The M_(S)6.9 Menyuan earthquake in Qinghai Province,west China is the largest earthquake by far in 2022.The earthquake occurs in a tectonically active region,with a background b-value of 0.87 within 100 km of the epic...The M_(S)6.9 Menyuan earthquake in Qinghai Province,west China is the largest earthquake by far in 2022.The earthquake occurs in a tectonically active region,with a background b-value of 0.87 within 100 km of the epicenter that we derived from the unified catalog produced by China Earthquake Networks Center since late 2008.Field surveys have revealed surface ruptures extending 22 km along strike,with a maximum ground displacement of 2.1 m.We construct a finite fault model with constraints from In SAR observations,which showed multiple fault segments during the Menyuan earthquake.The major slip asperity is confined within 10 km at depth,with the maximum slip of 3.5 m.Near real-time back-projection results of coseismic radiation indicate a northwest propagating rupture that lasted for~10 s.Intensity estimates from the back-projection results show up to a Mercalli scale of IX near the ruptured area,consistent with instrumental measurements and the observations from the field surveys.Aftershock locations(up to January 21,2022)exhibit two segments,extending to~20 km in depth.The largest one reaches M_(S)5.3,locating near the eastern end of the aftershock zone.Although the location and the approximate magnitude of the mainshock had been indicated by previous studies based on paleoearthquake records and seismic gap,as well as estimated stressing rate on faults,significant surfacebreaching rupture leads to severe damage of the high-speed railway system,which poses a challenge in accurately assessing earthquake hazards and risks,and thus demands further investigations of the rupture behaviors for crustal earthquakes.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 × 1018 N·m, which was equivalent to an MW6.6 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 2019 M_(S)6.0 Changning earthquake occurred in the tectonically stable Sichuan Basin,where the epicenter and its adjacent areas are important shale gas and salt mine production fields,resulting in hot debates on w...The 2019 M_(S)6.0 Changning earthquake occurred in the tectonically stable Sichuan Basin,where the epicenter and its adjacent areas are important shale gas and salt mine production fields,resulting in hot debates on whether the seismogenic mechanism of the 2019 Changning earthquake is related to human activities.As source characteristics and fluid pressure can provide important constraints on whether an earthquake is induced,weinvestigate the seismogenic mechanisms of the mainshock and 9 MW≥4.0 aftershocks.In overall,the mainshock and the majority of the aftershocks are characterized by relatively shallow focal depths(1‒4 km)and significant non-double-couple(non-DC)components.However,the mainshock and the aftershocks differ in two aspects:(1)the compensated-linear-vector-dipole components dominate the non-DC components of the mainshock,whereas the isotropic components dominate the most aftershocks;(2)the fluid overpressure of the mainshock is over 30 MPa,whereas the fluid overpressure of the most aftershocks is less than 10 MPa.Thus,we propose that the mainshock is triggered by weakened fault strength with long-term fluid injection,and that its large non-DC components are associated withcomplex rupture processes.Comparatively,the aftershocks may be triggered by postseismic stress transfer by combining the Coulomb failure stress changes in the poroelastic medium.Our results highlight the possible role of fluid in the occurrence of the Changning earthquake sequence.展开更多
On December 18,2023,the MS 6.2 Jishishan earthquake occurred in the northeastern region of the Qinghai-Xizang Plateau,causing heavy casualties and property damage in Gansu and Qinghai Provinces.In this study,we integr...On December 18,2023,the MS 6.2 Jishishan earthquake occurred in the northeastern region of the Qinghai-Xizang Plateau,causing heavy casualties and property damage in Gansu and Qinghai Provinces.In this study,we integrate space imaging geodesy,finite fault inversion,and back-projection methods to decipher its rupture property,including fault geometry,coseismic slip distribution,rupture direction,and propagation speed.The results reveal that the seismogenic fault dips to the southwest at an angle of 29.The major slip asperity is dominated by reverse slip and is concentrated within a depth range of 7-16 km,which explains the significant uplift near the epicenter observed by both the Sentinel-1 ascending and descending InSAR data.Moreover,the teleseismic array waveforms indicate a northwest propagating rupture with an overall slow rupture velocity of~1.91 km/s(AK array)or 1.01 km/s(AU array).展开更多
1.Background on the seismic gap between the Wenchuan and the Lushan earthquakes The 2008 Mw7.9 Wenchuan earthquake and the 2013 Mw6.9 Lushan earthquake,which occurred in the Longmenshan fault system(hereafter called L...1.Background on the seismic gap between the Wenchuan and the Lushan earthquakes The 2008 Mw7.9 Wenchuan earthquake and the 2013 Mw6.9 Lushan earthquake,which occurred in the Longmenshan fault system(hereafter called LMSFS),caused dramatically casualties and huge economic losses.Their aftershock zones outline a seismic gap of about 50 km(Figure 1).展开更多
基金supported by China Earthquake Sciences Experiment Site(2018CSES0102)China Earthquake Administration Science for Earthquake Resilience(XH20072)+2 种基金National Key R&D Program of China(No.2018YFC0603500)atural Science Foundation of China(41874062 and 41922025)Youth Science and Technology Fund Project of CENC。
