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Earthquake Research in China 2015年第1期29卷 84-102页

作者： Jia Ruo jiang haikun Institute of Earthquake Science China Earthquake Administration Beijing 100036 China China Earthquake Networks Center Beijing 100045 China

By the aftershock frequency estimation method based on the calculation of coseismic static Coulomb stress changes and rate-and state-dependent fault constitutive law,we calculate the frequency of "direct "aftershocks of the Wenchuan earthquake related to coseismic static Coulomb stress changes in its aftershock zone and the areas *** shows that the frequency is significantly lower than the truth in the main rupture zone,especially in the southern rupture zone,due to the decrease of stress level on the rupture plane of the main shock resulting from coseismic Coulomb stress *** study also shows that the effect of the Coulomb stress change on the duration of aftershock activity is associated with the lower limit *** duration is about 15-16 months for aftershocks above ML4.0,and close to 60 months for aftershocks above *** this period,the ratio of the"direct"aftershocks caused by coseismic Coulomb stress change ranges between 44.7% to48.6%,which suggests that,even in the "effective"period of coseismic Coulomb stress changes,about half of the aftershocks on the main shock rupture plane are independent of coseismic Coulomb stress *** is pointed out that those aftershocks may be related to the afterslip or the viscoelastic relaxation,which are time dependent cases.

关键词： Wenchuan earthquake Static Coulomb failure stress change "Direct"aftershock frequency Aftershock spatial distribution Afterslip

On Estimating Magnitude of a Maximum Sequent Earthquake by Viscoelastic Coulomb Stress Change and a Discussion of the Relationship between the M_S7.3 Earthquakes in Yutian 2008 and 2014

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Earthquake Research in China 2015年第4期29卷 434-451页

作者： Chen Yanan jiang haikun Lanzhou Institute of Seismology China Earthquake Administration Lanzhou 730000 China China Earthquake Networks Center Beijing 100045 China Earthquake Administration of Beijing Municipality Beijing 100080 China

On the basis of the previous studies of the layered crustal model in the Yutian area,combined with the field GPS continuous observation data,we roughly estimate the viscous coefficient of each layer. With the viscoelastic horizontal layer model,we calculate the viscoelastic co-seismic Coulomb stress change caused by the Yutian M_S7. 3 earthquakes 2008 and 2014 respectively. Based on the Coulomb stress change,using the calculation method of "direct "aftershock frequency,we come up with the theoretical earthquake frequency directly related to the mainshock and the co-seismic Coulomb stress change in the study area. Then we put forward a method,based on the comparison of theoretical and actual earthquake frequency or the comparison between theoretical and practical earthquake frequency-distance decay curve fitting residuals,to estimate the magnitude of a maximum sequent earthquake,directly related to the mainshock co-seismic Coulomb stress change. Results calculated by different methods show that the maximum follow-up earthquake magnitude caused by the coseismic Coulomb stress change lies from M_S7. 2 to M_S7. 5 following Yutian M_S7. 3 earthquake in 2008; but that of the 2014 Yutian M_S7. 3 earthquake is M_S6. 3. The former is very close to the Yutian M_S7. 3 earthquake in *** of the same magnitude,relatively close spatial distance,short time interval,the same region of the external force,the strong correlation between two seismic tectonic and a clear stress interaction,we thus consider that the two Yutian M_S7. 3 earthquakes in 2008 and 2014 constitute a pair of generalized double shock type earthquake. This is consistent with the sequence type characteristic of past "double shock"earthquakes in the region. In this paper,the influence of the magnitude lower limit and the b-value in the relationship of G-R on the results is discussed. As a result,when the viscoelastic coseismic Coulomb stress variation is determined,the lower limit of magnitude has little eff

关键词： The Yutian MS7.3 earthquake in 2008 The Yutian MS7.3 earthquake in 2014 Viscoelastic medium horizontal layered model Viscosity coefficient Viscoelasticity coseismic Coulomb stress changes Maximum sequent earthquake magnitude

A Review on Research of Foreshocks

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Earthquake Research in China 2016年第4期30卷 470-484页

作者： Zhou Shaohui jiang haikun Institute of Earthquake Science CEABeijing 100036China vChina Earthquake Networks Center Beijing 100045China

