It has been primarily confirmed that before the occurrence of a middle or major earthquake, anomalies in the residuals of universal time and latitude measurements obtained by astrometric observations may appear. We investigate the relation between the residual anomalies and the three key factors of an earthquake. To build a network of observational sites so as to obtain data of residuals of universal time and latitude from multi-instruments would be of certain significance for determining three key factors of an earthquake, especially for positioning epicenter. The data from multi-instruments would also be valuable for studies of the variation of the vertical. It is proposed to manufacture potable and high-accuracy astrometric instruments and to build observational network to obtain anomalies of universal time and latitude in the regions with high earthquake uprising possibilities.
A lot of slow fluctuations of water level have been observed in the original recording maps of subsurface fluid in Well Shuozhou, Shanxi Province. Some typical recording maps of the 'precursors' are introduced in the paper and the features of the 'precursors' recorded by the well are analyzed. The results show that 38% strong earthquakes possess this kind of record, which has a fluctuation period arranging from several to tens of minutes and appear mostly two days before the earthquakes. Moreover, the mechanism, transmission and responding conditions of well water level are discussed, as well as the scientific meaning and practical value of the 'precursor' of the well water level in earthquake predictions.
Using the length-of-day (LOD) data series de-rived from astronomical observations made by various mod-ern space techniques, southern oscillation index (SOI) and anomalies of sea surface temperature (SST) in tropical Pa-cific Ocean, the inter-annual components of these data series are obtained by the technique of band filtering from January 1962 to October 2002. It is found that a new ENSO event has already occurred in 2002 and been detected by the inter- annual LOD. It is shown by the wavelet analysis that the component with a period of about 46 years and the quasi-biennial component are out of phase during 2001 2002, which consequently suggests that the new ENSO event cannot be a strong one.
