As lower Yangtze is the continentaledge-extending area controlled by asthenolith through a long time of the research on geology of the depth, lower Yangtze area has general background of earthquake.
长期的深部地质研究证实，下扬子地区属软流圈软流控制下的陆缘伸展区，因而具有普遍的面积性地震背景。
2
It had been assumed that the ice extended westward from the Alaskan/Canadian mountains to the very edge of the continental shelf, the flat, submerged part of the continent that extends into the ocean.