The April 25, 2015 Mw7.8 Nepal earthquake was successfully recorded by Crustal Movement Observation Network of China （CMONOC） and Nepal Geodetic Array （NGA）. We processed the high-rate GPS data （1 Hz and 5 Hz） b...The April 25, 2015 Mw7.8 Nepal earthquake was successfully recorded by Crustal Movement Observation Network of China （CMONOC） and Nepal Geodetic Array （NGA）. We processed the high-rate GPS data （1 Hz and 5 Hz） by using relative kinematic positioning and derived dynamic ground motions caused by this large earthquake. The dynamic displacements time series clearly indicated the displacement amplitude of each station was related to the rupture directivity. The stations which located in the di- rection of rupture propagation had larger displacement amplitudes than others. Also dynamic ground displacement exceeding 5 cm was detected by the GPS station that was 2000 km away from the epicenter. Permanent coseismic displacements were resolved from the near-field high-rate GPS stations with wavelet decomposition-reconstruction method and P-wave arrivals were also detected with S transform method. The results of this study can be used for earthquake rupture process and Earthquake Early Warning studies.展开更多
Based on the total electron content （TEC） derived from Global Positioning System （GPS） observations of the Crustal Movement Observation Network of China （CMONOC） and the Global Ionosphere Map （GIM） from the Ce...Based on the total electron content （TEC） derived from Global Positioning System （GPS） observations of the Crustal Movement Observation Network of China （CMONOC） and the Global Ionosphere Map （GIM） from the Center for Orbit Determination in Europe （CODE）, we detected and analyzed the ionospheric variations during the 2015 M7.8 Nepal earthquake （including the pre-earthquake ionospheric anomalies and coseismic ionospheric disturbances （CIDs） following the main shock）. The analysis of vertical total electron content （VTEC） time series shows that the large-scale ionospheric anomalies appeared near the epicenter two days prior to the earthquake. Moreover, the pre-earthcluake ionospheric anomalies were also observed in the geomagnetically conjugated region. In view of solar-terrestrial environment, the pre-earthquake ionospheric anomalies could be associated with the Nepal earthquake. In addition, we also detected the CIDs through the high-frequency GPS observation stations. The CIDs had obvious oscillated waveforms with the peak-to-peak disturbance amplitudes of about I TECu and 0.4 TECu, which propagated approximately with the horizontal velocities of 877 ±75 m/s and 319 ± 30 m/s, respectively. The former is triggered directly by the acoustic waves which originated from the energy release of the earthquake near the epicenter, while the latter could be stimulated by the acoustic-gravity waves from the partial transformation of the acoustic waves.展开更多
The M7.9 Nepal earthquake of 25 April2015 had over 8, 500 fatalities and was the most destructive earthquake in Nepal since the Bihar-Nepal earthquake in 1934.In this study, we imaged the rupture process of this Nepal...The M7.9 Nepal earthquake of 25 April2015 had over 8, 500 fatalities and was the most destructive earthquake in Nepal since the Bihar-Nepal earthquake in 1934.In this study, we imaged the rupture process of this Nepal event by back-projecting the teleseismic P-wave energy recorded at the three regional networks in Alaska, Australia and Europe. The back-projection images of the three subarrays revealed that the Nepal earthquake propagated along the strike in a southeast direction over a distance of ～ 160–170 km with the duration of ～ 50–55 s. The rupture process was found to be a simple, unilateral event with a near constant velocity of 3.3 km/s.The beam power was mainly distributed in the geographic region just north of Kathmandu and the peak intensity for the source time function curve occurred at about 30 s. The earthquake was destructive due to its occurrence at shallow depth(～ 12–15 km) and the fact that the capital lies in a basin of soft sediment. Additionally, the resonance effect for the longer period waves that occurred in the Kathmandu valley led to destructive aggravation, impacting mainly the taller buildings.展开更多
The 2016 MW7.8 Kaikoura earthquake struck the northern part of south Island,New Zealand,within the active and complex Australia-Pacific plate boundary system.Firstly,we used the InSAR method to obtain coseismic LOS de...The 2016 MW7.8 Kaikoura earthquake struck the northern part of south Island,New Zealand,within the active and complex Australia-Pacific plate boundary system.Firstly,we used the InSAR method to obtain coseismic LOS deformation fields based on SAR images and applied offset tracking methods to obtain offset measurements based on optical satellite images.The maximum displacement of about 6 m is detected in the direction away from the satellite on the south-west side and also towards the satellite on the north-east side.The 3D deformation field is then resolved by the combination of these measurements with a least-square solve method,and comparisons with 3 components of GPS stations show good consistency.Despite complex features demonstrated in the 3D deformation field,there are still clear spatial correlations between surface deformation and faults distribution.It reveals that more than ten faults were ruptured during the earthquake,including some faults were previously understudies for their tectonic activities.The maximum horizontal deformation of about 10 m occurs along the Kekerengu fault with the vertical deformation up to 2 m.The 3D deformation shows that the mainshock is a multisegments faulting with a rupture process of strike-slip,compression,transpressional rupture and strike-slip in space along the NE direction.展开更多
