Because only a small near-field coseismie gravity change signal remains after removal of noise from the accuracy of observations and the time and spatial resolution of the earth＇s surface gravity observation system, ...Because only a small near-field coseismie gravity change signal remains after removal of noise from the accuracy of observations and the time and spatial resolution of the earth＇s surface gravity observation system, it is difficult to verify simulations of dislocation theory. In this study, it is shown that the GS15 gravimeter, located 99.5 km from the epicenter of the Ms7.0 Lushan earthquake on April 20, 2013 at 08 ： 04 UTC ＋ 8, showed the influence of the earthquake from 2013-04-16 to 2013-04-26 after a time calibration, tide correc- tions, drift correction, period correction and relaxation correction were applied to its data. The post-seismic relaxation process of the spring in the gravimeter took approximately 430 minutes and showed a 2. 5 ×10^-8 ms^-2 gravity change. After correcting for the relaxation process, it is shown that a coseismic gravity change of approximately ＋0.59 ＋-0. 4 ~ 10-Sms-2 was observed by the GS15 gravimeter; this agrees with the simulated gravity change of approximately 0.31 ~ 10 -8 ms-2. The rate of the coseismie gravity change and the coseismic vertical displacement, as measured by one-second and one-day sampling interval GPS units, is also consistent with the theoretical rate of change. Therefore, the GS15 gravimeter at the Pixian Station observed a coseismic gravity change after the Ms7.0 Lushan earthquake. This and similar measurements could be applied to test and confirm the theory used for these simulations.展开更多
After the Yutian M_S7.3 earthquake,the authors instantly collected 1Hz high frequency data of the 4 reference stations within 350 km around the epicenter,and calculated the GNSS data with the TRACK module. The results...After the Yutian M_S7.3 earthquake,the authors instantly collected 1Hz high frequency data of the 4 reference stations within 350 km around the epicenter,and calculated the GNSS data with the TRACK module. The results showed that:( 1) The co-seismic displacement of Yutian station,about 54 km from the epicenter,is the most obvious,particularly in the EW component,with a change of about 52.5 ± 11mm,which is more than three times the mean-square error of calculating precision.( 2) In the Yutian reference station,the biggest variation in the EW component appeared within 1 minute after the earthquake.( 3) The change in the NS component is not great.展开更多
The Ms7. 3 earthquake occurred in Yutian, Xinjiang on February 12, 2014. Based on seismic waveform data before the earthquake and aftershocks of the earthquake sequence, which were recorded by the Xinjiang Regional Di...The Ms7. 3 earthquake occurred in Yutian, Xinjiang on February 12, 2014. Based on seismic waveform data before the earthquake and aftershocks of the earthquake sequence, which were recorded by the Xinjiang Regional Digital Seismic Network, this paper corrected instrument response, propagation path and site response of the S-wave recording spectra. We then calculated with genetic algorithms, on the basis of the Brune model, the source parameters of the 102 M, ≥ 3. 0 Yutian earthquake sequence, seismic moment, apparent stress and corner frequency. The results show that, seismic moment of the earthquake sequence is between 3. 46 × 10^11 -2. 08×10^15N.m, apparent stress is between 1.48 × 10^5 -1.16 ×10^6Pa, mean stress level is 0. 31MPa, and corner frequency is between 1.4-7. 1Hz in the range of 3. 0 -5. 0. By analyzing the apparent stress and corner frequency variation with time, we obtain that apparent stress of earthquakes before the Yutian Ms7. 3 earthquake was significantly higher than the aftershock sequence, but the corner frequency was significantly lower than the aftershock sequence. Apparent stress was at a high level before the main shock, which shows that the main shock zone accumulated higher stress, and then the apparent stress was reduced. The main shock occurred in the process of slow increase. Because of the release of a large amount of stress, after the Ms7. 3 earthquake, the apparent stress was gradually reduced. That was the performance of low stress fracture of aftershocks.展开更多
