Based on existing historical data and observations from the Dalian seismic station,this paper rechecks the parameters of the three historical earthquakes of 1916,1917 and 1944 in the North Yellow Sea,near the Yalu Riv...Based on existing historical data and observations from the Dalian seismic station,this paper rechecks the parameters of the three historical earthquakes of 1916,1917 and 1944 in the North Yellow Sea,near the Yalu River region.The results show that their relocated epicenters are located at contemporarily intense seismic active zones,consistent with the results derived from the data of the Dalian seismic station.The results are valuable in both revising earthquake catalogues and understanding the local background seismicity.展开更多
We firstly detected the Earth's free toroidal oscillations excited by three large earthquakes in Japan,2011,Chile,2010 and Indonesia,2005 from the observed data of the JCZ-1 seismometer at Wuhan Seismic Station. T...We firstly detected the Earth's free toroidal oscillations excited by three large earthquakes in Japan,2011,Chile,2010 and Indonesia,2005 from the observed data of the JCZ-1 seismometer at Wuhan Seismic Station. The eigenperiods of basic modes (0T2 - 0T67 ) and first modes (1T2 ～ 1T50 ) were detected,and their error ratios were less than 0. 5% by comparing the observed eigenvalues with the theoretical eigenvalues in PREM. We supplemented some modes- 0T11,0T15 , 0T19 , 1T4 , 1T5 and 1T14 ,which were not mentioned in PREM,and also observed the spectral line multi-peak phenomenon from 0T2, 0T6 , 0T7 and 0T8 . These results show that the JCZ-1 seismometer is able to precisely observe the Earth's long period toroidal free oscillations.展开更多
Several new demands have been put forward for the application of the Beijing continuous GNSS observations due to some particular reasons, such as the limited coverage of the observation network, the different construc...Several new demands have been put forward for the application of the Beijing continuous GNSS observations due to some particular reasons, such as the limited coverage of the observation network, the different construction and management criterion executed by different units and the intense interference resulting from human activity. In this paper, necessary processing of data is carried out, including more accurate calculation, corrections to the replacement, outliers and relocation of equipment, and elimination of linear trends in the E-component for every station. The E-components of the 16 available stations showed a lower sawtooth wave anomaly （slowly westward propagating） before the 2011 Tohoku Mw9. 0 earthquake, a coseismic step rebound （rapid eastward propagating） and a post-seismic D-shaped recovery. These steps constituted a complete earthquake process which was rarely seen before in the GNSS observations and provides a good example for further study. Moreover, the rapid eastward propagating during the earthquake is not influenced by the size of the given normal values, which may play a significant role in earthquake forecasting and early warning.展开更多
Near-surface earth resistivity and underground water level anomalies were recorded at Qingdao seismic observatory of Shandong Province before and after the MS8.0 Wenchuan Earthquake of May 12,2008.The observed data of...Near-surface earth resistivity and underground water level anomalies were recorded at Qingdao seismic observatory of Shandong Province before and after the MS8.0 Wenchuan Earthquake of May 12,2008.The observed data of earth resistivity at the observatory revealed that the underground water level dropped and the resistivity increased.It is postulated that in the special tectonic setting at Qingdao observatory,the variation of stress and strain caused the change of water level beneath the station,thus,leading to the variation of earth resistivity.The relationship between the variation of stress field and the change of earth resistivity before earthquake is analyzed.展开更多
基金sponsored by the Seismic Industry-specific Scientific Research(200708003),China
文摘Based on existing historical data and observations from the Dalian seismic station,this paper rechecks the parameters of the three historical earthquakes of 1916,1917 and 1944 in the North Yellow Sea,near the Yalu River region.The results show that their relocated epicenters are located at contemporarily intense seismic active zones,consistent with the results derived from the data of the Dalian seismic station.The results are valuable in both revising earthquake catalogues and understanding the local background seismicity.
基金sponsored by the Key Program of National Natural Science Foundation of China ( 40730317)
文摘We firstly detected the Earth's free toroidal oscillations excited by three large earthquakes in Japan,2011,Chile,2010 and Indonesia,2005 from the observed data of the JCZ-1 seismometer at Wuhan Seismic Station. The eigenperiods of basic modes (0T2 - 0T67 ) and first modes (1T2 ～ 1T50 ) were detected,and their error ratios were less than 0. 5% by comparing the observed eigenvalues with the theoretical eigenvalues in PREM. We supplemented some modes- 0T11,0T15 , 0T19 , 1T4 , 1T5 and 1T14 ,which were not mentioned in PREM,and also observed the spectral line multi-peak phenomenon from 0T2, 0T6 , 0T7 and 0T8 . These results show that the JCZ-1 seismometer is able to precisely observe the Earth's long period toroidal free oscillations.
基金funded by Research Foundation for Veteran Experts of China Earthquake Administration(201346)the Natural Science Foundation of Beijing Municipality(8041001,8092012)
文摘Several new demands have been put forward for the application of the Beijing continuous GNSS observations due to some particular reasons, such as the limited coverage of the observation network, the different construction and management criterion executed by different units and the intense interference resulting from human activity. In this paper, necessary processing of data is carried out, including more accurate calculation, corrections to the replacement, outliers and relocation of equipment, and elimination of linear trends in the E-component for every station. The E-components of the 16 available stations showed a lower sawtooth wave anomaly （slowly westward propagating） before the 2011 Tohoku Mw9. 0 earthquake, a coseismic step rebound （rapid eastward propagating） and a post-seismic D-shaped recovery. These steps constituted a complete earthquake process which was rarely seen before in the GNSS observations and provides a good example for further study. Moreover, the rapid eastward propagating during the earthquake is not influenced by the size of the given normal values, which may play a significant role in earthquake forecasting and early warning.
基金supported by Natural Science Fondation of Shandong Province(ZR2010DM008)National Natural Science Foundation(40534023, 41074047),China
文摘Near-surface earth resistivity and underground water level anomalies were recorded at Qingdao seismic observatory of Shandong Province before and after the MS8.0 Wenchuan Earthquake of May 12,2008.The observed data of earth resistivity at the observatory revealed that the underground water level dropped and the resistivity increased.It is postulated that in the special tectonic setting at Qingdao observatory,the variation of stress and strain caused the change of water level beneath the station,thus,leading to the variation of earth resistivity.The relationship between the variation of stress field and the change of earth resistivity before earthquake is analyzed.
