In the image of Saunders Island, thermal anomalies are present inside the summit craters of Mount Michael but nothing unusual shows up in the natural colour image suggesting that it may be no more than elevated ground temperatures inside the craters with slight fumarolic activity at best.
Nothing unusual also shows up in the natural colour image of Zavodovski Island but however, a strong thermal anomaly was present around the crater area of Mount Curry which suggests that it's more likely to be intensive fumarolic activity although I personally wouldn't rule out a small possibility of it being pyroclastic deposits.
|Heat sources in the craters of Mount Michael. SOURCE: Landsat 8/USGS/NASA.|
|Strong heat source present on the west side of Mount Curry. SOURCE: Landsat 8/USGS/NASA.|