The 2022 M_(W)6.7 Menyuan earthquake ruptured the western end of the Tianzhu seismic gap,providing an opportunity to study the regional seismogenic characteristics and seismic hazards.Here we use interferometric synth...The 2022 M_(W)6.7 Menyuan earthquake ruptured the western end of the Tianzhu seismic gap,providing an opportunity to study the regional seismogenic characteristics and seismic hazards.Here we use interferometric synthetic aperture radar(InSAR)and seismic data to study the mainshock rupture,early afterslip and the second largest aftershock of the 2022 Menyuan earthquake sequences.Our modeling results show that the mainshock ruptured the Lenglongling fault and the Tuolaishan fault with a maximum slip of~3 m.Rapid postseismic transient deformation occurred at the center of the Lenglongling fault.Our afterslip modeling reveals that the majority of afterslip occurred in the deeper part of the Lenglongling fault.A high-angle conjugated faulting event is found at the middle section of the Lenglongling fault.We use the stress inversion to investigate the possible triggering mechanism of the conjugated rupture event.The results indicate the maximum principal stress direction is in~222°,forming a~22°angle between the conjugated fault of second largest aftershock and the mainshock.The calculated normal stress changes indicate the region is within a pull-apart stress field,which favors such a conjugated rupturing event.Our study will help understand the rupture behavior of such kind of conjugated fault in other regions.展开更多
On 22 nd May 2021(local time),an earthquake of M_(s)7.4 struck Maduo county in Qinghai Province,China.This was the largest earthquake in China since the 2008 Wenchuan earthquake.In this study,ascending/descending Sent...On 22 nd May 2021(local time),an earthquake of M_(s)7.4 struck Maduo county in Qinghai Province,China.This was the largest earthquake in China since the 2008 Wenchuan earthquake.In this study,ascending/descending Sentinel-1 and advanced land observation satellite-2(ALOS-2)synthetic aperture radar(SAR)images were used to derive the three-dimensional(3-D)coseismic displacements of this earthquake.We used the differential interferometric SAR(In SAR,DIn SAR),pixel offset-tracking(POT),multiple aperture In SAR(MAI),and burst overlap interferometry(BOI)methods to derive the displacement observations along the line-of-sight(LOS)and azimuth directions.To accurately mitigate the effect of ionospheric delay on the ALOS-2 DIn SAR observations,a polynomial fitting method was proposed to optimize range-spectrum-split-derived ionospheric phases.In addition,the 3-D displacement field was obtained by a strain model and variance component estimation(SM-VCE)method based on the high-quality SAR displacement observations.Results indicated that a left-lateral fault slip with the largest horizontal displacement of up to 2.4 m dominated this earthquake,and the small-magnitude vertical displacement with an alternating uplift/subsidence pattern along the fault trace was more concentrated in the near-fault regions.Comparison with the global navigation satellite system data indicated that the SM-VCE method can significantly improve the accuracy of the displacements compared to the classical weighted least squares method,and the incorporation of the BOI displacements can substantially benefit the accuracy of north-south displacement.In addition to the displacements,three coseismic strain invariants calculated based on the strain model parameters were also investigated.It was found that the eastern and western parts of the faults suffered more significant strains compared with the epicenter region.展开更多
Quantifying the kinematic evolution patterns of dune migration plays a major role in resisting the sand-dust disasters and evaluating the desertification process.With the increment of optical observations,measuring th...Quantifying the kinematic evolution patterns of dune migration plays a major role in resisting the sand-dust disasters and evaluating the desertification process.With the increment of optical observations,measuring the dune migration with dense spatial and temporal density has become possible.In this study,with the open-accessible Landsat-8(L8)/Sentinel-2(S2)imagery and global terrain datasets,we designed a complete workflow of inverting the dune displacement time series and velocity,identifying the potential encroachment risk,and evaluating the sediment balance of mobilized dune fields near Dunhuang Oasis.After the performance of time-series inversion,the standard deviation(STD)of measurements in stable area of raw correlation results was improved by above 40%.The displacement time series and velocity revealed out the spatial heterogeneity and seasonal/inter-annual dynamic evolution of dune migration.Furthermore,dune encroachment risk in the immediate vicinity of local landscapes was evaluated to highlight the unstable dune fields,and the workability of existent sand-control facilities.Additionally,the mass budget of around−0.001±0.025 m/yr shows the stable sediment transport in Mingsha mountain.This study case can be exemplified to lead the risk monitoring and sustainable conservation of Dunhuang region and other places controlled by similar climatic conditions.展开更多
基金the National Science Fund for Distinguished Young Scholars(No.41925016)National Key Research and Development Program(No.2022YFB3903602)+1 种基金National Natural Science Foundation of China(No.42174023)the Frontier Cross Research Project of Central South University(No.2023QYJC006).
