地震引起邻近断层的静应力变化可能推迟、加速、甚至触发以后的地震(Das and Scholz, 1981; Stein and Lisowski, 1983; Hudnut et al., 1989; Reasenberg et al., 1992; Du and Aydin, 1993; Harris et al., 1992; Joumé et al., ...地震引起邻近断层的静应力变化可能推迟、加速、甚至触发以后的地震(Das and Scholz, 1981; Stein and Lisowski, 1983; Hudnut et al., 1989; Reasenberg et al., 1992; Du and Aydin, 1993; Harris et al., 1992; Joumé et al., 1992; Stein et al., 1992; Simpson et al., 1994; Harris and Simpson, 1993)。这种作用的持续时间长度对地震灾害估计中应力分析的可能作用具有很大影响,但现在还不知道。这里我们采用弹性半空间模型(Okada,1992)来估计过去26a来南加州破坏性地震(M≥5)所产生的静应力变化,并且观察这些变化对以后的地震活动的影响。我们发现在M≥5地震之后的1.5a内,任何一个后来附近的M≥5地震几乎总是使受第一次地震加载而趋于破坏的断层破裂。在这个时期以后,破坏性地震使加载和卸载的断层破裂的可能性几乎是相同的。我们的结果显示,在南加州破坏性地震之后的短时期内,简单的库伦应力破坏模型可以用来识别地震危险性增大的地区。展开更多
Non-consistency of stress results is of ten observed during field measurements. In some cases, even the rneasurernents are made at the same location in a massive rockrnass, the results can vary widely. In order to sol...Non-consistency of stress results is of ten observed during field measurements. In some cases, even the rneasurernents are made at the same location in a massive rockrnass, the results can vary widely. In order to solve the problem, extensive research has been carried out to study the major factors wh1ch rnay affect stress deterrnlnation. They include the rock behaviour and the stress state. For rocks showing non-isotropic behaviour, the values of Young’s modulus and Poisson ratio vary with the orientation of loading and measurement. Stress condition in the rock affects the rock behaviour. Furtherrnore, the loading condition on rock samples durlng laboratory tests is different from in the field and therefore the determined e1astic constants may not represent the field condi tion. In general , the Young’s modulus may depend on the orientation, the loading path, the stress magnitude and the stress ratio. This paper examines in detail the effects of those factors, especially for rocks showing transversely isotropic behaviour. It is found that the discrepancy of stress results from field measurernents in this type of rock is mainly due to over simplification of the rock behavior and inadequate use of elastic constants of the rock during stress calculation. A case study is given,which indicates the significance of these factors and demonstrates the proper procedure for stress calculation from measurements.展开更多
This paper calculates the static Coulomb stress changes generated by four earthquakes in the Yutian area during 2008 ~ 2014 separately,then discusses the triggering influence,their accumulated Coulomb stress changes a...This paper calculates the static Coulomb stress changes generated by four earthquakes in the Yutian area during 2008 ~ 2014 separately,then discusses the triggering influence,their accumulated Coulomb stress changes and their influence on nearby faults.The results indicate that the M S5.5 earthquake in 2011 and the M_S7.3 earthquake in 2014 are both in the regions where the Coulomb stress change is positive,the stress changes are 0.004 MPa and 0.021 MPa, respectively, meaning they are triggered by prior earthquakes.The M S6.2 earthquake in 2012 occurred in the place where Coulomb stress change was negative,so it is postponed by the prior earthquakes.The image of Coulomb stress changes of the M S7.3 earthquake in 2014 is in accord with aftershocks( M L≥ 3.0)distribution,but some regions on the fault where the Coulomb stress change is positive have few aftershocks,and strong aftershocks may occur at these districts in future.In addition,this paper calculates the Coulomb stress change on nearby faults,and finds that the Coulomb stress changes of different elements in the GGC fault are very different,and must receive strong triggered-influence,though the result may be influenced by the input finite fault model,so there is still a large earthquake-risk.The GGN,PLC,PLW and LBW faults were also triggered by the four earthquakes occurring between 2008 ~ 2014.Their maximum Coulomb stress changes all exceed 0.002 MPa,so they also have a strong earthquake hazard.展开更多
