Good point! It would have an effect on availability of data.
This area (Bouvet) reminds me of the Vela Incident. CIA declassified the docs (still a lot of it redacted).
http://www.foia.cia.gov/docs/DOC_0000037625/DOC_0000037625.pdf
http://www.foia.cia.gov/docs/DOC_0001108246/DOC_0001108246.pdf
From Wiki: The “double flash” was detected on September 22, 1979, at 00:53 GMT, by the American Vela satellite 6911, which carried various sensors that had been designed specifically to detect nuclear explosions. In addition to being able to detect gamma rays, X-rays, and neutrons, the satellite also contained two silicon solid-state bhangmeter sensors that would be able to detect the dual light flashes associated with an atmospheric nuclear explosion: the initial brief, intense flash, followed by the second longer flash.[3]
The satellite reported the characteristic double flash of a small atmospheric nuclear explosion of two to three kilotons, in the Indian Ocean between The Crozet Islands (a very small, sparsely inhabited French possession) and the Prince Edward Islands which belong to South Africa at 47°S 40°ECoordinates: 47°S 40°E. The previous 41 double flashes that the Vela satellites detected were all subsequently confirmed to be nuclear explosions.[7]