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A. A. Avagimov V. A. Zeigarnik V. I. Okunev 《Izvestiya Physics of the Solid Earth》2011,47(10):919-925
The effects of elastic and electromagnetic (EM) fields are studied as an additional factor of energy exchange in the process
of the deformation of a heterogeneous medium. The threshold value of initiating energy, Ktr(kp), relative to the current relaxation process is quantitatively estimated. It is shown that the estimated energy impacts
below the threshold can initiate relaxation of local structural stresses and, thus, reduce the risk of a macrofracture. In
a seismically active region, a similar scenario of initiation of dynamic development is considered in the local zones of potential
sources of earthquakes. The possibility to determine the location, the time, and the intensity of the initiating EM impact
is considered. From the experiments, the coefficient of electromechanical conversion is calculated. 相似文献
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印尼MS8.7地震对中国大陆3次后续中强地震的动应力触发研究 总被引：2，自引：0，他引：2
印尼8.7级地震发生后,在不到2个月时间内,在中国大陆相继发生了3次后续中强地震(2004年12月26日云南双柏MS5.1地震、2005年1月26日云南思茅MS5.1地震、2005年2月15日新疆乌什MS6.2地震),印尼地震和这3次后续地震是否存在触发关系?计算了印尼地震在3次后续地震破裂面上的动库仑应力变化和静库仑应力变化。静应力变化量小,低于一般认为的触发阈值(0.01 MPa);动应力变化峰值为10-1MPa,可能是这3次后续地震的触发因素。 相似文献
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随着地震观测台站密度的不断增加以及地震检测技术的快速发展,微震研究受到了地震学界的广泛关注。与发震周期较长的大地震相比,微震复发周期短、发生频次高,可以获得更高分辨率的地壳内部介质物性和应力状态等变化信息。微震在许多领域具有广泛的应用,如研究断层几何形态、前震与地震成核的关系、余震时空演化特征及余震触发机理、远程动态触发现象、重复地震、诱发地震以及非火山震颤信号的检测等。高精度的微震定位结果可以揭示断裂带的精细几何形态和深部活动过程,促进对断层特性和地震物理过程的深入认识。本文简要总结了国内外微震研究的主要进展,包括微震检测的主要方法和微震在多个领域的研究实例,并对微震在地震科学中的应用前景进行了展望。 相似文献
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以南北地震带北部的青藏高原东北边缘与华北构造区过渡部位为例,通过建立地震构造模型,计算静态库仑破裂应力改变量（ΔCFS）,研究了该区1561~1920年360年间5次M≥7级地震之间的触发过程.结果表明,在1561年罗山东麓71/4级地震之后,下一次地震无一例外地发生在前面地震产生的应力触发区（ΔCFS>0）.在4条被触发的发震断裂中,有3条发震断裂的平均ΔCFS>0.2×105 Pa,最大可达0.62×105 Pa,超出目前普遍认为触发应力阀值（0.1×105 Pa）.根据断裂库仑破裂应力变化量（ΔCFS）和构造应力累计率（δτ）,计算获得了下一次地震发生的提前量（ΔT）,地震活动提前量最大可以达到160a.在一条重要活动构造带或地区上,一次地震发生对下一次地震的触发缩短了地震重复发生所需要的累积时间,使得地震可以提前发生,这一方面使得某一特定的发震断裂在时间尺度表现出准周期性,另一方面使得空间上不同发震断裂的地震活动表现出丛集发生的现象.此项研究有助于认识断裂间相互作用特点、揭示地震丛集发生规律以及预测未来地震危险区. 相似文献
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印尼8.7、 8.5级巨震对云南地区地震活动的远震触发分析 总被引：5，自引：0，他引：5
在收集整理印尼8.7、 8.5级巨震活动特点基础上, 分析了这两次巨震对云南地区地震活动的远震触发特征。 依据腾冲、 昆明两个台站的数字波形资料, 对这两次巨震的触发特点进行了分析。 认为云南地区2004年12月26日后地震活动的显著增强, 是由印尼8.7级巨震的长周期面波触发引起的。 8.5级地震后, 云南地区地震活动没有引起触发, 主要原因是8.7级地震已引起相关地震活动, 短期内断层不足以积累使其破裂的能量所致。 远震触发的地区与高热流地区一致。 相似文献
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长宁地区地震活动复杂,发生在长宁背斜轴部的长宁Ms6.0地震及其后续中强余震的震源机制与相距仅十几公里的南部向斜区内的中强震具有显著差异;这种差异仅仅是由于发震断层构造不同所造成的,还是孕育地震的应力场本身也存在局部变化?为了回答这一问题,本文在通过双差层析成像反演修正小震定位和波速结构的基础上,利用小震综合震源机制解方法获取了长宁地区地壳应力场的精细结构,并据此分析了其与中强震震源机制解的力学一致性.研究发现,长宁地区地壳应力场的最大主应力轴在整个区域内基本都处于近水平状态,其方位虽由北向南发生了一定角度的顺时针旋转,但也基本保持为近东西向;相比之下,应力类型在长宁背斜轴部和南部向斜区之间存在显著差异——前者为逆冲型,而后者为走滑型.同时,这两个局部区域的应力场与对应区域内的中强震震源机制解的吻合度较高,但与非对应区域内的中强震震源机制解的吻合度较低,甚至在力学上是相抵触的,表明区域应力场的局部改变是长宁地区复杂地震活动的必要力学基础.通过岩石力学估算,本文认为岩石泊松比的横向差异很可能是造成这种应力场局部改变的主要成因.此外,本文还对长宁Ms6.0地震序列的发震构造进行了探讨,认为长宁背斜轴部在6?9 km深度内存在基底断层,而正是这种基底断层在区域应力场作用下发生错动导致了长宁Ms6.0地震序列的发生. 相似文献