文摘The 2022 M_(W)6.7 Menyuan earthquake ruptured the western end of the Tianzhu seismic gap,providing an opportunity to study the regional seismogenic characteristics and seismic hazards.Here we use interferometric synthetic aperture radar(InSAR)and seismic data to study the mainshock rupture,early afterslip and the second largest aftershock of the 2022 Menyuan earthquake sequences.Our modeling results show that the mainshock ruptured the Lenglongling fault and the Tuolaishan fault with a maximum slip of~3 m.Rapid postseismic transient deformation occurred at the center of the Lenglongling fault.Our afterslip modeling reveals that the majority of afterslip occurred in the deeper part of the Lenglongling fault.A high-angle conjugated faulting event is found at the middle section of the Lenglongling fault.We use the stress inversion to investigate the possible triggering mechanism of the conjugated rupture event.The results indicate the maximum principal stress direction is in~222°,forming a~22°angle between the conjugated fault of second largest aftershock and the mainshock.The calculated normal stress changes indicate the region is within a pull-apart stress field,which favors such a conjugated rupturing event.Our study will help understand the rupture behavior of such kind of conjugated fault in other regions.
基金supported by the National Key Basic Research and Development Program of China(Grant No.2018YFC1503603)the National Natural Science Foundation of China(Grant No.42030112)+3 种基金the Nature Science Foundation of Hunan Province(Grant No.2020JJ2043)the Project of Innovation-driven Plan of Central South University(Grant No.2019CX007)the Fundamental Research Funds for the Central Universities of Central South University(Grant Nos.2018zzts684 and 2019zzts011)the Hunan Provincial Innovation Foundation For Postgraduate(Grant No.CX20190067)。
文摘On 22 nd May 2021(local time),an earthquake of M_(s)7.4 struck Maduo county in Qinghai Province,China.This was the largest earthquake in China since the 2008 Wenchuan earthquake.In this study,ascending/descending Sentinel-1 and advanced land observation satellite-2(ALOS-2)synthetic aperture radar(SAR)images were used to derive the three-dimensional(3-D)coseismic displacements of this earthquake.We used the differential interferometric SAR(In SAR,DIn SAR),pixel offset-tracking(POT),multiple aperture In SAR(MAI),and burst overlap interferometry(BOI)methods to derive the displacement observations along the line-of-sight(LOS)and azimuth directions.To accurately mitigate the effect of ionospheric delay on the ALOS-2 DIn SAR observations,a polynomial fitting method was proposed to optimize range-spectrum-split-derived ionospheric phases.In addition,the 3-D displacement field was obtained by a strain model and variance component estimation(SM-VCE)method based on the high-quality SAR displacement observations.Results indicated that a left-lateral fault slip with the largest horizontal displacement of up to 2.4 m dominated this earthquake,and the small-magnitude vertical displacement with an alternating uplift/subsidence pattern along the fault trace was more concentrated in the near-fault regions.Comparison with the global navigation satellite system data indicated that the SM-VCE method can significantly improve the accuracy of the displacements compared to the classical weighted least squares method,and the incorporation of the BOI displacements can substantially benefit the accuracy of north-south displacement.In addition to the displacements,three coseismic strain invariants calculated based on the strain model parameters were also investigated.It was found that the eastern and western parts of the faults suffered more significant strains compared with the epicenter region.
基金supported by the National Key Research and Development Program of China(grant number 2019YFC1509201)the National Natural Science Foundation of China(grant numbers 41571435,41574005).
文摘Quantifying the kinematic evolution patterns of dune migration plays a major role in resisting the sand-dust disasters and evaluating the desertification process.With the increment of optical observations,measuring the dune migration with dense spatial and temporal density has become possible.In this study,with the open-accessible Landsat-8(L8)/Sentinel-2(S2)imagery and global terrain datasets,we designed a complete workflow of inverting the dune displacement time series and velocity,identifying the potential encroachment risk,and evaluating the sediment balance of mobilized dune fields near Dunhuang Oasis.After the performance of time-series inversion,the standard deviation(STD)of measurements in stable area of raw correlation results was improved by above 40%.The displacement time series and velocity revealed out the spatial heterogeneity and seasonal/inter-annual dynamic evolution of dune migration.Furthermore,dune encroachment risk in the immediate vicinity of local landscapes was evaluated to highlight the unstable dune fields,and the workability of existent sand-control facilities.Additionally,the mass budget of around−0.001±0.025 m/yr shows the stable sediment transport in Mingsha mountain.This study case can be exemplified to lead the risk monitoring and sustainable conservation of Dunhuang region and other places controlled by similar climatic conditions.
