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Anak Krakatoa

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Anak Krakatoa
Aerial view of volcanic island with another, rocky island in the background
Anak Krakatoa in 2018
Highest point
Elevation
  • 157 m (515 ft) (current)
  • 338 m (1,109 ft) (before 2018 eruption)
ListingRing of Fire
Coordinates6°06′07″S 105°25′23″E / 6.102°S 105.423°E / -6.102; 105.423
Dimensions
Area3.22 km2 (1.24 mi2)
Naming
Native nameAnak Krakatau (Indonesian)
Geography
Anak Krakatoa is located in Indonesia
Anak Krakatoa
Anak Krakatoa
Location within Indonesia
LocationSunda Strait
Lampung, Indonesia
Geology
Rock ageHolocene – very recent
Somma-stratovolcano
Last eruptionSeptember 2026 – ongoing

Anak Krakatoa, or Anak Krakatau (Indonesian for 'child of Krakatoa'), is a volcanic island and an active volcano in Indonesia. On 29 December 1927, Anak Krakatoa first emerged from the caldera formed by the explosive volcanic 1883 eruption of Krakatoa that destroyed the island of Krakatoa (Krakatau). Sporadic eruptive activity has occurred at the site since the late 20th century. A large sector collapse of the volcano occurred on 22 December 2018, causing a deadly tsunami—the 2018 Sunda Strait tsunami. There has been subsequent activity since then in the 2020s. Anak Krakatoa's 4–6 September 2026 eruption caused a fog of ash in the nearby islands of Java, Sumatra, and other surrounding areas. Owing to its young age, the island of Anak Krakatoa is one of several in the area which are of interest to, and the subject of extensive study by, volcanologists.

History

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Background

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After the cataclysmic eruption of Krakatoa in 1883, Krakatoa Island lost approximately two-thirds of its mass on the northwest side, obliterating the peaks of Perboewatan 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

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In early 1927, visible volcanic activity began to occur 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] which, owing to rain and waves, once again collapsed under the sea after its volcanic activity stopped. This process reoccurred 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 ('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

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Eruptive activity, 2008

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,[note 1] and is part of the Pacific Ring of Fire.[9] The island is surrounded by three other nearby islands: Sertung Island (Verlaten Island) to the west, Krakatau Kecil Island (Lang Island, Panjang Island, or Rakata Kecil) to the east, and Rakata Island to the south; they are all in what is now the Krakatoa archipelago.

Geology

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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 less than 25 km (16 mi) thick.[9] In geological 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.[9]

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

Volcanic activity

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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.[11] On 6 May 2009, the Volcanological Survey of Indonesia raised the eruption alert status of Anak Krakatoa to Level III (Siaga; 'alert').[12] 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.[13]

2018 eruption and aftermath

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Anak Krakatoa over time (post-1927), ending right before the 2018 eruption

A new eruptive phase was observed starting in June 2018; on 15 October 2018, Anak Krakatoa had a strong Strombolian to weak Vulcanian eruption that sent lava bombs into the water.[14][15]

An eruption of the volcano on 22 December 2018 caused a deadly tsunami, with waves up to five meters high making landfall.[16][17] On 31 December, the disaster agency stated the tsunami's death toll was 437, with 14,059 injured.[18] The tsunami affected more than 300 kilometers (186 mi) of coastline in Sumatra and Java, and 40,000 people were displaced.[19] This made the eruption the second deadliest volcanic eruption of the 21st century to date. Sector collapse—with tsunami generation—was considered a potential hazard immediately before the eruption. 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.

Starting eight hours prior to the subaerial cone collapse, it was believed that activity within the volcano produced a sustained infrasound.[20] Following the eruption, 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 the event,[22] and its elevation above sea level was reduced from 338 m (1,109 ft) to just 110 m (360 ft).[10] On 26 December, it was also reported that some of the volcanic ash fell into the western part of Java, specifically into Serang Regency and Cilegon.[23]

Modified Copernicus Sentinel-2 imagery of the volcano in February 2019

Satellite radar observations showed that by 10 January 2019, the volcano had continued to form from the continued deposition of material, with further eruptions beginning to remodel the remnant structure. The crater, which had become open to the sea immediately after the eruption, had a complete rim above sea level.[24] On 14 February 2019, the volcano erupted lightly,[25] and another eruption occurred again on 18 February whose plumes reportedly reached 610 masl.[26] On 25 March 2019, the alert status was lowered down to Level II (Waspada; 'caution') since activity 'tends to decline'.[27] 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.[28]

2020s

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

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; it 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)[note 2] magma volcanic activity report. The report also said that the first eruption lasted one minute and 12 seconds, starting at 9:58 p.m.[29] The eruption spewed ash to about 14 kilometres (46,000 ft) and a secondary ash plume made it approximately 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.[30]

21 minor eruptions occurred in early 2022;[31][32] the largest was on 24 April.[33] This led to the alert status being raised to Level III (Siaga; 'alert') on the next day.[34] A further eruption cycle began on 15 September 2023.[35][32] The PVMBG noted that they began to detect sulfur dioxide emissions via satellite data on 1 June and that shallow earthquake activity rose noticeably on 18 June 2026.[36] This was followed by an eruption in July 2026, beginning on 2 July.[37]

