A Bright Spot at Mount Michael

Winter near the Antarctic Circle brings months of frozen darkness, when sea ice chokes ocean waters and many of its denizens hunker down to ride out the harsh conditions. But as winter began to release its icy grip, an uncommonly clear satellite image revealed that part of this remote realm was still very much awake, at least volcanically speaking.

Mount Michael, the stratovolcano at the center of Saunders Island, rises above the ice-filled South Atlantic Ocean in this image, acquired with the OLI (Operational Land Imager) on the NASA-USGS Landsat 8 satellite on August 24, 2026. The natural-color image is overlaid with an infrared signal (OLI bands 7-6-5), shown in red, revealing heat from the persistent lava lake in its summit crater. A puff of a volcanic plume hovering over the peak, along with darkened snow on its northern slopes, also suggests ongoing activity.

Saunders Island is one of the South Sandwich Islands, a string of small volcanic peaks about 350 kilometers (220 miles) long that formed from the South American plate subducting beneath the tiny South Sandwich plate. Regular eruptions, including at Mount Michael, have occurred on these islands in recent centuries.

Because of the volcanoes’ remoteness, scientists rely on satellite data to understand their activity. An analysis of thermal anomalies in Landsat, Sentinel, and ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) observations spanning 30 years led researchers to conclude that Mount Michael hosts a persistent lava lake in its summit crater. Only a handful of other volcanoes on Earth, including Kīlauea, Nyamulagira, and Erta Ale, are known to have similar, frequently active features.

Thermal observations from the MODIS (Moderate Resolution Imaging Spectroradiometer) and VIIRS (Visible Infrared Imaging Radiometer Suite) instruments have also enabled long-term monitoring of Mount Michael. Data provided through MIROVA, a near-real-time volcanic hot spot detection system, indicate that low-intensity activity has been ongoing at the volcano for the past several years. Other observations from NASA's Aura satellite show that emissions of sulfur dioxide and other gases are common at Mount Michael.

The cloud-free window over Mount Michael would close in short order. One week later, when Landsat 9 passed over the island, a more active atmosphere had returned. But the weather patterns interacted with the island to put on a spectacle of their own. The 843-meter-high (2,766-foot-high) peak jutting from the ocean disturbed passing winds to produce a series of wave clouds resembling the wake of a ship, a familiar phenomenon in this region. False-color imagery captured by NASA’s Aqua satellite indicates that a volcanic track caused by degassing sulfur dioxide was likely present as well.

NASA Earth Observatory images by Michala Garrison, using Landsat data from the U.S. Geological Survey. Story by Lindsey Doermann.

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Full text from nasa.gov (public domain).