Tofua Island, Tonga Islands

Tofua Island in the central part of the Tonga Islands group is the summit of a large stratovolcano that contains a 5-km-wide caldera. Three post-caldera cones were constructed at the northern end of a caldera lake. The easternmost cone produced lava flows, some of which have traveled into the caldera lake. The current eruption period began in October 2015 and has more recently consisted of thermal activity. The image was acquired October 10, 2023, covers an area of 11.6 by 12 km, and is located at 19.7 degrees south, 175.1 degrees west.

With its 14 spectral bands from the visible to the thermal infrared wavelength region and its high spatial resolution of about 50 to 300 feet (15 to 90 meters), ASTER images Earth to map and monitor the changing surface of our planet. ASTER is one of five Earth-observing instruments launched Dec. 18, 1999, on Terra. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and data products.

The broad spectral coverage and high spectral resolution of ASTER provides scientists in numerous disciplines with critical information for surface mapping and monitoring of dynamic conditions and temporal change. Example applications are monitoring glacial advances and retreats; monitoring potentially active volcanoes; identifying crop stress; determining cloud morphology and physical properties; wetlands evaluation; thermal pollution monitoring; coral reef degradation; surface temperature mapping of soils and geology; and measuring surface heat balance.

The U.S. science team is located at NASA's Jet Propulsion Laboratory in Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate, Washington.

More information about ASTER is available at http://asterweb.jpl.nasa.gov/.