IMS mission to the most remote inhabited place on earth, Tristan da Cunha

In November 2001, a team from the Provisional Technical Secretariat undertook a fascinating one month mission to the remote island of Tristan da Cunha in the South Atlantic Ocean. The team carried out site survey operations for the hydroacoustic T-phase station HA09, the infrasound station IS49 and the radionuclide station RN68.

Tristan da Cunha is situated in the South Atlantic Ocean roughly half way between Cape Town and Buenos Aires. It is the most remote inhabited territory in the world. Its nearest neighbour is St. Helena, 2,334 km to the north, while Cape Town is 2,778 km to the east. The island is circular and covers an area of about 100 square kilometres, rising steeply from the sea to the 2250 metre peak which reveals the original volcano cone. The population of approximately 300 people lives in a small settlement on a plateau at the foot of the mountain. The rest of the island is mostly surrounded by 600 metre cliffs.

Tristan is accessible only by sea, and is visited by ships only on a very occasional basis. There are no ports or significant landing facilities, so all goods and passengers have to disembark in small boats. The situation in the 'Roaring Forties' latitudes makes access even more difficult.

The organization of a site survey in such a challenging environment resulted in a unique team effort which made the best use of internal Secretariat resources, complemented by ad-hoc contractors. A survey team of eight people led by a Secretariat staff member was set up, with six IMS staff from the four different technologies and two people from the British Geological Survey (BGS). The Government of the Republic of South Africa, through its Department of Environmental Affairs and Tourism (DEA&T), provided the ship SA Agulhas to transport the survey team from Cape Town to the island and back.

The transit time between Cape Town and the island was approximately five days each way. The survey team managed to stay nine precious days on Tristan da Cunha, making the best use of the time available to explore the island, deploy seismic, infrasound and radionuclide sensors, and identify, in consultation with the islanders, possible scenarios for the station installation. Despite the bad weather all three site survey operations were successful in achieving their objectives. The excellent support and interest of the island population was a great help. A presentation of the team's activities was made at the school and was very well received by the audience.

As well as the kindness of the islanders, hiking in such a remote area, climbing the slippery cliffs, riding dinghies in bad sea conditions, landing in the surf, walking past rock hopper and seal colonies and admiring the majestic flight of wandering albatross made the mission an unforgettable experience.