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从理论上讲,地震之间存在力学相关性,尤其是一个地震带内在临界状态,地震间相互作用增强。利用这种关系用地震触发响应系数扫描方法,可在一个强震发生后预测下次强震发生的地点。地震引起的就力场扰动包括静态、动态扰动,包括断层弹性位错,也有断层蠕动,可以有弹性地震波和粘弹性形变波的传播实现,有弹性变形,也有永久变形,有瞬间的,也有长久的效应等。这方面已提出好多种效应假说,多种效应共同作用的后果是一个。Ａｔ值 相似文献
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Immediately following the M S7.0 Lushan earthquake on April 20, 2013, using high-pass and low-pass filtering on the digital seismic stations in the Shanxi Province, located about 870–1,452 km from the earthquake epicenter, we detected some earthquakes at a time corresponding to the first arrival of surface waves in high-pass filtering waveform. The earthquakes were especially noticed at stations in Youyu (YUY), Shanzizao (SZZ), Shanghuangzhuang (SHZ), and Zhenchuan (ZCH), which are located in a volcanic region in the Shanxi Province,but they were not listed in the Shanxi seismic observation report. These earthquakes occurred 4–50 min after the passage of the maximum amplitude Rayleigh wave, and the periods of the surface waves were mainly between 15 and 20 s following. The Coulomb stresses caused by the Rayleigh waves that acted on the four stations was about 0.001 MPa, which is a little lower than the threshold value of dynamic triggering, therefore, we may conclude that the Datong volcanic region is more sensitive to the Coulomb stress change. To verify, if the similar phenomena are widespread, we used the same filtering to observe contrastively continuous waveform data before, and 5 h after, the M S7.0 Lushan earthquake and M S9.0 Tohoku earthquake in 2011. The results show that the similar phenomena occur before the earthquakes, but the seismicity rates after the earthquakes are remarkably increased. Since these weak earthquakes are quite small, it is hard to get clear phase arrival time from three or more stations to locate them. In addition, the travel time differences between P waves and S waves (S–P) are all less than 4 s, that means the events should occur in 34 km around the stations in the volcanic region. The stress of initial dynamic triggering of the M S9.0 Tohoku earthquake was about 0.09 MPa, which is much higher than the threshold value of dynamic triggering stress. The earthquakes after the M S9.0 Tohoku earthquake are related to dynamic triggering stress, but the events before the earthquake cannot be linked to seismic events, but may be related to the background seismicity or from other kinds of local sources, such as anthropogenic sources (i.e., explosions). Using two teleseismic filtering, the small background earthquakes in the Datong volcanic region occur frequently, thus we postulate that previous catalog does not apply bandpass filter to pick out the weak earthquakes, and some of the observed weak events were not triggered by changes in the dynamic stress field. 相似文献
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计算和研究了1976年云南龙陵Ms73、Ms74双主震产生的完全库仑破裂应力变化及其对后续震群序列的动态和静态应力触发作用.结果显示，龙陵第2主震受到了第1主震的动态和静态库仑破裂应力的触发作用.龙陵双主震的13个后续强余震中，发生在龙陵三角形块体内部的强余震，90%都受到了第1或第2主震的动态库仑破裂应力触发或静态库仑破裂应力触发作用，发生在三角形块体外部的强余震，2/3受到了第2主震的动态库仑破裂应力触发作用.从触发作用的强度和范围上看，第2主震的动态和静态库仑破裂应力触发作用都大于第1主震.就近场而言，受到龙陵双主震的动态和静态库仑破裂应力触发作用的余震数目相当，但动态库仑破裂应力的触发作用范围大于静态库仑破裂应力. 相似文献
