What was the initial magnitude of the earthquake that formed Lake Isom?
Lake Isom Lake Isom is a small natural lake located in Lake County, Tennessee immediately south of Reelfoot Lake. It is fed by Running Reelfoot Bayou, the outlet stream of Reelfoot Lake. Like Reelfoot, it was formed in the 1811–12 New Madrid earthquakes and it is very shallow and swampy. The entire lake and its environs, covering 1,846 acres (747 ha) comprise the Lake Isom National Wildlife Refuge and have been such since 1938.
1707 Hōei earthquake The 1707 Hōei earthquake ("Hōei jishin" 宝永地震 ) struck south-central Japan at 14:00 local time on October 28, 1707. It was the largest earthquake in Japanese history until the 2011 Tōhoku earthquake surpassed it. It caused moderate to severe damage throughout southwestern Honshu, Shikoku and southeastern Kyūshū. The earthquake, and the resulting destructive tsunami, caused more than 5,000 casualties. This event ruptured all of the segments of the Nankai megathrust simultaneously, the only earthquake known to have done this, with an estimated magnitude of 8.6 M. It might also have triggered the last eruption of Mount Fuji 49 days later.