This pair of images provided by the Geospatial Information Authority of Japan (GSI) and dated Aug. 20 and Dec. 24, 2018, respectively, shows the collapse of nearly half of the approximately 2-kilometer-square volcanic island of Anak Krakatau in Indonesia. An eruption of the volcano triggered a deadly tsunami that struck coastal areas along the country's Sunda Strait on Dec. 22. At the request of the GSI, Japan Aerospace Exploration Agency (JAXA) conducted satellite observations of the areas around the island, and the GSI analyzed the collected data by comparing the images captured before and after the eruption. The GSI believes that the collapse of a chunk of the mountain, including the 200- to 300-meter-diameter crater, was caused by the eruption. The tsunami was apparently triggered by a large amount of earth sliding into the ocean due to the collapse.
(Japanese original by Tomohiro Ikeda, Science & Environment News Department)