Abstract:In this paper, the relationship between atmosphere pressure and the four strong earthquakes occurring in north China(i. e. Xingtai, Bohai, Haicheng and Tangshan)have been studied. And it is found that the pressure change patterns in space and time before four earthquakes are much the same as follows:
1. The departure values of the monthly mean pressure in epicentral districts before earthquakes are evidently different from those of the surrounding ones. The epicenter is very close to the centre of pressure departure.
2. The values of the daily mean pressure in epicentral districts before earthquakes show a special larger change which is usually beyond 10 mb.
The above-mentioned phenomena illustrate that it is possible to have the influence of the seismic brewing process on atmosphere and the existance of trigger action.
The author thinks that these consequences can be applied to the short-term prediction.