Static Coulomb stress change induced by earthquake slip is frequently used to explain earthquake activities and aftershock distribution.However,some parameters for the Coulomb stress calculation are unable to be well ...Static Coulomb stress change induced by earthquake slip is frequently used to explain earthquake activities and aftershock distribution.However,some parameters for the Coulomb stress calculation are unable to be well constrained from laboratory experiments and field observations.Different parameters may directly affect the pattern of static Coulomb stress.The static Coulomb stress changes induced by the Wenchuan earthquake calculated by six research groups are not consistent with each other.To investigate how the parameters affect the calculation results,we change the parameters in turn through modeling and compare the results of different calculation parameters.We find that gravity,position and strike of receiver faults have little influence on coseismic Coulomb stress calculations,but other parameters can change the value and sign of the results in various degrees especially around the earthquake rupture plane.Therefore the uncertainty analysis of static Coulomb stress change induced by earthquake should be taken into consideration in the earthquake hazard analysis.展开更多
This paper calculates the static stress changes generated by the Yushu M_S 7. 1 earthquake in Qinghai Province. On the basis of regional stress,we take account of the static stress change triggered by the Yushu M_S 7....This paper calculates the static stress changes generated by the Yushu M_S 7. 1 earthquake in Qinghai Province. On the basis of regional stress,we take account of the static stress change triggered by the Yushu M_S 7. 1 earthquake to find the optimally oriented fault planes,then calculate the Coulomb stress change on the optimally oriented fault plane. The results indicate that most of the aftershocks are triggered by the mainshock. The image of Coulomb stress changes is also in accord with regional earthquakes ( M_L ≥3. 0 ) distribution,but the value is lower than 0. 01MPa. In addition,this paper calculates the Coulomb stress changes in the case that the aftershock fault plane is the same as the main shock. Through comparison,we find that the image of Coulomb stress changes obtained using the "optimally oriented fault"approach is more consistent with the distribution of Yushu aftershocks and regional earthquakes.展开更多
文摘地震引起邻近断层的静应力变化可能推迟、加速、甚至触发以后的地震(Das and Scholz, 1981; Stein and Lisowski, 1983; Hudnut et al., 1989; Reasenberg et al., 1992; Du and Aydin, 1993; Harris et al., 1992; Joumé et al., 1992; Stein et al., 1992; Simpson et al., 1994; Harris and Simpson, 1993)。这种作用的持续时间长度对地震灾害估计中应力分析的可能作用具有很大影响,但现在还不知道。这里我们采用弹性半空间模型(Okada,1992)来估计过去26a来南加州破坏性地震(M≥5)所产生的静应力变化,并且观察这些变化对以后的地震活动的影响。我们发现在M≥5地震之后的1.5a内,任何一个后来附近的M≥5地震几乎总是使受第一次地震加载而趋于破坏的断层破裂。在这个时期以后,破坏性地震使加载和卸载的断层破裂的可能性几乎是相同的。我们的结果显示,在南加州破坏性地震之后的短时期内,简单的库伦应力破坏模型可以用来识别地震危险性增大的地区。
文摘Non-consistency of stress results is of ten observed during field measurements. In some cases, even the rneasurernents are made at the same location in a massive rockrnass, the results can vary widely. In order to solve the problem, extensive research has been carried out to study the major factors wh1ch rnay affect stress deterrnlnation. They include the rock behaviour and the stress state. For rocks showing non-isotropic behaviour, the values of Young’s modulus and Poisson ratio vary with the orientation of loading and measurement. Stress condition in the rock affects the rock behaviour. Furtherrnore, the loading condition on rock samples durlng laboratory tests is different from in the field and therefore the determined e1astic constants may not represent the field condi tion. In general , the Young’s modulus may depend on the orientation, the loading path, the stress magnitude and the stress ratio. This paper examines in detail the effects of those factors, especially for rocks showing transversely isotropic behaviour. It is found that the discrepancy of stress results from field measurernents in this type of rock is mainly due to over simplification of the rock behavior and inadequate use of elastic constants of the rock during stress calculation. A case study is given,which indicates the significance of these factors and demonstrates the proper procedure for stress calculation from measurements.