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在许多地震触发研究案例中,不少学者都利用大地震造成的库仑应力变化研讨其对后续地震的影响,但众多结果中存在的共同规律尚未得到很好的统计与归纳。基于库仑应力变化理论,通过统计多个地震序列与典型事件中库仑应力研究结果,分别从震级,触发距离,触发地震库仑应力变化(ΔCFS)以及触发时间4个方面进行分析。结果表明,静态库仑应力的最优影响范围在5～50 km间,触发地震的应力条件多在0.01～0.4 MPa,触发地震震级与距离和主震震级无明显对应关系;动态触发的作用范围在100～2500 km间,主震震级通常较高,触发地震的震级都小于主震震级,在几个典型远程触发的事件分析中,主震震级与可触发距离呈正相关,但触发次数与其他所分析因素均无关;震后应力转移的三种机制,从理论上合理地解释了长时间尺度延迟触发的现象,但精确计算应力转移的量值可能对库仑应力变化与触发地震之间关系的更合理解释有推动作用,需引起关注。 相似文献
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通过吴忠—灵武地区现有的地震活动性资料,并结合该区域过去的几次中强震震例和已有的研究结果,本文梳理与总结了中强震前该区域地震活动乃至中国大陆大震活动的时空特征,而且基于最小完整性震级分析了1970—2019年该区域中小地震的地震活动性特点。综合认为,吴忠—灵武地区中强震的广义前震和中小地震的活动性具有较为鲜明的特征,中强震发生前1—2年内该区域及邻区形成ML2.0以上地震集中区或其西北方向的阿左旗腰坝区域大都出现ML3.0以上信号震,而且一年前其主震的广义前震的确比较发育,存在一定程度的地震增强;地震序列统计分析表明,该区域的多重共轭构造可能是其主要原因,其多震型、双震型和震群型占有相对较高的比例。另外,从大形势角度来看,过去大部分5级以上中强震发生的主导因素很可能由华北地块主导的强震活跃幕引起,该区域的强震危险性不仅仅和局部特殊构造特征、区域前震活动变化有关,更重要的是,华北—东北亚地块大震活动对其也起到了较大的影响作用,相比而言,青藏高原、龙门山断裂带及祁连山构造带等区域的大震活动对吴忠—灵武地区中强地震触发影响不显著,而且吴忠—灵武地区的中强地震活动和华北—东北亚地块的大震活动可能存在一定的构造响应。 相似文献
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以拉张正断层作用为主的京西盆岭活动构造区(112°～116.2°N, 38.3°～41.5°E)自BC231年以来共记载和记录15次M6～7.5地震。 本研究计算每一次强震产生的以及逐次积累的库仑破裂静应力变化, 并分析强震之间的应力触发关系。 结果显示在14次后发的强震中, 有10次发生在先发强震产生的积累库仑破裂静应力变化为正的触发区, 触发率为71%。 所有15次历史强震作用共同引起研究区积累库仑破裂静应力变化的正值区, 主要分布于六棱山北麓断裂中段、 怀涿盆地北缘断裂、 新保安沙城断裂、 桑干河断裂以及蔚县盆地南缘断裂, 并使得这些断裂(段)的强震危险性有所增加, 这可为分析研究区的未来强震危险性提供参考。 相似文献
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A SYSTEM OF CAPACITIVE HIGH-VOLTAGE PULSE RECHARGE/DISCHARGE AND ITS IMPLICATION ON EXPERIMENTALLY TRIGGERED EARTHQUAKE 
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下载免费PDF全文 An external small disturbance may trigger seismic events when the fault is in a critical state. The problems related with earthquakes triggered by the dynamic stress such as blasting loads, impact loads, volcanic eruptions and strong earthquakes, have usually drawn wide concerns in earthquake science, and the corresponding research contents are quite extensive, including earthquake triggering mechanisms, triggering earthquake uncertainty, aftershock triggering, and so on. Among them, experimental research is an important way to understand the stress triggering conditions and physical mechanisms, such as the influence of load disturbance on fault friction traits, the influence of periodic disturbance of tidal stress on fault instability, etc., all of which can be gained through experimental investigations. Among them, "how to trigger" is a basic scientific problem to increase the understanding of earthquake prediction theory, thus receiving more attention. There are also some studies that focus on "what happened after the trigger", that is, the sliding instability generated by the triggering method, and then the evolution characteristics of the sliding instability process. The well-known experimental study of the super-shear rupture process is conducted by using the electric explosion method to trigger the fault instability, and the high-speed camera records the super-shear rupture during the fault instability. This means that when the trigger source is controllable, it is possible to generate different types of instability processes, and then