Tell me what kind of earthquake happened in Japan and explain the reason.

The earthquake in Japan was caused by the typical active continental margin activities. Japan Island is a volcanic island arc, with a back-arc basin in the west and a Pacific plate in the east. Due to the subduction of the Pacific plate under the Asian plate, that is, in the east of Japan Island, an earthquake occurred in its east. If the nuclear power plant on the island of Japan had been built on the west coast, it might not have caused such a big nuclear leak.