Satellite image of the 4–6 September 2026 eruption

The continuous eruption occurred on 4–6 September 2026.[note 3] Since then, by 06:00 a.m. on 11 September 2026, the initial eruption had been followed by a further 14 Strombolian eruptions.[38] Schools in the nearby area temporarily close in favor of remote learning. This measure was passed through Circular No. 91/SE/2026 on 5 September as a safety precaution.[39] The eruption forced the temporary closure of Soekarno–Hatta International Airport in Jakarta alongside seven other airports.[40] Initially, the volcanic ash reportedly affected 209 flights,[41] but the Indonesian Ministry of Transportation later estimated around 3,000 flights were grounded in total by 7 September, eighty percent of which were domestic flights. This affected approximately 341,000 passengers.[42] All of the airports were reopened back on 7–8 September.[43]

Based on the information collected from PVMBG, the Australian Bureau of Meteorology's Darwin Volcanic Ash Advisory Center, and analyses of Himawari 9 satellite imagery, the volcanic ashes were said to spread to five provinces via the wind: Banten, West Java, DKI Jakarta, Lampung, and Bengkulu.[44] There are two clusters of ashes; the one that is up to 20,000 feet (6,100 m) in altitude is roughly moving towards the east, and the one that is up to 50,000 feet (15,000 m) in altitude is moving west into the Indian Ocean.[45]

See also

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Notes

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  1. ↑ A UNESCO World Heritage Property.
  2. ↑ One of the Geological Agency units of Ministry of Energy and Mineral Resources (Kementerian ESDM; Kementerian Energi dan Sumber Daya Mineral).
  3. ↑ It starts from 4 September at 11:07 p.m. and ends on 6 September at 12:04 a.m. local time.

