The long-term earthquake prediction from 2021 to 2030 is carried out by researching the active tectonic block boundary zones in the Chinese mainland.Based on the strong earthquake recurrence model,the cumulative proba...The long-term earthquake prediction from 2021 to 2030 is carried out by researching the active tectonic block boundary zones in the Chinese mainland.Based on the strong earthquake recurrence model,the cumulative probability of each target fault in the next 10 years is given by the recurrence period and elapsed time of each fault,which are adopted from relevant studies such as seismological geology,geodesy,and historical earthquake records.Based on the long-term predictions of large earthquakes throughout the world,this paper proposes a comprehensive judgment scheme based on the fault segments with the seismic gap,motion strongly locked,sparse small-moderate earthquakes,and apparent Coulomb stress increase.This paper presents a comprehensive analysis of the relative risk for strong earthquakes that may occur in the coming 10 years on the major faults in the active tectonic block boundary zones in the Chinese mainland.The present loading rate of each fault is first constrained by geodetic observations;the cumulative displacement of each fault is then estimated by the elapsed time since the most recent strong earthquake.展开更多
Vertical records are critically important when determining the rupture model of an earthquake, especially a thrust earthquake. Due to the relatively low fitness level of near-field vertical displacements, the precisio...Vertical records are critically important when determining the rupture model of an earthquake, especially a thrust earthquake. Due to the relatively low fitness level of near-field vertical displacements, the precision of previous rupture models is relatively low, and the seismic hazard evaluated thereafter should be further updated. In this study, we applied three-component displacement records from GPS stations in and around the source region of the 2013 MW6.6 Lushan earthquake to re-investigate the rupture model.To improve the resolution of the rupture model, records from both continuous and campaign GPS stations were gathered, and secular deformations of the GPS movements were removed from the records of the campaign stations to ensure their reliability. The rupture model was derived by the steepest descent method(SDM), which is based on a layered velocity structure. The peak slip value was about 0.75 m, with a seismic moment release of 9.89 × 10^(18) N·m, which was equivalent to an M_W6.6 event. The inferred fault geometry coincided well with the aftershock distribution of the Lushan earthquake. Unlike previous rupture models, a secondary slip asperity existed at a shallow depth and even touched the ground surface. Based on the distribution of the co-seismic ruptures of the Lushan and Wenchuan earthquakes, post-seismic relaxation of the Wenchuan earthquake, and tectonic loading process, we proposed that the seismic hazard is quite high and still needs special attention in the seismic gap between the two earthquakes.展开更多
The interseismic locking state of tectonic faults is essential for regional seismic hazard assessments.However,it is challenging to obtain this parameter reliably due to the weak deformation and complex model configur...The interseismic locking state of tectonic faults is essential for regional seismic hazard assessments.However,it is challenging to obtain this parameter reliably due to the weak deformation and complex model configurations.To better probe the fault locking state,more reliable physical models and well-covered observations are required.Here we investigate the locking state of the Xianshuihe fault based on a new-developed viscoelastic deformation model.Meanwhile,we combine GPS velocities from 13 new near-field stations and existing stations in this region to improve the spatial resolution.Similar to the theoretical predictions,our results indicate that the elastic model will clearly overestimate the fault locking depth and seismic moment accumulation rate,and the fault slip rate inferred from the elastic model is slightly lower than that from the viscoelastic model.Relying on the locking distribution inferred from the viscoelastic model,we identify four potential asperities on the Xianshuihe fault.More importantly,we find a clear spatial correlation between the fault locking distribution and the rupture extent of historical earthquakes,which indicates that the fault locking state may control the rupture extent and thus the magnitude of earthquakes.In addition,our results show that the 2022 M6.8 Luding earthquake only ruptured the south part of a potential asperity,and the accumulated energy in the northern unruptured area is equivalent to an Mw6.9 earthquake,where the seismic hazard deserves special attention.展开更多
Seismic and field observations indicate that the Mw7.4 Maduo earthquake ruptured the Jiangcuo fault,which is a secondary fault~85 km south of the northern boundary of the Bayan Hor block in western China.The kinematic...Seismic and field observations indicate that the Mw7.4 Maduo earthquake ruptured the Jiangcuo fault,which is a secondary fault~85 km south of the northern boundary of the Bayan Hor block in western China.The kinematic characteristics of the Jiangcuo fault can shed lights on the seismogenic mechanism of this earthquake.Slip rate is one of the key parameters to describe the kinematic features of a fault,which can also provide quantitative evidences for regional seismic hazard assessments.However,due to lack of effective observations,the slip rate of the Jiangcuo fault has not been studied quantitatively.In this study,we consider the interaction between the Jiangcuo fault and the eastern Kunlun fault,and estimate the slip rates of the two faults using the interseismic GPS observations across the seismogenic region.The inferred results show that the slip rates of the Jiangcuo fault and the Tuosuo Lake segment of the Kunlun fault are 1.2±0.8 and 5.4±0.3 mm a^(-1),respectively.Combining the slip rate with the average slip inferred from the coseismic slip model,the earthquake recurrence interval of the Jiangcuo fault is estimated to be 1800700+3700 years(1100–5500 years).Based on the results derived from previous studies,as well as calculations in this study,we infer that the slip rate of the Kunlun fault may decrease gradually from the Tuosuo Lake segment to the eastern tip.The Jiangcuo fault and its adjacent parallel secondary faults may have absorbed the relative motion of blocks together with the Kunlun fault.展开更多
基金the National Key R&D Program of China(grants 2017YFC1500501).