基金supported by the National Natural Science Foundation of China(41204058)the Running Foundation of the Gravity Network Center of China(201301008)
文摘Because only a small near-field coseismie gravity change signal remains after removal of noise from the accuracy of observations and the time and spatial resolution of the earth＇s surface gravity observation system, it is difficult to verify simulations of dislocation theory. In this study, it is shown that the GS15 gravimeter, located 99.5 km from the epicenter of the Ms7.0 Lushan earthquake on April 20, 2013 at 08 ： 04 UTC ＋ 8, showed the influence of the earthquake from 2013-04-16 to 2013-04-26 after a time calibration, tide correc- tions, drift correction, period correction and relaxation correction were applied to its data. The post-seismic relaxation process of the spring in the gravimeter took approximately 430 minutes and showed a 2. 5 ×10^-8 ms^-2 gravity change. After correcting for the relaxation process, it is shown that a coseismic gravity change of approximately ＋0.59 ＋-0. 4 ~ 10-Sms-2 was observed by the GS15 gravimeter; this agrees with the simulated gravity change of approximately 0.31 ~ 10 -8 ms-2. The rate of the coseismie gravity change and the coseismic vertical displacement, as measured by one-second and one-day sampling interval GPS units, is also consistent with the theoretical rate of change. Therefore, the GS15 gravimeter at the Pixian Station observed a coseismic gravity change after the Ms7.0 Lushan earthquake. This and similar measurements could be applied to test and confirm the theory used for these simulations.
基金founded the Projects of Science for Earthquake Resilience(XH16042Y)Project of Earthquake Science Foundation of Xinjiang,China(201501,201514)
文摘After the Yutian M_S7.3 earthquake,the authors instantly collected 1Hz high frequency data of the 4 reference stations within 350 km around the epicenter,and calculated the GNSS data with the TRACK module. The results showed that:( 1) The co-seismic displacement of Yutian station,about 54 km from the epicenter,is the most obvious,particularly in the EW component,with a change of about 52.5 ± 11mm,which is more than three times the mean-square error of calculating precision.( 2) In the Yutian reference station,the biggest variation in the EW component appeared within 1 minute after the earthquake.( 3) The change in the NS component is not great.
基金jointly sponsored by the National Key Technology R&D Program of China(2012BAK19B04-01-05)the Youth Earthquake Situation Tracking Program of China Earthquake Administration(2015010106)
文摘The Ms7. 3 earthquake occurred in Yutian, Xinjiang on February 12, 2014. Based on seismic waveform data before the earthquake and aftershocks of the earthquake sequence, which were recorded by the Xinjiang Regional Digital Seismic Network, this paper corrected instrument response, propagation path and site response of the S-wave recording spectra. We then calculated with genetic algorithms, on the basis of the Brune model, the source parameters of the 102 M, ≥ 3. 0 Yutian earthquake sequence, seismic moment, apparent stress and corner frequency. The results show that, seismic moment of the earthquake sequence is between 3. 46 × 10^11 -2. 08×10^15N.m, apparent stress is between 1.48 × 10^5 -1.16 ×10^6Pa, mean stress level is 0. 31MPa, and corner frequency is between 1.4-7. 1Hz in the range of 3. 0 -5. 0. By analyzing the apparent stress and corner frequency variation with time, we obtain that apparent stress of earthquakes before the Yutian Ms7. 3 earthquake was significantly higher than the aftershock sequence, but the corner frequency was significantly lower than the aftershock sequence. Apparent stress was at a high level before the main shock, which shows that the main shock zone accumulated higher stress, and then the apparent stress was reduced. The main shock occurred in the process of slow increase. Because of the release of a large amount of stress, after the Ms7. 3 earthquake, the apparent stress was gradually reduced. That was the performance of low stress fracture of aftershocks.
文摘引言 据中国地震台网中心测定,2014年2月12日17时19分48.3秒（北京时间）在新疆维吾尔自治区和田地区于田县（36.10°N,82.50°E）发生MS7.3地震,震源深度12 km.此次地震发生在塔里木盆地南侧,靠近西昆仑山区域边缘的阿尔金地震带,震中位于新疆与西藏交界的无人区,平均海拔5100m,地震没有造成人员伤亡.2008年3月21日于田县境内也曾发生过一次MS7.3地震,两次地震震中仅相距96 km.
