Study of 78 boreholes, in addition to field investigation, have been carried out in the Lonhu Lake and its coast in Jinjiang County of Fujian Province. The authors found that the formation of palaeo-river channels and the lake were all resulted from palaeo-earthquakes in the Holocene. The uplifting of the block in the lower reaches of the channels caused the formation of the Longhu Lake. In this regard, the Longhu Lake is a seismic fault blocked lake only formed in Late Holocene. The palaeo-river was formed 7 000 a B.P. in early Holocene as the result of another great earthquake which made the palaeo-forests of Shenhu Bay basin sunk for the first time into the sea. The earthquake brought about great environmental changes in the region of the Shenhuwan Bay.