A partly cloudy ASTER satellite image from 3 November appeared to indicate that large-scale effusive activity from the summit of Montagu Island (Mt. Belinda) had ceased. The image showed that the 3.5-km-long lava flow noted in previous reports (observed entering the sea in an image from 23 September 2005) had extended the shoreline on the N side of island. The new land extended approximately 500 m from the previous shoreline, and was ~400 m wide, equating to a total area of 0.2 square kilometers.

Geological Summary. The largest of the South Sandwich Islands, Montagu consists of a massive shield volcano cut by a 6-km-wide ice-filled summit caldera. The summit of the 11 x 15 km island rises about 3,000 m from the sea floor between Bristol and Saunders Islands. Around 90% of the island is ice-covered; glaciers extending to the sea typically form vertical ice cliffs. The name Mount Belinda has been applied both to the high point at the southern end of the summit caldera and to the young central cone. Mount Oceanite, an isolated peak at the SE tip of the island, was the source of lava flows exposed at Mathias Point and Allen Point. There was no record of Holocene activity until MODIS satellite data, beginning in late 2001, revealed thermal anomalies consistent with lava lake activity. Apparent plumes and single anomalous pixels were observed intermittently on AVHRR images from March 1995 to February 1998, possibly indicating earlier volcanic activity.

Sources: Hawai'i Institute of Geophysics and Planetology (HIGP) Thermal Alerts Team, British Antarctic Survey