Review of morphological changes of Anak Krakatau before and after 2018 eruption using Aerial photogrammetry

Abstract We carried out drones photogrammetry on Anak Krakatau in 2013, 2019, 2020 and 2021. Changes in the morphology of Anak Krakatau occurred so quickly as its volcanic activity never stopped. Its pyroclastic cone in 2013 reached a height of 334 meters with a coastline circumference of 6.8 km. The circumference of the pyroclastic cone calculated from the traces of the old crater wall has a volume of 31971 m3. During the 2018 eruption, a large part of the cone was pulverised, resulting in a large crater of 400 m in diameter. Paradoxically, while the top of the volcano has dropped to 156 m, the island-volcano has grown relatively large, with an additional circumference of 7.2 km. The body of Anak Karakatu has experienced an addition to the coastline, especially on the South, East and North sides. This happened due to the eruption and tsunami accompanied by avalanches during the December 2018 eruption. During the 2020 and 2021 eruption periods, the coastline has not changed. This period was marked by the growth of a pyroclastic cone in the crater that had formed previously during the 2019 eruption. The pyroclastic cone was opened to the southwest by lava flows that flowed westward as far as 600 meters.