火山喷发前兆，包括在实际爆发强震群和快速地面变形，通常发生几天到几周。
Precursors to volcanic eruptions include strong earthquake swarms and rapid ground deformation and typically take place days to weeks before an actual eruption.
伽师强震群的破裂断层面为北东向，与震源深度梯度变化带、地壳接触变形梯度变化带、等烈度线以及地震扩展方向吻合；
The rupture surface is to NNE, similar to gradient belt of focal depth, gradient belt of crustal deformation, isoseisms and extended direction of earthquakes.
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。
Before the moderately strong earthquakes in the region there are frequent seismic activity with magnitude of 4 or so and small earthquake swarms.
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