Anak Krakatoa

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Anak Krakatoa
AnukKrakatau-volcanological-survey-of-Indonesia-1979.jpg
Aerial view of Anak Krakatau looking south-southeast toward Rakata island, circa 1979
Highest point
Elevation
  • 155 m (509 ft) (current)
  • 338 m (1,109 ft) (before 2018 eruption)
ListingSpesial Ribu
Coordinates6°06′07″S 105°25′23″E / 6.102°S 105.423°E / -6.102; 105.423Coordinates: 6°06′07″S 105°25′23″E / 6.102°S 105.423°E / -6.102; 105.423
Naming
Native nameAnak Krakatau  (Indonesian)
Geography
Anak Krakatoa is located in Indonesia
Anak Krakatoa
Anak Krakatoa
Location
LocationSunda Strait, Indonesia
Geology
Age of rockHolocene – very recent
Mountain typeSomma-stratovolcano
Last eruption24 April 2022 (Ongoing)

Anak Krakatoa (Indonesian: Anak Krakatau)[notes 1] is a volcanic island in Indonesia. On 29 December 1927, Anak Krakatoa first emerged from the caldera formed in 1883 by the explosive volcanic eruption that destroyed the island of Krakatoa. There has been sporadic eruptive activity at the site since the late 20th century, culminating with a large underwater collapse of the volcano that caused a deadly tsunami in December 2018. There has been subsequent activity since. Due to its young age, the island is one of several in the area that are of interest to, and the subject of extensive study by, volcanologists.

History[edit]

Background[edit]

After the cataclysmic eruption of Krakatoa in 1883, Krakatoa Island lost approximately two-thirds of its body on the northwest side, obliterating the peaks of Perbuwatan and Danan, and leaving only the southern half of the island, including the Rakata volcano, as the last remnant of the original island. The lost area became a shallow sea.[1]

Regrowth[edit]

In early 1927 volcanic activity began to appear at the point located between where the former peaks of Mount Perboewatan and Mount Danan had been.[2] This was a short-lived appearance of a small island that was sunk by sea waves within a week.[3] Several months later, volcanic activity began to create a more permanent land formation[4] that, due to rain and waves, once again collapsed under the sea after its volcanic activity stopped. This process repeated several times during the next three years. On 11 August 1930, the volcanic island permanently rose above sea level, and was locally named Anak Krakatau (or "Child of Krakatoa").[5] It has been the site of repeated eruptive episodes ever since.[6][7] Anak Krakatoa's highest point increased at an average rate of 7–9 meters per year through September 2018.[8]

Geography[edit]

Anak Krakatoa is located in the Sunda Strait—between the islands of Java and Sumatra—in the Indonesian province of Lampung.[9] The volcano is contained within the Ujung Kulon National Park,[notes 2] and is part of the Pacific Ring of Fire.[10]

Geology[edit]

Eruptive activity, 2008

The island is situated approximately 700 km (430 mi) north of the Sunda Trench marking the subduction zone separating the Australian Plate and the fixed Sunda Plate, atop an oceanic crust of less than 25 km (16 mi) in thickness.[10] In geologic terms, it has recently formed within the caldera of the Krakatoa volcanic eruption. The entire island comprises a Somma-stratovolcano system of the late Holocene epoch, and features a pyroclastic cone. The major rock-type components of Anak Krakatoa include Andesite, Dacite, and Basalt; with minor indications of Trachyte.[10]

The island had reached a maximum elevation of 338 m (1,109 ft) before its collapse during the 2018 eruptive event.[11][10]

Volcanic activity[edit]

The volcano's most recent eruptive episode began in 1994. Quiet periods of a few days have alternated with almost continuous Strombolian eruptions since then. Hot gases, rocks, and lava were released in an eruption in April 2008. Scientists monitoring the volcano warned people to stay out of a 3 km (1.9 mi) zone around the island.[12]

