Optical observations from a ground-based astrometric instrument provide a unique set of data sensi- tive to variations of local plumb line, which represent the change of local gravitational field on the ground. The lo...Optical observations from a ground-based astrometric instrument provide a unique set of data sensi- tive to variations of local plumb line, which represent the change of local gravitational field on the ground. The local gravitational change could be caused by density variation or movement of underground mass in addition to tidal action. Earthquake was found to be related with gravitational change. A seismic zone could have abnor- mal underground material density, causing the variation of plume line on the ground. In this frame, the astro- metric telescope can measure the variation of local plumb line by observing the local astronomical longitudes and latitudes from stars in the Hipparcos catalog. In this study, we estimate the deflection angle of the plumb line on a ground site, and give a relation be- tween the angle, abnormal mass and site distance （depth and horizontal distance）. Then we derive the abnor- mality of underground material density using the plumb lines measured at different sites, and study the earth- quake gestation, development and occurrence. Using the deflection angles of plumb lines observed at two sites, we give a method to calculate the mass and the center of gravity of underground materials. We also esti- mate the abnormal masses of latent seismic zones with different energy, using thermodynamic relations, and in- troduce a new optical astrometric instrument we had developed.展开更多
Plumb line variations(PLV) at Tangshan during the years of 1987―1998 are determined by using the 46 batch repeated gravity observations of the Beijing-Tangshan network.It has been found that PLV at Tangshan are relat...Plumb line variations(PLV) at Tangshan during the years of 1987―1998 are determined by using the 46 batch repeated gravity observations of the Beijing-Tangshan network.It has been found that PLV at Tangshan are related with the 38 earthquakes in this period.It appears that the time of an earthquake around Tangshan is usually quite the same when PLV at Tangshan begins moving in opposite direction.展开更多
基金supported by the National Natural Science Foundation of China(11163006,11173054)the National Basic Research Program of China(973 Program 2009 CB824800)the Policy Research Program of Chinese Academy of Sciences(KJCX2-YW-T24)
文摘Optical observations from a ground-based astrometric instrument provide a unique set of data sensi- tive to variations of local plumb line, which represent the change of local gravitational field on the ground. The local gravitational change could be caused by density variation or movement of underground mass in addition to tidal action. Earthquake was found to be related with gravitational change. A seismic zone could have abnor- mal underground material density, causing the variation of plume line on the ground. In this frame, the astro- metric telescope can measure the variation of local plumb line by observing the local astronomical longitudes and latitudes from stars in the Hipparcos catalog. In this study, we estimate the deflection angle of the plumb line on a ground site, and give a relation be- tween the angle, abnormal mass and site distance （depth and horizontal distance）. Then we derive the abnor- mality of underground material density using the plumb lines measured at different sites, and study the earth- quake gestation, development and occurrence. Using the deflection angles of plumb lines observed at two sites, we give a method to calculate the mass and the center of gravity of underground materials. We also esti- mate the abnormal masses of latent seismic zones with different energy, using thermodynamic relations, and in- troduce a new optical astrometric instrument we had developed.
基金Supported by the National Natural Science Foundation of China (Grant No.10633030)
文摘Plumb line variations(PLV) at Tangshan during the years of 1987―1998 are determined by using the 46 batch repeated gravity observations of the Beijing-Tangshan network.It has been found that PLV at Tangshan are related with the 38 earthquakes in this period.It appears that the time of an earthquake around Tangshan is usually quite the same when PLV at Tangshan begins moving in opposite direction.