to explore which earthquakes will be triggered at different time and space positions under different stress states by means of active triggering. The study of stability analysis and instability process has important scientific significance.A stable system of capacitive high-voltage pulse discharge and recharge is one of basic techniques for studying the triggered earthquakes in laboratory. Based on the wire electric explosion method, this paper develops a controllable trigger experiment system. By designing a new capacitive high-voltage pulse charge and discharge system, while considering the actual needs of monitoring and system timing, multiple functions are integrated into one system. Functionally, in addition to realizing the dynamic loading and unloading function of the wire electric explosion method, the discharge process can be monitored, and the triggering, synchronization and timing signal output is performed with other observation systems, thus realizing the whole process monitoring of the dynamic disturbance action. After testing, the following functions are achieved:1)The voltage and current of the high-voltage charging power supply system can be automatically adjusted, and the system can be shut off after charging; 2)Control modes include manual and remote controls. These two modes can control the recharge, release and pulse discharge of the high voltage capacitor; 3)The system can produce multi-channel synchronous output, which satisfy multiple systems working together. In particular, the remote sensing method greatly improves the experimental maneuverability and security; 4)The system has multiple sets of gas discharge tube to trigger discharge, with a wide range of discharge voltage of 500~5 000V; 5)Roche coil resistance integral current detection can meet the transient resistance, large current detection. Test results indicate that this system has good repeatability and stability with the same discharge energy and discharge energy regulator, which is conducive to carry out single channel trigger of high-pressure discharge experiment. In short, the new charging and discharging system can meet the requirements of experimental study of triggering earthquake. In addition, this system can be used to generate the stress disturbance under certain static and dynamic conditions, and then judge whether this kind of mechanical conditions in active fault systems is currently stable.In short, a controllable single-shot discharge system is developed by a capacitive high-voltage pulse discharge system, which provides a good technical basis for experimental research on triggering earthquakes. In addition, the new system also has application significance:1)multiple triggering output can simultaneously start multiple systems and improve the efficiency of observation. Fault instability is a characteristic of transient response, so, its observation requires high-speed acquisition equipment, which is difficult to control on observation; the trigger system is controllable, with active synchronization observation using physical parameters; 2)stress disturbance can be triggered under static and dynamic loads to detect the safety and stability of the fault system with active trigger. 相似文献