On 6 May 2009, the Volcanological Survey of Indonesia raised the eruption alert status of Anak Krakatoa to Level 3.[13] An expedition to the volcano revealed that a 100 m (330 ft) wide lava dome was growing in its crater. In January 2012, volcanologists at the University of Oregon warned that a tsunami caused by flank collapse of Anak Krakatoa was likely, as it had formed on the steep eastern slope of the large caldera formed by the 1883 explosive eruption.[14]

2018 eruption and aftermath[edit]

A new eruptive phase was observed starting in June 2018; and on 15 October 2018, Anak Krakatau had a strong Strombolian to weak Vulcanian eruption that sent lava bombs into the water.[15][16]

An eruption of the volcano on 22 December 2018 caused a deadly tsunami, with waves up to five meters in height making landfall.[17][18] On 31 December 2018, the disaster agency stated the tsunami's death toll was 437, with 14,059 injured.[19] The tsunami affected more than 300 kilometers (186 mi) of coastline in Sumatra and Java and 40,000 people were displaced.[20] This made the eruption the second deadliest volcanic eruption of the 21st century to date. Cone collapse—with tsunami generation—was considered a potential hazard immediately before the eruption.[18] Scientists had modeled the possibility six years before the event, and had identified the western flank as the section of the volcano most likely to fail.[18]

Sentinel-2 satellite view of Anak Krakatoa on 3 May 2022 in natural color. Clockwise from upper left: Sertung Island; Anak Krakatoa, Panjang Island, and Rakata Island (lower right).

Following the December 2018 eruption, it was believed that the southwest sector of the volcano, including the summit, had collapsed during the eruption, triggering the tsunami. On 23 December, this was confirmed by satellite data and helicopter footage, with the main conduit seen erupting from underwater, producing Surtseyan-style activity.[21] The volcano lost over two-thirds of its volume due to this event,[22] and its elevation above sea level was reduced from 338 m (1,109 ft) to just 110 m (360 ft).[11][18]

Satellite radar observations showed that by 10 January 2019, the volcano had continued to form, with further eruptions beginning to re-model the remnant structure. The crater, which had become open to the sea immediately after the eruption, had a complete rim above sea level.[23] In May 2019, phreatomagmatic activity was observed around the newly reconstructed crater as the volcano continued to increase in height and remodel the areas destroyed in 2018.[24]

2020 eruption[edit]

Anak Krakatoa began erupting again on the morning of 10 April 2020. The first eruption could be heard in the Indonesian capital of Jakarta, over 150 kilometres (93 mi) away, and was spewing out a 200 metres (660 ft) high column of ash and smoke according to the Center for Volcanology and Geological Disaster Mitigation's (PVMBG) magma volcanic activity report, which also said that the first eruption lasted one minute and 12 seconds starting at 9:58 p.m.[25] The eruption spewed ash to about 14 kilometres (46,000 ft) and a secondary ash plume made it to about 11 kilometres (36,000 ft). The eruption was largely magmatic with lava fountains visible. No widespread damage was reported, and the eruption ended several hours later.[26]

2022 eruption[edit]

Anak Krakatoa presented a minor eruption on 4 to 5 February 2022.[27][28] At 8:20 PM on 24 April 2022, Anak Krakatoa once again erupted, sending a massive plume of ash 3,157 metres (10,358 ft) above the sea level. The volcano had erupted 21 times in the first four months of 2022, with the 24 April eruption being the biggest.[29] On 26 April, Meteorology, Climatology, and Geophysical Agency (BMKG) increased the alert level for Anak Krakatoa from level 2 to level 3.[30] The agency warned of possible high waves and tsunami following any eruptive event.[31]

See also[edit]

Notes[edit]

  1. ^ English translation and common name: Child of Krakatoa
  2. ^ A UNESCO World Heritage Property

References[edit]