This paper briefly introduces the current research progress in the field of foreshocks,both in China and abroad,and contrasts the common characteristics and the mechanisms of foreshocks of the sequence under the definition of different conditions of foreshocks. The main recognition methods of foreshocks are briefly reviewed,and their characteristics and existing problems are reviewed and discussed. Foreshocks are small earthquakes that occur before the mainshock and adjacent to the main source location. A foreshock sequence is constituted of a series of foreshock activities that occur before the mainshock. The proportion of earthquake cases includes direct foreshocks ranging from 10% - 40% at different defined conditions of foreshocks. Theoretically,cascade model or pre-slid model can explain foreshocks. Foreshocks are mainly concentrated in the range of 10km -75 km of the mainshock,but their time distribution form is very complicated,mostly prior to the mainshock from 1 or 2 days,the seismicity rate of part of foreshock sequences shows significant acceleration features,but many foreshock sequences often show the attenuation characteristics of mainshock-aftershock sequences. The most prominent feature of foreshocks is a focal consistent mechanism and low b-value of earthquakes of the earthquake sequence. Foreshocks seems to have a certain relationship with tectonic environment and the rupture form of the mainshock,in limited foreshocks earthquake cases,the dip-thrusting earthquakes seem to have relatively more foreshocks. The results of some of the earthquake cases show that the focal depth of foreshocks gradually moved downward with the mainshock approaching. So far,it is difficult to determine whether an earthquake or an earthquake sequence is a foreshock or foreshock sequence before the mainshock. The identification methods of foreshocks mainly include a statistical method of analogy,focal consistent mechanism and related derivative method,the fine detection of t

关键词： Foreshocks Foreshock definition Foreshock identification Mechanism of foreshocks

Comparative Study of Changes in Stress-drop of the Jinggu MS6.6 and Ludian MS6.5 Earthquake Sequences

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Earthquake Research in China 2017年第2期31卷 151-168页

作者： Zhou Shaohui jiang haikun Qu Junhao Earthquake Administration of Shandong Province Jinan 250102 China China Earthquake Networks Center Beijing 100045 China

The earthquake stress-drop values of two sequences were accurately calculated after taking away the effects due to regional earthquake anelastic attenuation and station site response,using waveform data and seismic phase data of sequences of the Jinggu M_S6. 6,and Ludian M_S6. 5 earthquakes in Yunnan. These results show that the stress drop with magnitude increases within the scope of this study of magnitude. After eliminating the influence of the magnitude,the average value of stress-drop in the Jinggu sequence is higher than that of the Ludian sequence at the same magnitude range. This may be related to the stress state in different regions. In terms of the changes of time and space of stress-drop,before M_S5. 8 strong aftershock,the stress-drop is "slowing down-turning up-keeping a high value"after the mainshock,meanwhile,almost all of the abnormally high stress drop value is distributed around the M_S5. 8 strong aftershock, showing that the stress environment in the region was increasing after the mainshock. And after the M_S5. 9 strong aftershock,stress-drop rapidly declines to a relatively stable state,meanwhile,the high value of stress-drop is distributed around the strong aftershock,showing that the regional tectonic stress gets more fully release,its stress environment begins to rapidly *** the Ludian sequence without a strong aftershock occurring,the average value of stress drop is lower than that of the Jinggu earthquake sequence at the same magnitude range,while at the same time,the stress-drop of the aftershock sequence almost hasn't changed much. In the time after the mainshock,combined with the release characteristics of the main energy,the stress in the region is excessively released,the subsequent stress in the region gradually returns to normal. This may be the reason why the activity of Ludianaftershocks significantly was weaker and subsequently there were no strong aftershocks occurred.

关键词： Stress-drop Aftershock sequence Ludian earthquake Jinggu earthquake

Earthquake Probability of the“Seismic Gap”on the Longmenshan Fault

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Earthquake Research in China 2018年第1期32卷 15-27页

作者： Song Jin jiang haikun Meng Lingyuan Zang Yang China Earthquake Networks Center Beijing 100045China Institute of Geophysics China Earthquake AdministrationBeijing 100081China

Using the layered viscoelastic medium model,this paper calculated the coulomb stress loading effect on the Lushan epicenter generated by the Wenchuan *** combined with the rate-state friction law proposed by Dieterich J.(1994),we obtain the probability of an0 earthquake occurring in the vicinity of *** results show that the probability of0 earthquake of the Lushan region in 2013 is up to18%,indicating that the stress disturbance caused by the Wenchuan earthquake accelerated the Lushan *** paper also calculates the coulomb stress accumulation on the"seismic gap"generated by the two earthquakes of Wenchuan and Lushan,and combined with the background seismicity,gives the6.0 earthquake probability of the"seismic gap".Although there may be a certain error in the results because of the Dayi earthquake,selection of the medium model parameters and background seismicity,the seismic probability of the"seismic gap"is ***,we think destructive earthquakes are still likely to occur in the"seismic gap".