文摘The M_(S)6.9 Menyuan earthquake in Qinghai Province,west China is the largest earthquake by far in 2022.The earthquake occurs in a tectonically active region,with a background b-value of 0.87 within 100 km of the epicenter that we derived from the unified catalog produced by China Earthquake Networks Center since late 2008.Field surveys have revealed surface ruptures extending 22 km along strike,with a maximum ground displacement of 2.1 m.We construct a finite fault model with constraints from In SAR observations,which showed multiple fault segments during the Menyuan earthquake.The major slip asperity is confined within 10 km at depth,with the maximum slip of 3.5 m.Near real-time back-projection results of coseismic radiation indicate a northwest propagating rupture that lasted for~10 s.Intensity estimates from the back-projection results show up to a Mercalli scale of IX near the ruptured area,consistent with instrumental measurements and the observations from the field surveys.Aftershock locations(up to January 21,2022)exhibit two segments,extending to~20 km in depth.The largest one reaches M_(S)5.3,locating near the eastern end of the aftershock zone.Although the location and the approximate magnitude of the mainshock had been indicated by previous studies based on paleoearthquake records and seismic gap,as well as estimated stressing rate on faults,significant surfacebreaching rupture leads to severe damage of the high-speed railway system,which poses a challenge in accurately assessing earthquake hazards and risks,and thus demands further investigations of the rupture behaviors for crustal earthquakes.
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 × 1018 N·m, which was equivalent to an MW6.6 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supported by the high-performance computing platform TS10000 of the School of Geophysics and Geomatics,China University of Geosciences(Wuhan)supported by the National Natural Science Foundation of China(Grant Nos.42274082,42030108,41874053)Fundamental Research Funds for the Central Universities,China University of Geosciences(Wuhan)(Grant No.162301132637).
文摘The 2019 M_(S)6.0 Changning earthquake occurred in the tectonically stable Sichuan Basin,where the epicenter and its adjacent areas are important shale gas and salt mine production fields,resulting in hot debates on whether the seismogenic mechanism of the 2019 Changning earthquake is related to human activities.As source characteristics and fluid pressure can provide important constraints on whether an earthquake is induced,weinvestigate the seismogenic mechanisms of the mainshock and 9 MW≥4.0 aftershocks.In overall,the mainshock and the majority of the aftershocks are characterized by relatively shallow focal depths(1‒4 km)and significant non-double-couple(non-DC)components.However,the mainshock and the aftershocks differ in two aspects:(1)the compensated-linear-vector-dipole components dominate the non-DC components of the mainshock,whereas the isotropic components dominate the most aftershocks;(2)the fluid overpressure of the mainshock is over 30 MPa,whereas the fluid overpressure of the most aftershocks is less than 10 MPa.Thus,we propose that the mainshock is triggered by weakened fault strength with long-term fluid injection,and that its large non-DC components are associated withcomplex rupture processes.Comparatively,the aftershocks may be triggered by postseismic stress transfer by combining the Coulomb failure stress changes in the poroelastic medium.Our results highlight the possible role of fluid in the occurrence of the Changning earthquake sequence.
基金supported by the Open Fund of Hubei Luojia Laboratory(230100015)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB41000000)the Knowledge Innovation Program of Wuhan-Shuguang Project(2023010201020281).
文摘On December 18,2023,the MS 6.2 Jishishan earthquake occurred in the northeastern region of the Qinghai-Xizang Plateau,causing heavy casualties and property damage in Gansu and Qinghai Provinces.In this study,we integrate space imaging geodesy,finite fault inversion,and back-projection methods to decipher its rupture property,including fault geometry,coseismic slip distribution,rupture direction,and propagation speed.The results reveal that the seismogenic fault dips to the southwest at an angle of 29.The major slip asperity is dominated by reverse slip and is concentrated within a depth range of 7-16 km,which explains the significant uplift near the epicenter observed by both the Sentinel-1 ascending and descending InSAR data.Moreover,the teleseismic array waveforms indicate a northwest propagating rupture with an overall slow rupture velocity of~1.91 km/s(AK array)or 1.01 km/s(AU array).
基金the Project of China Earthquake Administration(Grant Nos.2019CSES0109,2018CSES0101)the National Natural Science Foundation of China(Grant Nos.41874053,42030108,41731072)+1 种基金the Fundamental Research Funds for the Central Universities,China University of Geosciences(Wuhan)(Grant Nos.162301132637,CUGCJ1707)the High-performance Computing Platform of China University of Geosciences。
文摘1.Background on the seismic gap between the Wenchuan and the Lushan earthquakes The 2008 Mw7.9 Wenchuan earthquake and the 2013 Mw6.9 Lushan earthquake,which occurred in the Longmenshan fault system(hereafter called LMSFS),caused dramatically casualties and huge economic losses.Their aftershock zones outline a seismic gap of about 50 km(Figure 1).