Kelud Volcano, Java, Indonesia

The February 13, 2014, violent eruption of Kelud stratovolcano in Java, Indonesia sent volcanic ash covering an area of 70,000 square miles (181,300 square kilometers), and prompted the evacuation of tens of thousands of people. Earlier 20th century eruptions killed thousands of people, mainly as the result of hot mudflows ("lahars"). This image from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument on NASA's Terra spacecraft was acquired on February 20, after the eruption had greatly diminished. Ash-covered areas are seen on the north slopes of the volcano (the summit is hidden underneath clouds); ash-choked rivers flow down the west and southwest flanks of the volcano. ASTER's thermal infrared channels show continued activity at the summit. The image covers an area of 14.2 by 16.1 miles (23 by 26 kilometers), and is located at 7.9 degrees south, 112.3 degrees east.

Photo credit: NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team

Mount Sinabung

Mount Sinabung is a stratovolcano located in Indonesia. In late 2013, a lava dome formed on the summit. In early January 2014, the volcano erupted, and it erupted again in early February. Tall ash columns deposited material over a wide area; pyroclastic flows rumbled down the volcano's slopes, engulfing villages and resulting in fatalities.

On February 10, 2014, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument on NASA's Terra spacecraft captured an image of Sinabung: the top image depicts vegetation in red; an ash plume is light gray streaming eastward from the summit; light-colored areas on the southeast flank are pyroclastic and ash deposits. The bottom image is a composite of ASTER thermal infrared bands: the plume is in purple, indicating that its composition is mostly ash; the white triangular area is hotter than the surrounding materials; blue streaks are water clouds. The images cover an area of 10.3 by 19.6 miles (16.5 by 31.5 kilometers), and are centered at 3.2 degrees north, 98.4 degrees east.

Image credit: NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team

Jakarta, Indonesia

Jakarta is the capital and largest city of Indonesia. The population of the Jakarta conurbation is over 28 million, making it perhaps the largest metropolitan area in the world in terms of inhabitants. Established in the 4th century, it became an important trading port for the Kingdom of Sunda, and was the capital of the Dutch East Indies under the name of Batavia. The rapid growth of the city is illustrated in the three satellite images. In 1972, Landsat MSS captured an image of the city with about 11 million inhabitants. By 1994, the Landsat Thematic Mapper saw a city of 19 million. And in 2006, ASTER imaged a city of 25 million inhabitants. Each image covers an area of 40 by 50 km, and is located at 6.1 degrees south latitude, 106.8 degrees east longitude.

Image credit: NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team

Note: A rare error on the part of NASA here: They claim that the Jakarta conurbation is "perhaps the largest metropolitan area in the world in terms of inhabitants," with 28 million persons. However, the Tokyo metro area is far larger, with over 35.6 million inhabitants.

Indonesian Islands

This image from the Envisat satellite is dominated by the Indonesian islands of Bali, Lombok and Sumbawa. Bali's central mountains include peaks that reach over 3000 m, including an active volcano visible on the right side of the island. Strong reflections of the radar signal used to produce this image appear like specks of light. They are mainly detectable in the southern part of the island, and are particularly concentrated around the provincial capital city of Denpasar. This is the typical appearance of built-up areas in radar images, owing to the multiple reflection of the radar beam by buildings and especially metal constructions.

This image is a compilation of three passes by Envisat’s radar on 20 June, 19 August and 17 December 2011. Each is assigned a color (red, green and blue) and combined to produce this representation. The colors reveal changes in the surface between Envisat’s passes.

Photo credit: ESA