关键词： The coulomb stress The rate-state friction law Earthquake probability

A Statistical Analysis on Recent Tidal Triggering of the Earthquake in the Tianshan Seismic Zone

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Earthquake Research in China 2015年第2期29卷 203-213页

作者： Li Jin jiang haikun Qu Junhao Huang Yu Gao Chaojun Earthquake Administration of Xinjiang Uygur Autonomous Region China Earthquake Networks Center Earthquake Administration of Shandong Province Kashi Standard Seismic Station Earthquake Administration of Xinjiang Uygur Autonomous Region

A statistical analysis is done to study the spatio-temporai features of earthquake activity in the Tianshan seismic belt triggered by tide, based on Schuster＇s test. The data we choose is the ML ≥2. 0 earthquakes from January 1, 2010 to August 31, 2012 in eastern Tianshan, and the calculation is on tidal body stress. The results show that the p-value based on the time window smoothing of Schuster＇s test corresponds better with the strong earthquakes in the Tianshan seismic belt, especially for a long time before the November 1, 2011 Nilka Ms6. 0 earthquake, when the p-value of the Schuster＇s test was always lower than the threshold of 0. 05 for tidal trigger of earthquake, but after the Niika Ms6. 0 earthquake, that value was quickly restored to a high level, which reflects a close relationship between the Nilka Ms6. 0 earthquake and the Earth tide. According to the p-value based on the spatial window smoothing of Schuster＇s test, the Nilka Ms6. 0 earthquake was at or near the tidal triggering area. Thus we can see from the spatio-temporal results that the Nilka Ms6. 0 earthquake was obviously triggered by Earth fide.

关键词： Tianshan seismic zone Nilka earthquake Tidal triggering Schuster's test

A Statistical Analysis on the Wenchuan Aftershock Activity Triggered by Earth Tide

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Earthquake Research in China 2013年第1期27卷 23-38页

作者： Li Jin jiang haikun Earthguake Administration of Xinjiang Uygur Autonomous Region China Earthquake Networks Center

A statistical analysis on the Wenchuan aftershock activity triggered by tidal forces is systematically studied based on Schusters test, including earthquakes triggered by tidal force, tidal stress and tidal coulomb failure stress. The results show that a group of strong aftershocks which occurred at the end of July to early August in 2008 at the north of Wenchuan were obviously triggered by earth tide, the same conclusion is drawn by Schusters smooth test of the tidal force, tidal stress and tidal coulomb failure stress. In addition, the Wenchuan aftershock activity is obviously triggered by fortnight tide. In the north, the aftershocks happened more frequently in the first and last quarters of the moon, and in the south, the aftershocks happened more frequently in the first and last quarters of the moon and during the full moon.

关键词： Wenchuan aftershocks Tidal triggering Schuster's test

The Effect of Static Stress Triggering of the M_S 7. 1 Yushu Earthquake

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Earthquake Research in China 2012年第3期26卷 348-354页

作者： Song Jin jiang haikun China Earthquake Networks Center Beijing 100045 China

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.

关键词： Ms7. 1 Yushu earthquake Coulomb stress changes Aftershock distribution Regional stress

A Review on Tidal Triggering of Earthquakes

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Earthquake Research in China 2012年第1期26卷 128-141页

作者： Li Jin jiang haikun Institute of Earthquake Science CEA Beijing 100036 China China Earthquake Networks Center Beijing 100045 China

Research of tidal triggering of earthquakes in recent years is systematically reviewed,focusing on the relationship between the phases of the moon and seismic activity,earthquakes triggered by tidal forces and its components,based on the large sample statistics to discuss the tidal triggering of an *** relationship between the phase of the moon and seismic activity is a preliminary study of tidal triggering of earthquakes,and the modulation ratio is a quantitative description of *** the resolution of tidal stress to study seismic activity is a way to reveal the relationship between the tides and earthquakes from the mechanics point of *** sample statistics is another way to study the relationship between the tidal and earthquake from the view of *** many statistical methods,Schuster's test is used more widely,which takes many factors into account,such as focal mechanism,tidal stress,and statistical tests to quantitatively analyze the tidal triggering effect on earthquakes.

关键词： Seismic activity Triggering Tidal force Schuster's test

Discussion on Earthquake Forecasting and Early Warning

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Earthquake Research in China 2008年第4期22卷 416-427页

作者： Zhang Xiaodong jiang haikun Li Mingxiao China Earthquake Networks Center Beijing 100045 China

Through analysis of natural and social attributes of earthquake forecasting,the relationship between the natural and social attributes of earthquake forecasting(early warning)has been *** the natural attributes of earthquake forecasting,it only attempts to forecast the magnitude,location and occurrence time of future earthquake based on the analysis of observational data and relevant theories and taking into consideration the present understanding of seismogeny and earthquake *** need not consider the consequences an earthquake forecast involves,and its purpose is to check out the level of scientific understanding of *** respect of the social aspect of earthquake forecasting,people also focus on the consequence that the forecasting involves,in addition to its natural aspect,such as the uncertainty of earthquake prediction itself,the impact of earthquake prediction,and the earthquake resistant capability of structures(buildings),lifeline works,*** a word,it highlights the risk of earthquake forecasting and tries to mitigate the earthquake hazard as much as *** this paper,the authors also discuss the scientific and social challenges faced in earthquake prediction and analyze preliminarily the meanings and content of earthquake early warning.

关键词： Earthquake early warning Earthquake forecasting Social attribute Natural attribute