Abstract 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.
Barlik, M., and Rogowski, J. B., 1989, Variations of the plumb-line direction obtained from astronomical and gravimetric observations: Prace Nauk Politech Warsz, 33, 19-101.
[2]
Barnes, D. F., 1966, Gravity changes during the Alaska earthquake: J. Geophys. Res., 71, 451−456.
[3]
Bendat, J. S. and Piersol, A. G., 1971, Random data: Analysis and measurement procedures: Wiley-Interscience (A division of John Wiley & Sons, Inc.), New York-London-Sydney.
[4]
Bergeron, J., 1991, Transactions of the International Astronomical Union, Vol. XXIB: Proceeding of the Twenty-First General Assembly, Buenos Aires, Kluwer Academic Publishers, pp. 209.
[5]
BIH (Bureau International de l’Heure), 1984, Annual Report for 1983, Paris.
[6]
Chen, L. D., and Fu, H., 2004, Base and Experience of Earthquake Prediction (in Chinese): Seismic Press, Beijing, 33−45.
[7]
Chen, Y. T., Gu, H. D. and Lu, Z. X., 1979, Variations of gravity before and after the Haicheng earthquake, 1975, and the Tangshan earthquake, 1976: Phys. Earth Planet Interiors, 18, 330-338.
[8]
Geller, R. J., Jackson, D. D., Kagan, Y. Y. and Mulargia, F., 1997, Earthquakes cannot be predicted: Science, 275, 1616-1617.
[9]
Guo, Z. J., Han, Y. B., and Wu, J. B., 2003a, By three of the dynamic and static method to predict earthquakes criterion: Earth science frontiers (in Chinese), 10(1), 70−70.
[10]
Guo, Z. J., Han, Y. B., and Wu, J. B., 2003b, Discussion on the physical mechanism of predicting big earthquakes by means of the double method of magnetic storm: South China Journal of Seismology (in Chinese), 23(1), 38−41.
[11]
Han, Y. B., 1993, Relationship between residual anomalies of time-latitude and earthquakes: Chinese Science Bulletin, 38, 303-307.
[12]
Han, Y. B., Hu, H., and Du, H. R., 1987, Occurrence of short-period anomaly of residuals of astronomical time-latitude at Yunnan observatory preceding the Luquan earthquake (ML = 6.3): Chinese Science Bulletin, 32(17), 1205-1207.
[13]
Han, Y. B. and Tian, J., 1993, Method and application software providing information on earthquake prediction with the classical astrometric observations: publ. of Beijing Astron. Obs., 22, 41−44.
[14]
Han, Y. B., Zhang, G. D., Hu, H., and Zhao, F. S., 1994, Significance and feasibility of constructing Yunnan astronomical time-latitude seismic net: Journal of Seismological Research (in Chinese), 17(1), 1−6.
[15]
Hu, H., and Han, Y. B., 1997, Aplication of the anomaly of astrometric observations to earthquake prediction study: In Forsberg, R., Feissel, M., Dietrich, R., (eds), International association of geodesy symposia, IAG scientific assembly, Rio de Janeiro, Springer Press, 119, 460−464.
[16]
Hu, H., and Han, Y. B.,2005, Prediction of the Hualian earthquakes inTaiwanand an extended discusion on the method of commensurability:AppliedGeophysics, 2(3), 194−196
[17]
Hu, H., Han, Y., Su, Y. J., et al., 2013, Commensurability of earthquake occurrence: Journal of Asian Earth Sciences, 70−71, 27−34.
[18]
Hu, H., Kan, R. J., and Li, X. M., 1996, Application of the residuals of astronomic time and latitude in the earthquake prediction: Chinese Science Bulletin, 41(13), 1104−1106.
[19]
Hu, H., Kan, R. J., Wang, R., Cai, X., and Chen, C. X., 1989, A method for predicting a strong earthquake by means of astrometric observations: Astron Astrophys, 224, 321-322.
[20]
Hu, H., Li, Z. X., Li, H., and Fu, G. Y, 2003, Internnual variations of the vertical at Yunna by astrometry and gravimetry techniques: Journal of Natural Disasters (in Chinese), 12(2), 25−27.
[21]
Hu, H., Su, Y. J., Fu, H., Han, Y. B., Wang, R., and Ma, L. H., 2007, Anomalies in time-latitude residuals at Yunnan Observatory before Dayao and Puer earthquakes: Journal of Natural Disasters (in Chinese), 16(5), 106-110.
