The South Sandwich Islands () is a chain of uninhabited volcanic islands in the southern Atlantic Ocean. They are administered as part of the British Overseas Territory of South Georgia and South Sandwich Islands. The chain lies in the Subantarctic region, about southeast of South Georgia and northeast from the tip of the Antarctic Peninsula. The archipelago comprises 11 main islands forming an island arc running north–south, the largest being Montagu at . It is divided into four groups, from north to south: Traversay Islands, Candlemas Islands, Central Islands and Southern Thule. The archipelago is prone to violent earthquakes. Over the previous century, nine M 7+ earthquakes occurred, most recent being the M 8.1 in August 2021. None of these earthquakes are known to have caused fatalities due to their remote location. History The southern eight islands of the Sandwich Islands Group were discovered by James Cook in 1775; the northern three by Fabian Gottlieb von Bellingshausen in 1819.[clarification needed] Departing from South Georgia, Captain Cook sailed to the southeast to discover Clerke Rocks and a group of islands which he named "Sandwich Land" in honour of Lord Sandwich, then First Lord of the Admiralty. The word "South" was later added to distinguish them from the "Sandwich Islands", now known as Hawai'i. The Traversay Islands (Zavodovski, Leskov and Visokoi) discovered by the Imperial Russian Navy expedition of Bellingshausen and Lazarev in the ships Vostok and Mirny in 1819. The United Kingdom formally annexed the South Sandwich Islands through the 1908 Letters Patent, grouping them with other British-held territory in Antarctica as the Falkland Islands Dependencies. Argentina claimed the South Sandwich Islands in 1938, and challenged British sovereignty in the Islands on several occasions. From 25 January 1955 through summer of 1956 Argentina maintained the summer station Teniente Esquivel at Ferguson Bay on the southeastern coast of Thule Island. From 1976 to 1982, Argentina maintained a naval base named Corbeta Uruguay in the lee (southern East coast) of the same island. Although the British discovered the presence of the Argentine base in 1976, protested and tried to resolve the issue by diplomatic means, no effort was made to remove them by force until after the Falklands War. The base was eventually removed on 20 June 1982 and the installations demolished in December. Since 1995 the South African Weather Bureau maintains two automatic weather stations on the islands of Zavodovski and Thule.