墨西哥城处于地震带，时常有小震。
Mexico city is in an earthquake zone and earth tremors are not unusual.
这可能是一个小震荡，可能是不平衡的，它将会需要一段时间，他说。
It could be a little choppy, it could be uneven, and it is going to take a while, he said.
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.
应用推荐