On November 13, 2016, an MW7.8 earthquake struck Kaikoura in South Island of New Zealand. By means of back-projection of array recordings, ASTFs-analysis of global seismic recordings, and joint inversion of global sei...On November 13, 2016, an MW7.8 earthquake struck Kaikoura in South Island of New Zealand. By means of back-projection of array recordings, ASTFs-analysis of global seismic recordings, and joint inversion of global seismic data and co-seismic In SAR data, we investigated complexity of the earthquake source. The result shows that the 2016 MW7.8 Kaikoura earthquake ruptured about 100 s unilaterally from south to northeast(~N28°–33°E), producing a rupture area about 160 km long and about 50 km wide and releasing scalar moment 1.01×1021 Nm. In particular, the rupture area consisted of two slip asperities, with one close to the initial rupture point having a maximal slip value ~6.9 m while the other far away in the northeast having a maximal slip value ~9.3 m. The first asperity slipped for about 65 s and the second one started 40 s after the first one had initiated. The two slipped simultaneously for about 25 s.Furthermore, the first had a nearly thrust slip while the second had both thrust and strike slip. It is interesting that the rupture velocity was not constant, and the whole process may be divided into 5 stages in which the velocities were estimated to be 1.4 km/s, 0 km/s, 2.1 km/s, 0 km/s and 1.1 km/s, respectively. The high-frequency sources distributed nearly along the lower edge of the rupture area, the highfrequency radiating mainly occurred at launching of the asperities, and it seemed that no high-frequency energy was radiated when the rupturing was going to stop.展开更多
A powerful earthquake of moment magnitude(Mw)7.8occurred in the Kaikoura region,South Island,New Zealand,at00:02:56 AM(local time),14 November 2016.According to the Institute of Geological and Nuclear Sciences(GNS)in ...A powerful earthquake of moment magnitude(Mw)7.8occurred in the Kaikoura region,South Island,New Zealand,at00:02:56 AM(local time),14 November 2016.According to the Institute of Geological and Nuclear Sciences(GNS)in New Zealand,展开更多
基金supported by Director Foundation of Institute of Seismology,China Earthquake Administration(IS201426142)National Natural Science Foundation of China(41541029,41574017, 41274027)+1 种基金Natural Science Foundation of HuBei Province (2015CFB642)provided by Crustal Movement Observation Network of China(CMONOC) and UNAVCO
文摘The April 25, 2015 Mw7.8 Nepal earthquake was successfully recorded by Crustal Movement Observation Network of China （CMONOC） and Nepal Geodetic Array （NGA）. We processed the high-rate GPS data （1 Hz and 5 Hz） by using relative kinematic positioning and derived dynamic ground motions caused by this large earthquake. The dynamic displacements time series clearly indicated the displacement amplitude of each station was related to the rupture directivity. The stations which located in the di- rection of rupture propagation had larger displacement amplitudes than others. Also dynamic ground displacement exceeding 5 cm was detected by the GPS station that was 2000 km away from the epicenter. Permanent coseismic displacements were resolved from the near-field high-rate GPS stations with wavelet decomposition-reconstruction method and P-wave arrivals were also detected with S transform method. The results of this study can be used for earthquake rupture process and Earthquake Early Warning studies.
基金supported by National Natural Science Foundation of China (41174030,41304047)
文摘Based on the total electron content （TEC） derived from Global Positioning System （GPS） observations of the Crustal Movement Observation Network of China （CMONOC） and the Global Ionosphere Map （GIM） from the Center for Orbit Determination in Europe （CODE）, we detected and analyzed the ionospheric variations during the 2015 M7.8 Nepal earthquake （including the pre-earthquake ionospheric anomalies and coseismic ionospheric disturbances （CIDs） following the main shock）. The analysis of vertical total electron content （VTEC） time series shows that the large-scale ionospheric anomalies appeared near the epicenter two days prior to the earthquake. Moreover, the pre-earthcluake ionospheric anomalies were also observed in the geomagnetically conjugated region. In view of solar-terrestrial environment, the pre-earthquake ionospheric anomalies could be associated with the Nepal earthquake. In addition, we also detected the CIDs through the high-frequency GPS observation stations. The CIDs had obvious oscillated waveforms with the peak-to-peak disturbance amplitudes of about I TECu and 0.4 TECu, which propagated approximately with the horizontal velocities of 877 ±75 m/s and 319 ± 30 m/s, respectively. The former is triggered directly by the acoustic waves which originated from the energy release of the earthquake near the epicenter, while the latter could be stimulated by the acoustic-gravity waves from the partial transformation of the acoustic waves.