  1. ^ "7. Krakatau, 1883: Devastation, Death, and Ecologic Revival", Volcanoes in Human History, Princeton University Press, pp. 157–185, 31 December 2002, doi:10.1515/9781400842858-011, ISBN 978-1-4008-4285-8, retrieved 6 May 2022
  2. ^ "Krakatau Volcano". www.volcanodiscovery.com. Archived from the original on 28 April 2022. Retrieved 5 May 2022.
  3. ^ Mary Bagley (15 September 2017). "Krakatoa Volcano: Facts About 1883 Eruption". livescience.com. Archived from the original on 4 May 2022. Retrieved 6 May 2022.
  4. ^ Winchester, S. 2005. Krakatoa. The Day The World Exploded 27 August 1883. Penguin Books.
  5. ^ Gardner, Màiri F.; Troll, Valentin R.; Gamble, John A.; Gertisser, Ralf; Hart, Garret L.; Ellam, Rob M.; Harris, Chris; Wolff, John A. (1 January 2013). "Crustal Differentiation Processes at Krakatau Volcano, Indonesia". Journal of Petrology. 54 (1): 149–182. doi:10.1093/petrology/egs066. ISSN 0022-3530. Archived from the original on 5 January 2022. Retrieved 30 September 2020.
  6. ^ Dahren, Börje; Troll, Valentin R.; Andersson, Ulf B.; Chadwick, Jane P.; Gardner, Màiri F.; Jaxybulatov, Kairly; Koulakov, Ivan (1 April 2012). "Magma plumbing beneath Anak Krakatau volcano, Indonesia: evidence for multiple magma storage regions". Contributions to Mineralogy and Petrology. 163 (4): 631–651. doi:10.1007/s00410-011-0690-8. ISSN 1432-0967. S2CID 52064179. Archived from the original on 18 January 2022. Retrieved 4 February 2021.
  7. ^ Wild Indonesia: The Birth of an Island Archived 8 May 2021 at the Wayback Machine. PBS online books. Retrieved 27 December 2018.
  8. ^ Geologi, Pusat Vulkanologi dan Mitigasi Bencana (27 December 2018). "Pers Rilis Peningkatan Status G. Anak Krakatau Kamis 27 Desember 2018" [Press Releases Status Improvement of G. Anak Krakatau Thursday 27 December 2018]. MAGMA Indonesia (in Indonesian). Archived from the original on 27 December 2018. Retrieved 6 May 2022.
  9. ^ "Krakatoa". Global Volcanism Program. Smithsonian Institution. Retrieved 6 January 2021.
  10. ^ a b c d Global Volcanism Program; Smithsonian Institution, National Museum of Natural History – Department of Mineral Sciences ; website; accessed June 2022
  11. ^ a b Amos, Jonathan (29 December 2018). "Indonesian volcano's lost stature". BBC News. Archived from the original on 2 February 2020. Retrieved 29 December 2018.
  12. ^ Supriyatin (11 November 2007). "Indonesia's Krakatau roars, dazzles with fireworks". Reuters India. Archived from the original on 10 January 2009. Retrieved 10 January 2019.
  13. ^ "Status G. Anak Krakatau dinaikkan menjadi Siaga (Level III)" [Anak Krakatau's status raised to Alert (Level III)] (in Indonesian). Volcanological Survey of Indonesia. Archived from the original on 6 May 2009. Retrieved 20 March 2012.
  14. ^ Giachetti, T.; Paris, R.; Kelfoun, K.; Ontowirjo, B. (January 2012). Terry, J. P.; Goff, J. (eds.). "Tsunami Hazard Related to a Flank Collapse of Anak Krakatau Volcano, Sunda Strait, Indonesia". Natural Hazards in the Asia–Pacific Region: Recent Advances and Emerging Concepts. Special Publications. London: Geological Society. 361: 79–90. doi:10.1144/SP361.7. ISSN 0305-8719. S2CID 131173974. Archived from the original on 25 July 2019. Retrieved 15 January 2019.
  15. ^ "Krakatau volcano (Indonesia): vulcanian explosions - field report 13-19 Oct 2018". www.volcanodiscovery.com. Volcano Discovery. 20 October 2018. Archived from the original on 18 July 2020. Retrieved 4 May 2022.
