 is also striking in a NEE-SWW direction. Its azimuth is 68°. It is the same as that before the Tangshan earthquake. In the southern area of North China, the maximum principal stress axis σ 1 is striking in a E-W direction and its azimuth is 87°. 相似文献
17.
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18.
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19.
Bondur V. G. Gokhberg M. B. Garagash I. A. Alekseev D. A. 《Izvestiya Physics of the Solid Earth》2021,57(1):1-19
Izvestiya, Physics of the Solid Earth - Abstract—Since 2009, the stress-strain state (SSS) of the Earth’s crust in Southern California has been monitored using geomechanical modeling... 相似文献
20.
V. V. Adushkin A. A. Spivak V. A. Kharlamov 《Izvestiya Physics of the Solid Earth》2018,54(6):859-871
The results of processing and analyzing the instrumental observations of the Earth’s magnetic field at the Geophysical Observatory Mikhnevo of the Institute of Geosphere Dynamics of the Russian Academy of Sciences (IGD RAS) for 2010–2015 are presented. Quasi-harmonic components with the periods close to the lunar–solar tidal waves are revealed in the spectra of geomagnetic variations over a period of 0.4 to 30 days. The elliptical S1 tidal wave which is detected in the geomagnetic variations has modulations with periods of 1/3, 1/2, and 1 year. The spectra of the geomagnetic variations contain peaks corresponding to the free oscillations of the Earth. The analysis of the time series of the magnetic field for the period of the strong earthquakes in the absence of geomagnetic disturbances revealed the fine structure of the Earth’s fundamental spheroidal mode 0S2, which splits into five singlets. The established features of the spectrum of geomagnetic variations are helping the development of the new method for studying the deep structure of the Earth and the properties of the inner geospheres for estimating the viscosity of the Earth’s outer core and dynamics of the current systems in the outer (liquid) core, as well as for exploring, with the use of empirical data, the general regularities governing the regimes of energy exchange processes in the geospheres. 相似文献