文摘The long-term earthquake prediction from 2021 to 2030 is carried out by researching the active tectonic block boundary zones in the Chinese mainland.Based on the strong earthquake recurrence model,the cumulative probability of each target fault in the next 10 years is given by the recurrence period and elapsed time of each fault,which are adopted from relevant studies such as seismological geology,geodesy,and historical earthquake records.Based on the long-term predictions of large earthquakes throughout the world,this paper proposes a comprehensive judgment scheme based on the fault segments with the seismic gap,motion strongly locked,sparse small-moderate earthquakes,and apparent Coulomb stress increase.This paper presents a comprehensive analysis of the relative risk for strong earthquakes that may occur in the coming 10 years on the major faults in the active tectonic block boundary zones in the Chinese mainland.The present loading rate of each fault is first constrained by geodetic observations;the cumulative displacement of each fault is then estimated by the elapsed time since the most recent strong earthquake.
基金supported by the grant from the National Sichuan-Yunnan earthquake prediction experimental field of CEA (grant No. 2016CESE0204)
文摘Vertical records are critically important when determining the rupture model of an earthquake, especially a thrust earthquake. Due to the relatively low fitness level of near-field vertical displacements, the precision of previous rupture models is relatively low, and the seismic hazard evaluated thereafter should be further updated. In this study, we applied three-component displacement records from GPS stations in and around the source region of the 2013 MW6.6 Lushan earthquake to re-investigate the rupture model.To improve the resolution of the rupture model, records from both continuous and campaign GPS stations were gathered, and secular deformations of the GPS movements were removed from the records of the campaign stations to ensure their reliability. The rupture model was derived by the steepest descent method(SDM), which is based on a layered velocity structure. The peak slip value was about 0.75 m, with a seismic moment release of 9.89 × 10^(18) N·m, which was equivalent to an M_W6.6 event. The inferred fault geometry coincided well with the aftershock distribution of the Lushan earthquake. Unlike previous rupture models, a secondary slip asperity existed at a shallow depth and even touched the ground surface. Based on the distribution of the co-seismic ruptures of the Lushan and Wenchuan earthquakes, post-seismic relaxation of the Wenchuan earthquake, and tectonic loading process, we proposed that the seismic hazard is quite high and still needs special attention in the seismic gap between the two earthquakes.
基金This study was supported by the National Key Research and Development Program of China(Grant No.2017YFC1500501)the National Natural Science Foundation of China(Grant No.41731072).
文摘The interseismic locking state of tectonic faults is essential for regional seismic hazard assessments.However,it is challenging to obtain this parameter reliably due to the weak deformation and complex model configurations.To better probe the fault locking state,more reliable physical models and well-covered observations are required.Here we investigate the locking state of the Xianshuihe fault based on a new-developed viscoelastic deformation model.Meanwhile,we combine GPS velocities from 13 new near-field stations and existing stations in this region to improve the spatial resolution.Similar to the theoretical predictions,our results indicate that the elastic model will clearly overestimate the fault locking depth and seismic moment accumulation rate,and the fault slip rate inferred from the elastic model is slightly lower than that from the viscoelastic model.Relying on the locking distribution inferred from the viscoelastic model,we identify four potential asperities on the Xianshuihe fault.More importantly,we find a clear spatial correlation between the fault locking distribution and the rupture extent of historical earthquakes,which indicates that the fault locking state may control the rupture extent and thus the magnitude of earthquakes.In addition,our results show that the 2022 M6.8 Luding earthquake only ruptured the south part of a potential asperity,and the accumulated energy in the northern unruptured area is equivalent to an Mw6.9 earthquake,where the seismic hazard deserves special attention.
基金supported by the National Key Research and Development Program of China(Grant Nos.2017YFC1500501 and 2017YFC1500305)the National Natural Science Foundation of China(Grant Nos.41674023 and 41304017).
文摘Seismic and field observations indicate that the Mw7.4 Maduo earthquake ruptured the Jiangcuo fault,which is a secondary fault~85 km south of the northern boundary of the Bayan Hor block in western China.The kinematic characteristics of the Jiangcuo fault can shed lights on the seismogenic mechanism of this earthquake.Slip rate is one of the key parameters to describe the kinematic features of a fault,which can also provide quantitative evidences for regional seismic hazard assessments.However,due to lack of effective observations,the slip rate of the Jiangcuo fault has not been studied quantitatively.In this study,we consider the interaction between the Jiangcuo fault and the eastern Kunlun fault,and estimate the slip rates of the two faults using the interseismic GPS observations across the seismogenic region.The inferred results show that the slip rates of the Jiangcuo fault and the Tuosuo Lake segment of the Kunlun fault are 1.2±0.8 and 5.4±0.3 mm a^(-1),respectively.Combining the slip rate with the average slip inferred from the coseismic slip model,the earthquake recurrence interval of the Jiangcuo fault is estimated to be 1800700+3700 years(1100–5500 years).Based on the results derived from previous studies,as well as calculations in this study,we infer that the slip rate of the Kunlun fault may decrease gradually from the Tuosuo Lake segment to the eastern tip.The Jiangcuo fault and its adjacent parallel secondary faults may have absorbed the relative motion of blocks together with the Kunlun fault.