基金supported by the National Natural Science Foundation of China (No.41604049)
文摘The M7.9 Nepal earthquake of 25 April2015 had over 8, 500 fatalities and was the most destructive earthquake in Nepal since the Bihar-Nepal earthquake in 1934.In this study, we imaged the rupture process of this Nepal event by back-projecting the teleseismic P-wave energy recorded at the three regional networks in Alaska, Australia and Europe. The back-projection images of the three subarrays revealed that the Nepal earthquake propagated along the strike in a southeast direction over a distance of ～ 160–170 km with the duration of ～ 50–55 s. The rupture process was found to be a simple, unilateral event with a near constant velocity of 3.3 km/s.The beam power was mainly distributed in the geographic region just north of Kathmandu and the peak intensity for the source time function curve occurred at about 30 s. The earthquake was destructive due to its occurrence at shallow depth(～ 12–15 km) and the fact that the capital lies in a basin of soft sediment. Additionally, the resonance effect for the longer period waves that occurred in the Kathmandu valley led to destructive aggravation, impacting mainly the taller buildings.
基金co-supported by the National Key Research and Development Program of China(Grant No.2019YFC1509204)the National Nonprofit Fundamental Research Grant of China,Institute of Geology,China Earthquake Administration(Grant No.IGCEA2005 and No.IGCEA2014)the National Science Foundation of China(Grant No.41631073)
文摘The 2016 MW7.8 Kaikoura earthquake struck the northern part of south Island,New Zealand,within the active and complex Australia-Pacific plate boundary system.Firstly,we used the InSAR method to obtain coseismic LOS deformation fields based on SAR images and applied offset tracking methods to obtain offset measurements based on optical satellite images.The maximum displacement of about 6 m is detected in the direction away from the satellite on the south-west side and also towards the satellite on the north-east side.The 3D deformation field is then resolved by the combination of these measurements with a least-square solve method,and comparisons with 3 components of GPS stations show good consistency.Despite complex features demonstrated in the 3D deformation field,there are still clear spatial correlations between surface deformation and faults distribution.It reveals that more than ten faults were ruptured during the earthquake,including some faults were previously understudies for their tectonic activities.The maximum horizontal deformation of about 10 m occurs along the Kekerengu fault with the vertical deformation up to 2 m.The 3D deformation shows that the mainshock is a multisegments faulting with a rupture process of strike-slip,compression,transpressional rupture and strike-slip in space along the NE direction.
基金supported by the NSFC project (41474046)the DQJB project (DQJB16B05) of the Institute of Geophysics, CEA
文摘On November 13, 2016, an MW7.8 earthquake struck Kaikoura in South Island of New Zealand. By means of back-projection of array recordings, ASTFs-analysis of global seismic recordings, and joint inversion of global seismic data and co-seismic In SAR data, we investigated complexity of the earthquake source. The result shows that the 2016 MW7.8 Kaikoura earthquake ruptured about 100 s unilaterally from south to northeast(~N28°–33°E), producing a rupture area about 160 km long and about 50 km wide and releasing scalar moment 1.01×1021 Nm. In particular, the rupture area consisted of two slip asperities, with one close to the initial rupture point having a maximal slip value ~6.9 m while the other far away in the northeast having a maximal slip value ~9.3 m. The first asperity slipped for about 65 s and the second one started 40 s after the first one had initiated. The two slipped simultaneously for about 25 s.Furthermore, the first had a nearly thrust slip while the second had both thrust and strike slip. It is interesting that the rupture velocity was not constant, and the whole process may be divided into 5 stages in which the velocities were estimated to be 1.4 km/s, 0 km/s, 2.1 km/s, 0 km/s and 1.1 km/s, respectively. The high-frequency sources distributed nearly along the lower edge of the rupture area, the highfrequency radiating mainly occurred at launching of the asperities, and it seemed that no high-frequency energy was radiated when the rupturing was going to stop.
基金supported by the Earth Observatory of Singapore(EOS)Nanyang Technological University through its funding from the National Research Foundation Singapore and the Singapore Ministry of Education under the Research Centers of Excellence initiative
文摘A powerful earthquake of moment magnitude(Mw)7.8occurred in the Kaikoura region,South Island,New Zealand,at00:02:56 AM(local time),14 November 2016.According to the Institute of Geological and Nuclear Sciences(GNS)in New Zealand,
