Before the moderately strong earthquakes in the region there are frequent seismic activity with magnitude of 4 or so and small earthquake swarms.
华南地区在中强震发生前有4级左右地震频繁活动和小震群频发的特点。
The results show that the tectonic environment shear stress field in Guangdong area is low on the whole, so the possibility of occurring moderately strong earthquake is small.
结果表明，广东地区的总体剪应力值较低，未来发生中强地震的可能性不大。
The calculated results of six moderately strong earthquakes in North China where the earthquake-monitoring ability is stronger have been shown in this paper, and the effectiveness is good.
文中列举了对华北地区台网具有监测能力的区域内发生的几次中强地震的计算结果，取得了良好的效果。
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