According to Volcano Live, satellite imagery of Heard Island showed thermal anomalies on 21 and 24 September, and 10 and 19 October. NASA's Earth Observatory reported that a satellite image acquired on 13 October showed a possible dark area in the summit crater of Mawson Peak and hot surfaces within the crater, indicating the presence of lava in or just beneath the crater.

Geological Summary. Heard Island on the Kerguelen Plateau in the southern Indian Ocean consists primarily of the emergent portion of two volcanic structures. The large glacier-covered composite basaltic-to-trachytic cone of Big Ben comprises most of the island, and the smaller Mt. Dixon lies at the NW tip of the island across a narrow isthmus. Little is known about the structure of Big Ben because of its extensive ice cover. The active Mawson Peak forms the island's high point and lies within a 5-6 km wide caldera breached to the SW side of Big Ben. Small satellitic scoria cones are mostly located on the northern coast. Several subglacial eruptions have been reported at this isolated volcano, but observations are infrequent and additional activity may have occurred.

Sources: Volcano Live, NASA Earth Observatory