基金funded by the National Key Technology R&D Program of China(2012BAK19B02)
文摘This paper calculates the static Coulomb stress changes generated by four earthquakes in the Yutian area during 2008 ~ 2014 separately,then discusses the triggering influence,their accumulated Coulomb stress changes and their influence on nearby faults.The results indicate that the M S5.5 earthquake in 2011 and the M_S7.3 earthquake in 2014 are both in the regions where the Coulomb stress change is positive,the stress changes are 0.004 MPa and 0.021 MPa, respectively, meaning they are triggered by prior earthquakes.The M S6.2 earthquake in 2012 occurred in the place where Coulomb stress change was negative,so it is postponed by the prior earthquakes.The image of Coulomb stress changes of the M S7.3 earthquake in 2014 is in accord with aftershocks( M L≥ 3.0)distribution,but some regions on the fault where the Coulomb stress change is positive have few aftershocks,and strong aftershocks may occur at these districts in future.In addition,this paper calculates the Coulomb stress change on nearby faults,and finds that the Coulomb stress changes of different elements in the GGC fault are very different,and must receive strong triggered-influence,though the result may be influenced by the input finite fault model,so there is still a large earthquake-risk.The GGN,PLC,PLW and LBW faults were also triggered by the four earthquakes occurring between 2008 ~ 2014.Their maximum Coulomb stress changes all exceed 0.002 MPa,so they also have a strong earthquake hazard.
基金sponsored by the Special Scientific Research Projects on Earthquake of Institute of Earthquake Science,CEA (IES0207690213)China Earthquake Administration(CEA200708008)
文摘Static Coulomb stress change induced by earthquake slip is frequently used to explain earthquake activities and aftershock distribution.However,some parameters for the Coulomb stress calculation are unable to be well constrained from laboratory experiments and field observations.Different parameters may directly affect the pattern of static Coulomb stress.The static Coulomb stress changes induced by the Wenchuan earthquake calculated by six research groups are not consistent with each other.To investigate how the parameters affect the calculation results,we change the parameters in turn through modeling and compare the results of different calculation parameters.We find that gravity,position and strike of receiver faults have little influence on coseismic Coulomb stress calculations,but other parameters can change the value and sign of the results in various degrees especially around the earthquake rupture plane.Therefore the uncertainty analysis of static Coulomb stress change induced by earthquake should be taken into consideration in the earthquake hazard analysis.
基金sponsored by the National Key Technology R&D Program,China (2008BAC38B03-01)
文摘This paper calculates the static stress changes generated by the Yushu M_S 7. 1 earthquake in Qinghai Province. On the basis of regional stress,we take account of the static stress change triggered by the Yushu M_S 7. 1 earthquake to find the optimally oriented fault planes,then calculate the Coulomb stress change on the optimally oriented fault plane. The results indicate that most of the aftershocks are triggered by the mainshock. The image of Coulomb stress changes is also in accord with regional earthquakes ( M_L ≥3. 0 ) distribution,but the value is lower than 0. 01MPa. In addition,this paper calculates the Coulomb stress changes in the case that the aftershock fault plane is the same as the main shock. Through comparison,we find that the image of Coulomb stress changes obtained using the "optimally oriented fault"approach is more consistent with the distribution of Yushu aftershocks and regional earthquakes.