References

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  1. ↑ "7. Krakatoa, 1883: Devastation, Death, and Ecologic Revival", Volcanoes in Human History, Princeton University Press, 31 December 2002, pp. 157–185, doi:10.1515/9781400842858-011, ISBN 978-1-4008-4285-8, retrieved 6 May 2022
  2. ↑ "Krakatoa Volcano". www. volcano discovery.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 Krakatoa 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. Bibcode:2012CoMP..163..631D. doi:10.1007/s00410-011-0690-8. ISSN 1432-0967. S2CID 52064179. 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. ↑ "Pers Rilis Peningkatan Status G. Anak Krakatau Kamis 27 December 2018" [Press Releases Status Improvement of G. Anak Krakatau Thursday 27 December 2018]. MAGMA Indonesia (in Indonesian). 27 December 2018. Archived from the original on 27 December 2018. Retrieved 6 May 2022.
  9. 1 2 3 4 "Krakatoa". Global Volcanism Program. Smithsonian Institution. Retrieved 6 January 2021.
  10. 1 2 Amos, Jonathan (29 December 2018). "Indonesian volcano's lost stature". BBC News. Archived from the original on 2 February 2020. Retrieved 29 December 2018.
  11. ↑ 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.
  12. ↑ "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.
  13. ↑ 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". Geological Society, London, Special Publications. 361 (1): 79–90. Bibcode:2012GSLSP.361...79G. doi:10.1144/SP361.7. ISSN 0305-8719. S2CID 131173974. Archived from the original on 25 July 2019. Retrieved 15 January 2019.
  14. ↑ "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.
  15. ↑ Sennert, Sally Kuhn. "Report on Krakatau (Indonesia) — 20–26 June 2018". volcano.si.edu. doi:10.5479/si.GVP.WVAR20180620-262000 (inactive 11 July 2025). Archived from the original on 19 May 2021. Retrieved 4 May 2022.{{cite web}}: CS1 maint: DOI inactive as of July 2025 (link)
  16. ↑ "Indonesia tsunami: At least 222 Dead and 843 injured after Anak Krakatau volcano erupts". telegraph.co.uk. 23 December 2018. Archived from the original on 16 August 2019. Retrieved 23 December 2018.
  17. ↑ Amos, Jonathan (29 December 2018). "Anak Krakatau: Indonesian Volcano's Dramatic Collapse". BBC News. Archived from the original on 2 February 2020. Retrieved 4 May 2022.
  18. ↑ "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.
  19. ↑ "Volcano that triggered tsunami now a quarter of its pre-eruption size". NBC News. Associated Press. 29 December 2022. Archived from the original on 12 October 2019. Retrieved 4 May 2022.
  20. ↑ "Reconstruction of the 2018 tsunamigenic flank collapse and eruptive activity at Anak Krakatau based on eyewitness reports, seismo-acoustic and satellite observations". Earth and Planetary Science Letters. 541. 1 July 2020. doi:10.1016/j.ep. ISSN 0012-821X. Archived from the original on 6 May 2023.
  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. Bibcode:2019NatCo..10.4339W. doi:10.1038/s41467-019-12284-5. ISSN 2041-1723. PMC 6773710. PMID 31575866.
  23. ↑ "Status Gunung Anak Krakatau Naik dari Waspada (Level II) ke Siaga (Level III), Warga Diimbau Jauhi Radius 5 km dari Kawah" [Mount Anak Krakatau's status has been raised from Advisory (Level II) to Watch (Level III); residents are urged to stay away from a 5-km radius around the crater.]. ESDM. 27 December 2018. Retrieved 9 September 2026.
  24. ↑ 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.
  25. ↑ "Informasi Erupsi G. Anak Krakatau" [Information on the Eruption of Mt. Anak Krakatau]. ESDM. 14 February 2019. Archived from the original on 23 February 2019. Retrieved 11 September 2026.
  26. ↑ "Erupsi Gunung Anak Krakatau, Zona Aman di Luar Radius 5 Km dari Kawah" [Mount Anak Krakatau Eruption, Safe Zone Beyond 5 Km Radius from Crater]. ESDM (in Indonesian). 18 February 2019. Retrieved 11 September 2026.
  27. ↑ Arvirianty, Anastasia (25 March 2019). "Status Anak Gunung Krakatau Turun Jadi Waspada" [Anak Krakatau's Status Downgraded to Caution]. CNBC Indonesia (in Indonesian). Retrieved 12 September 2026.
  28. ↑ "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.
  29. ↑ 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.
  30. ↑ Dan Satherley (11 April 2020). "Eruption at Indonesian volcano Krakatoa". Newshub. Archived from the original on 11 April 2020. Retrieved 11 April 2020.
  31. ↑ "Indonesia's Anak Krakatau 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.
  32. 1 2 "Laporan Aktivitas Gunung Api" [Volcanic Activity Report]. Magma Indonesia (in Indonesian). Volcanological Survey of Indonesia. 20 December 2025. Retrieved 20 December 2025.
  33. ↑ "Anak Krakatau volcano erupts, spews huge ash tower". The Jakarta Post. Archived from the original on 27 April 2022. Retrieved 27 April 2022.
  34. ↑ "Badan Geologi Kementerian ESDM Naikkan Status Gunung Anak Krakatau Menjadi Level III" [The Geological Agency of the Ministry of Energy and Mineral Resources raised the status of Mount Anak Krakatau to Level III.]. ESDM (in Indonesian). 25 April 2022. Retrieved 12 September 2026.
  35. ↑ "Overall Green alert Volcanic eruption for Krakatau". Global Disaster Alert and Coordination System. 27 November 2023. Retrieved 28 November 2023.
  36. ↑ "Volcanic Activity Report on Krakatau (Indonesia) — 18 June-24 June 2026". Smithsonian Institution and US Geological Survey. Retrieved 12 September 2026.
  37. ↑ Smithsonian Global Volcanism Program, Volcanic Activity Report on Krakatau (Indonesia), 2 July 2026-8 July 2026, Retrieved 15 July 2026.
  38. ↑ "Perkembangan Erupsi Gunungapi Anak Krakatau Tanggal 11 September 2026" [Eruption Developments at Anak Krakatau Volcano on 11 September 2026]. ESDM. 11 September 2026. Retrieved 12 September 2026.
  39. ↑ "Jakarta Orders Remote Learning as Anak Krakatau Ash Threatens Air Quality". Jakarta Globe. Retrieved 8 September 2026.
  40. ↑ All of the eight airports that have been closed were: Soekarno–Hatta International Airport, Halim Perdanakusuma International Airport, Radin Inten II International Airport, Husein Sastranegara Airport, Budiarto Airport, Pondok Cabe Airport, Taufiq Kiemas Airport, and Atung Bungsu Airport. Johnson, Tamika (7 September 2026). "Anak Krakatau Eruption Closes Eight Indonesian Airports". MiGFlug. Retrieved 13 September 2026.
  41. ↑ "Indonesia's volcanic eruption halts flights, schools, fishing". CNN. 6 September 2026. Retrieved 6 September 2026.
  42. ↑ "Krakatau Disruption Could Cost Airlines Up to Rp19 Billion Daily: INACA". Migrant Times. 8 September 2026. Retrieved 10 September 2026.
  43. ↑ Cushing, Christopher; Mair, John; Feast, Lincoln; Lewis, Barbara, eds. (8 September 2026). "Indonesia reopens all airports as Anak Krakatau ash clears". Reuters. Reporting by Stanley Widianto, Yuddy Cahya Budiman, Stefanno Sulaiman, and Ananda Teresia. Retrieved 12 September 2026.
  44. ↑ Rahmawati, Dwi. "Badan Geologi Ungkap Abu Vulkanik Anak Krakatau Menyebar ke 5 Provinsi" [Geological Agency Reveals Anak Krakatau Volcanic Ash Spreads to 5 Provinces]. detiknews (in Indonesian). Retrieved 6 September 2026.
  45. ↑ Herlambang, Dwi (6 September 2026). "BMKG Terus Pantau Dampak Erupsi Gunung Anak Krakatau" [BMKG Continues to Monitor the Impact of the Anak Krakatau Eruption]. Badan Meteorologi, Klimatologi, dan Geofisika (in Indonesian). Retrieved 8 September 2026.
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