  16. ^ Sennert, Sally Kuhn. "Global Volcanism Program | Report on Krakatau (Indonesia) — 20–26 June 2018". volcano.si.edu. doi:10.5479/si.GVP.WVAR20180620-262000 (inactive 31 July 2022). Archived from the original on 19 May 2021. Retrieved 4 May 2022.{{cite web}}: CS1 maint: DOI inactive as of July 2022 (link)
  17. ^ "Indonesia 'Volcano Tsunami': At least 168 Dead and 745 Injured after [Anak] Krakatoa Erupts". telegraph.co.uk. 23 December 2018. Archived from the original on 16 August 2019. Retrieved 23 December 2018.
  18. ^ a b c d Amos, Jonathan (29 December 2018). "Anak Krakatau: Indonesian Volcano's Dramatic Collapse". BBC News. Archived from the original on 2 February 2022. Retrieved 4 May 2022.
  19. ^ "Number of injured in Indonesia tsunami surges to over 14,000". The Star Online. Asean Plus. 31 December 2022. Archived from the original on 29 July 2019. Retrieved 31 December 2018.
  20. ^ Associated Press (29 December 2022). "Volcano that triggered tsunami now a quarter of its pre-eruption size". NBC News. Archived from the original on 12 October 2019. Retrieved 4 May 2022.
  21. ^ "22-23 Dec 2018 Eruption & Tsunami of Krakatoa - Updates". Volcano Discovery. 25 December 2018. Archived from the original on 9 June 2019. Retrieved 26 December 2018.
  22. ^ Walter, Thomas R.; Haghshenas Haghighi, Mahmud; Schneider, Felix M.; Coppola, Diego; Motagh, Mahdi; Saul, Joachim; Babeyko, Andrey; Dahm, Torsten; Troll, Valentin R.; Tilmann, Frederik; Heimann, Sebastian (1 October 2019). "Complex hazard cascade culminating in the Anak Krakatau sector collapse". Nature Communications. 10 (1): 4339. doi:10.1038/s41467-019-12284-5. ISSN 2041-1723. PMC 6773710. PMID 31575866.
  23. ^ Amos, Jonathan (10 January 2019). "Anak Krakatau: Finnish radar satellite eyes tsunami volcano". BBC News. Archived from the original on 26 May 2019. Retrieved 10 January 2019.
  24. ^ "Krakatau volcano (Indonesia) activity update and field report: increasing unrest". www.volcanodiscovery.com. Volcano Discovery. 25 May 2019. Archived from the original on 25 May 2019. Retrieved 12 June 2019.
  25. ^ Fiqih, Moch; Prawira, Adjie; Dipa, Arya (11 April 2020). "Anak Krakatau erupts, loud rumble heard in virus-stricken Greater Jakarta". The Jakarta Post. Archived from the original on 14 April 2020. Retrieved 6 January 2021.
  26. ^ Dan Satherley (11 April 2020). "Eruption at Indonesian volcano Krakatoa". Newshub. Archived from the original on 11 April 2020. Retrieved 11 April 2020.
  27. ^ "Indonesia's Anak Krakatoa Spews Ash 1,500 Metres High". South China Morning Post. 5 February 2022. Archived from the original on 5 February 2022. Retrieved 5 February 2022.
  28. ^ Indonesian Geological Agency
  29. ^ "Anak Krakatau volcano erupts, spews huge ash tower". The Jakarta Post. Archived from the original on 27 April 2022. Retrieved 27 April 2022.
  30. ^ Sennert, Sally Kuhn. "Global Volcanism Program | Report on Krakatau (Indonesia) — 20–26 April 2022". volcano.si.edu. Global Volcanism Program Smithsonian Institution. doi:10.5479/si.GVP.WVAR20220420-262000 (inactive 31 July 2022). Archived from the original on 4 May 2022. Retrieved 4 May 2022.{{cite web}}: CS1 maint: DOI inactive as of July 2022 (link)
  31. ^ "BMKG Warns of Possible Tsunami as 'Child of Krakatoa' Alert Level Raised | Coconuts". Coconuts Jakarta. 26 April 2022. Archived from the original on 27 April 2022. Retrieved 27 April 2022.

External links[edit]