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During the period of 1999~2002, the Chinese seismologists made a serious of developments in the study on seismic sources including observations, experiments and theory. In the field of observation, the methods of the accuracy location of earthquake sources, the inversion of seismic moment tensor and the mechanism of earthquake source are improved and developed. A lot of important earthquake events are studied by using these methods. The rupture processes of these events are inverted and investigated combined with the local stress fields and the tectonic moment by using the measurements of surface deformation. In the fields of experiments and theory, many developments are obtained in cause of seismic formation, condition of stress and tectonics, dynamics of earthquake rupture, rock fracture and nucleation of strong earthquakes. 相似文献
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中国西部北纬35°线附近地区7.0级以上强震分析 总被引：1，自引：0，他引：1
自1990年以来我国西部及邻近地区先后发生了6次7.0级以上地震,这些地震的震中位于35°N线附近,其纬度界于34.4°～36.2 °N之间,平均纬度为35.45 °N. 美国哈佛大学给出的震源机制表明,这些地震的主压应力轴方位一致性较好,都为NE向,似乎说明这些地震的发生是在统一的应力场作用下的结果,可能与印度板块对我国大陆的推挤作用有关. 结合地质构造和余震分布确定了发震断层,计算了它们产生的应力场,根据库仑破裂应力变化,分析了它们之间的相互影响. 结果显示,在这些地震中,对后续发生的地震可能具有促震作用. 根据引潮力在震源断层面上产生的有效剪切应力, 分析了引潮力对这些地震的触发效应, 结果没有显示这些地震的发生受到明显的引潮力触发. 相似文献
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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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On May 22, 2021, the MS 7.4 earthquake occurred in Madoi County, Qinghai Province; it was another strong event that occurred within the Bayan Har block after the Dari MS 7.7 earthquake in 1947. An earthquake is bound to cast stress to the surrounding faults, thus affecting the regional seismic hazard. To understand these issues, a three-dimensional viscoelastic finite element model of the eastern Bayan Har block and its adjacent areas was constructed. Based on the co-seismic rupture model of the Madoi earthquake, we analyzed the co- and post-seismic Coulomb stress change caused by the Madoi earthquake on the surrounding major faults. The results show that the Madoi earthquake caused significant co-seismic stress increases in the Tuosuo Lake and Maqin-Maqu segments of the East Kunlun fault (>10 ?kPa), which exceeded the proposed threshold of stress triggering. By integrating the accumulation rate of the inter-seismic tectonic stress, we conclude that the Madoi earthquake caused future strong earthquakes in the Tuosuo Lake and Maqin-Maqu segments of the East Kunlun fault to advance by 55.6-623 and 24.7-123 ?a, respectively. Combined with the influence of the Madoi earthquake and the elapsed time of the last strong earthquake, these two segments have approached or even exceeded the recurrence interval of the fault prescribed by previous research. In the future, it is necessary to focus greater attention on the seismic hazard of the Maqin-Maqu and Tuosuo Lake segments. This study provides a mechanical reference to understand the seismic hazard of the East Kunlun fault in the future, particularly to determine the seismic potential region. 相似文献