The geophysical mechanism behind astronomical time-latitude residuals （ATLR） are discussed. The photoelectric astrolabe at Yunnan Observatory （YO） observed apparent synchronous anomalous ATLR before the Wenchuan M...The geophysical mechanism behind astronomical time-latitude residuals （ATLR） are discussed. The photoelectric astrolabe at Yunnan Observatory （YO） observed apparent synchronous anomalous ATLR before the Wenchuan M8.0 earthquake （EQ） in May 12, 2008 and the Lushan M7.0 EQ n April 20, 2013. We compared the ATLR from the YO photoelectric astrolabe and EQ data since 1976. Anomalous ATLR was observed before several strong EQs in the Yunnan Province. We believe the photoelectric astrolabe can be used to predict strong EQs and the anomalous ATLR are a potential EQ precursor.展开更多
The Shanxi reservoir earthquakes are significant seismic events in southern Zhejiang Province in recent years, an area with fewer and weaker earthquakes. The seismicity showed an intermittent characteristic and group ...The Shanxi reservoir earthquakes are significant seismic events in southern Zhejiang Province in recent years, an area with fewer and weaker earthquakes. The seismicity showed an intermittent characteristic and group distribution. The epicenters located by the seismic network did not show a predominant direction and the seismogenic structure is not clear. In the study, the nonlinear imaginary wave travel time equation was linearized and solved, and the source position, initial imaginary velocity and travel time residuals were obtained. Then by doubling the standard deviation as time residuals, the maximum error generated from longitude, latitude, depth and imaginary velocity was calculated. The genetic population was structured using the maximum error and the end result of earthquake location was obtained by genetic algorithm. The result of relocation of the Shanxi reservoir earthquakes with this method shows that earthquakes are largely concentrated on a near-vertical, northwest oriented fault plane, and the included angles between the normal of the plane and the due north, due east and vertical directions are 46~, 44~, and 87~, respectively. The result is in agreement with that of comprehensive fault plane solutions of small earthquakes. The average depth of the earthquakes was 4.7km, the maximum depth 9.5kin, and the minimum depth 1.7km. The epicenters showed a northwestward narrow banded distribution, and the focal depth increased along the northwest direction. There was a discontinuous seismic gap of about 3.5km long at the northwest end of the strip. The characteristics of source parameters obtained by using the Borun model were not significantly different from that of tectonic earthquakes. Seismic stress drop was about 0.33MPa, and the average stress drop was 0.88MPa. According to the stress drop＇ spatial distribution, the seismic discontinuities segment at the northwest end of the strip is in a low stress drop zone.展开更多
This paper introduces the discovery of the phenomenon that short-term anomalous fluctuations appeared in residuals of astronomical time and latitude observations before earthquakes and the progress of related research...This paper introduces the discovery of the phenomenon that short-term anomalous fluctuations appeared in residuals of astronomical time and latitude observations before earthquakes and the progress of related researches carried out for many years.The relations between the anomalous variations of time and latitude residuals of astronomical time and latitude instruments in different regions and the earthquakes around these instruments as well as the characteristics of residuals' anomalous variations are analyzed.The significance of the anomalous fluctuations in residuals of astronomical time and latitude caused by the anomalous variations of the local plumb line before earthquake and detecting the vertical variation with astronomical time and latitude observations as well as the importance of carrying out further researches are discoursed.The possibility that the phenomenon will become an effective short-term earthquakes precursor,the current situations and the problems to be solved,are discussed.Also we offer the proposals to develop new roboticized astrometric instruments with high-precision and set up test observation networks in earthquake-prone areas in order to do research in-depth,optimize methods of observing and extracting anomalous information for short-term earthquake prediction,and so on.展开更多
基金supported by the Ministry of Science and Technology of P.R.China(No.2012BAK19B01-07)
文摘The geophysical mechanism behind astronomical time-latitude residuals （ATLR） are discussed. The photoelectric astrolabe at Yunnan Observatory （YO） observed apparent synchronous anomalous ATLR before the Wenchuan M8.0 earthquake （EQ） in May 12, 2008 and the Lushan M7.0 EQ n April 20, 2013. We compared the ATLR from the YO photoelectric astrolabe and EQ data since 1976. Anomalous ATLR was observed before several strong EQs in the Yunnan Province. We believe the photoelectric astrolabe can be used to predict strong EQs and the anomalous ATLR are a potential EQ precursor.
基金supported by the Science andTechnology Project of Zhejiang Province(2007C330060)the Special Research Fund for Seismic Industry of China Seismological Bureau(200808068)
文摘The Shanxi reservoir earthquakes are significant seismic events in southern Zhejiang Province in recent years, an area with fewer and weaker earthquakes. The seismicity showed an intermittent characteristic and group distribution. The epicenters located by the seismic network did not show a predominant direction and the seismogenic structure is not clear. In the study, the nonlinear imaginary wave travel time equation was linearized and solved, and the source position, initial imaginary velocity and travel time residuals were obtained. Then by doubling the standard deviation as time residuals, the maximum error generated from longitude, latitude, depth and imaginary velocity was calculated. The genetic population was structured using the maximum error and the end result of earthquake location was obtained by genetic algorithm. The result of relocation of the Shanxi reservoir earthquakes with this method shows that earthquakes are largely concentrated on a near-vertical, northwest oriented fault plane, and the included angles between the normal of the plane and the due north, due east and vertical directions are 46~, 44~, and 87~, respectively. The result is in agreement with that of comprehensive fault plane solutions of small earthquakes. The average depth of the earthquakes was 4.7km, the maximum depth 9.5kin, and the minimum depth 1.7km. The epicenters showed a northwestward narrow banded distribution, and the focal depth increased along the northwest direction. There was a discontinuous seismic gap of about 3.5km long at the northwest end of the strip. The characteristics of source parameters obtained by using the Borun model were not significantly different from that of tectonic earthquakes. Seismic stress drop was about 0.33MPa, and the average stress drop was 0.88MPa. According to the stress drop＇ spatial distribution, the seismic discontinuities segment at the northwest end of the strip is in a low stress drop zone.
文摘This paper introduces the discovery of the phenomenon that short-term anomalous fluctuations appeared in residuals of astronomical time and latitude observations before earthquakes and the progress of related researches carried out for many years.The relations between the anomalous variations of time and latitude residuals of astronomical time and latitude instruments in different regions and the earthquakes around these instruments as well as the characteristics of residuals' anomalous variations are analyzed.The significance of the anomalous fluctuations in residuals of astronomical time and latitude caused by the anomalous variations of the local plumb line before earthquake and detecting the vertical variation with astronomical time and latitude observations as well as the importance of carrying out further researches are discoursed.The possibility that the phenomenon will become an effective short-term earthquakes precursor,the current situations and the problems to be solved,are discussed.Also we offer the proposals to develop new roboticized astrometric instruments with high-precision and set up test observation networks in earthquake-prone areas in order to do research in-depth,optimize methods of observing and extracting anomalous information for short-term earthquake prediction,and so on.