[22]
Hu, H., Wang, R., Kan, R. J., and Zhao, H. S., 1994, Occurrence of the short-term anomaly of residuals of astronomic time-latitude at Yunnan Observatory before the Puer earthquake: In Proceedings, International Workshop on Seismotectonics and Seismic Hazard in South East Asia, Hanoi-Vietnam, 52−56.
[23]
Kan, R. J., and Hu, H., 1995, The major earthquakes in and around Yunnan and variation of astronomical time-latitude residuals determined in Yunnan Observatory: Earthquake Res. China, 11(4), 299-309.
[24]
Kan, R. J., Zhang, S. C., Yan, F. T. and Yu, L. S., 1977, Discussion on the characteristics of the modem tectonic stress field and modern tectonic activities in Southwest China: Acta Geophysica Sinica (in Chinese), 20(2), 96−109.
[25]
Kimura, H., 1902, A new annual term in the variation of latitude independent of the components of the pole' motion: Astronomical Journal, 22, 107−108.
[26]
Kotaczel, B., 1988, Transactions of the International Astronomical Union, Vol. XXB: Proceeding of the Nineteenth General Assembly, Baltimore, Kluwer Academic Publishers, pp.197.
[27]
Liao, D. C., Jin, W. J., Zheng, D. W., and Wang, S. H., 1994, An analysis of optical observations in China during 1986 to 1991: Ann Shanghai Observatory Acad Sin. (in Chinese), 15, 28-33.
[28]
Liao, D. C., and Zheng, D. W., 1990, Earthquake (MS=5) in Taicang and anomalous residuals of time determination at Shanghai Observatory: Chinese Science Bulletin, 35(23), 1838-1839.
[29]
Li, Y., 2006, An examination of the correlation between earthquake, positions of solar system bodies and solid tide: Science in China Series G, 49(3), 367−376.
[30]
Li, Y., 2010, Modeling earthquake indexes derived from the earthquake warning system upon the planet earth: Science in China Series G, 53(12), 2293−2299.
[31]
Li, Z. S., Han, Y. B., and Tian, J., 1989, A possible geoghysical explanation for abnormal residual fluctuations of astronaomical time and latitue: Ann Shanghai Observatory Acad Sin. (in Chinese), 10, 16-22.
[32]
Li, Z. S., Han, Y. B., and Tian, J., 1991, A possible warning sign of major earthquake through observations of astronomical time and latitude: Astrophysics and Space Science, 17, 383−384.
[33]
Li, Z. S., Zhang, G. D., Zhang, H. Z., and Liu, X. J., 1978, Relationship between the short-term anomaly of astronomical time-latitude observation and the strong earthquakes around the observatory: Acta Geophysical Sinica (in Chinese), 4, 278−291.
[34]
Li, Z. X., and Li, H., 2008, Correlation between plumb line variations and earthquakes around at Tangshan during 1987 to 1998: Sci. China Ser. D-Earth Sci., 38, 432-438.
[35]
Li, Z. X., and Li, H., 2009, Earthquake-related gravity field changes at Beijing-Tangshan gravimetric network during 1987-1998: Stud. Geophys. Geodaet., 53, 185-197.
[36]
Long, X. X., Yan, J. P., Sun, H., and Wang, Z. Z., 2006, Study on earthquake tendency in Sichuan-Yunnan Region based on commensurability: Journal of Catastrophology (in Chinese), 21(3), 81-84.
[37]
Men, K. P., 1994, Study on prediction of strong earthquakes (M ≥ 7) in Xinjiang and nearby area: Northwestern Seismological Journal (in Chinese), 16(4), 29−36.
[38]
Men, K. P., and Li, D., 2000, Prediction for trend of strong earthquakes in the Southern Yellow Sea area: Northwestern Seismological Journal (in Chinese), 22(2), 134−138.
[39]
Swing, J. P., 1985, Transactions of the International Astronomical Union, Vol. XIXB: Proceeding of the Nineteenth General Assembly, Delhi, Kluwer Academic Publishers, pp.175.
Yang, X. X., and Wang, L., 1995, Earth rotation, polar migration and crustal deformation: Crustal Deformation and Earthquake (in Chinese), 15(2), 74−82.
[42]
Zhang, G. D., 1981, The variation in the vertical line caused by the activity of the underground water before a strong earthquake: Acta Seismological Sinica (in Chinese), 3(2), 152−158.
[43]
Zheng, D. W., and Zhou, Y. H., 1995, Studies of the relations between the earth rotation and global earthquake activities: Acta Seismol Sin. (in Chinese), 17, 25-30.
2016, Vol. 13 
