Sensitivities of responses of well water levels to different kinds of stress-st rain are worked out from the tidal effects of well water level, loading effects of surface water body and trains of Fengzhen well. The results represent as 6.6 ×10-9 bulk strain/mm, 9.6×10-7 bulk strain/mm and 1.0×10- 2 bulk strain/mm respectively.

According to the experimental results the authors discussed the influence of lithology, structure, confining pressure, primary pore pressure and deformation rate on the earthquake-reflecting features of well water level.

Based on the research results obtained from the observations of flow pattern in the valve region, well water level variation, cavitation characteristics of flow behind the valve, lifting and downpull loads and their fluctuations during the valve operating, it could be concluded that this kind tainter values are feasible for the TGPs middle stage locks and there still exist some special advantages in comparison with the reverse tainter valves.

These data were observed from 1970 through 1981.Results of filtering indicate that well water level anomalous changes in Tianjin area have continued about 2-3 years before the Tangshan earthquake.

On the basis of the solutions of partial differential equation of the effect of earth tide and barometric pressures on the well water level of confined aquifers under the condition of non-drainage, this paper analyzes the quantitative relationship between the earth tide effect of well water level and the barometric pressure effect and the parameters of confined aquifers.

The result shows that the larger the radius of the well casing, the porosity and the bulk compressibility of solid matrix of the aquifer, and the smaller the permeability of it, the smaller is the tidal coefficient of well water level;

In this paper,considering well pressure as a boundary condition, the diffusion equations of artesian well water level tide better accorded with the actual situation and a more perfect theoretical relational expression between tide generation force and water level tide are obtained.

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.

Compared this equation with Boulton equation used in the unconfined aquifer, a new lagging supply water term is obtained, which establish the physical basis for interpreting the phase delay phenomena of well water level caused by the solid tide.

Theoretic analysis on phase delay phenomena of well water level tide in the double medium aquifer model

Using the faltung filtering and polynary regression, considering the effect of the rain on the well water level with the lag "memory", the correction of the influence of the rain on the well water level is made.

Quantitative correction of influence of rain on well water level

By use of Kalman filtering for signal detection, data of seventeen well water levels before and after Tangshan earthquake of July 28, 1976 were analysed. These data were observed from 1970 through 1981.Results of filtering indicate that well water level anomalous changes in Tianjin area have continued about 2-3 years before the Tangshan earthquake. Anomalous changes seem to be spreading with a speed of about 3-4 km per month. The well water levels in Beijing area did not show conspicuous anomalous...

By use of Kalman filtering for signal detection, data of seventeen well water levels before and after Tangshan earthquake of July 28, 1976 were analysed. These data were observed from 1970 through 1981.Results of filtering indicate that well water level anomalous changes in Tianjin area have continued about 2-3 years before the Tangshan earthquake. Anomalous changes seem to be spreading with a speed of about 3-4 km per month. The well water levels in Beijing area did not show conspicuous anomalous changes. These anomalous changes disappeared after the Tangshan earthquake.The Transition matrix and control term in our filter are functions of time t, so that this method is applicable to real processing of seismic precursoty data specially.

Atm. pressure coefficient of well water level serves as an important index indicating the atm. pressure effects on the well, water level and the sensitivity by which the well water level responds to the stress-strain variations. Based on data obtained at the well networks deployed in China for seismological ground water observations and using statistic approaches, this paper comprehensively analyzes the factors affecting the atm. pressure eoefficent of the water...

Atm. pressure coefficient of well water level serves as an important index indicating the atm. pressure effects on the well, water level and the sensitivity by which the well water level responds to the stress-strain variations. Based on data obtained at the well networks deployed in China for seismological ground water observations and using statistic approaches, this paper comprehensively analyzes the factors affecting the atm. pressure eoefficent of the water level. Discussions are emphatically made on such a much-argued problem: if taking the same well, the atm. pressure coefficient should be a constant or a variable? Through detailed analysis, this paper reaches the conclusion that atm. pressure coefficient should be a variable. Result of this paper might provide helpful references for selecting well sites aimed at seismo-logical ground water observations as well as ways by which to eliminate the atm. pressure noises from the observed water level values.

This paper discusses the characteristics and reasons of well water level fluctuations in Shandong province during earthquakes and the abnormal variations of well water level before the shocks. Based on the relationship between the fluctuation amplitude (L), the duration (T) of the Lu 10 well and the earthquake magnitude (Ms), the following formula is obtained:MT=0.045L + 0.02T/2+0.0△+6.0Result of the study shows magnitude evaluated by the formula conforms with that cited from earthquake catalogues...

This paper discusses the characteristics and reasons of well water level fluctuations in Shandong province during earthquakes and the abnormal variations of well water level before the shocks. Based on the relationship between the fluctuation amplitude (L), the duration (T) of the Lu 10 well and the earthquake magnitude (Ms), the following formula is obtained:MT=0.045L + 0.02T/2+0.0△+6.0Result of the study shows magnitude evaluated by the formula conforms with that cited from earthquake catalogues within an error as small as 0.1 magnitude. The calculations is simple and convenient, and can thus be applied to other wells for earthquake magnitude calculations. Therefore, this method can possibly be used for the calculation of earthquake magnitude of events occurred worldwide.