
The 2018 Sunda Strait Tsunami was a major tsunami which struck the Sunda Strait between the islands of Java and Sumatra in Indonesia on the 22nd of December 2018. The tsunami was caused by volcanic activity at the site of Anak Krakatoa, a volcanic island which emerged in the region back in 1927 from the caldera formed by the famous explosion of Krakatoa in 1883. Volcanic activity at Anak Krakatoa caused a landslide which in turn caused the tsunami. It impacted most severely on the Banten region at the western end of the island of Java and the Lampung district of southern Sumatra. At least 426 people were killed as waves up to thirteen meters high struck the coastal regions. Over 14,000 people suffered injuries and thousands of homes and businesses were damaged or destroyed. Owing to the damage incurred, tens of thousands of people were temporarily displaced and the tsunami led to some migration and demographic impacts.[1]
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Sunda Strait Tsunami chronology of events

The Sunda Strait Tsunami disaster has its roots all the way back in 1883 when the volcano on the island of Krakatoa in the Sunda Strait region erupted in one of the most destructive volcanic eruptions in human history. The noise from the explosion was heard 3,000 kilometers away in Australia and it completely destroyed the island of Krakatoa. The volcanic winter that ensued from the release of 20 million tons of sulfur into the earth’s atmosphere lowered world temperatures by over half a degree Celsius. It claimed 36,000 lives as well.[2] Nearly half a century later, in 1927, a new island began to emerge out of the sea as part of the caldera of Krakatoa, the large cauldron-like formed from the magma after it cooled and hardened. By 1930 it had formed into a clearly visible island. As volcanic activity continued here the island, named Anak Krakatoa, ‘Child of Krakatao’, grew larger over time.[3]
The tsunami in 2018 was caused by Anak Krakatoa. Volcanic activity has continued sporadically here over the twentieth and early twenty-first century. On the 22nd of December 2018, a particularly violent bit of seismic activity led to the volcanic caldera largely collapsing on Anak Krakatoa. Prior to this it had risen to be over 325 meters high, but the eruption led to it declining to just around 110 meters. The landslide was significant and the sheer force of the caldera collapsing into the sea created the tsunami which struck the Sunda Strait.[4]

The resulting tsunami was most damaging when it made landfall around the southern shores of the island of Sumatra and the western end of the island of Java, the regions known as Lampung and Banten respectively. There are reports of the tsunami waves being as high as thirteen meters in some places where it made landfall, however the average height was around five meters, still high enough to inflict considerable damage. Well over 400 people were killed, more than 14,000 suffered injuries of varying degrees of severity, upwards of 100,000 homes were damaged and billions of dollars’ worth of damage was caused to the local economy of Banten and Lampung. Volcanic activity around Anak Krakatoa has continued ever since, with eruptions occurring most years since, albeit of a less severe kind than happened in December 2018.[5]
Extent of migration associated with the Sunda Strait Tsunami
The tsunami led to the destruction of upwards of 100,000 housing units, leaving several hundred-thousand people displaced in the immediate aftermath of it. This necessarily led to some migration as people took up temporary housing elsewhere, while others moved into the area as part of the reconstruction work. As tends to occur in such situations, some of those who left with the intention of returning once the recovery process was advanced did not do so in the end, while some of those who might have arrived to aid in the reconstruction of Banten and Lampung ended up putting down permanent roots. However, the tsunami did not lead to major migration in the way which other disasters in the region, such as the 2004 Indian Ocean Earthquake and Tsunami, did. More tangentially, the damage caused by the tsunami in 2018 badly impacted on the significant tourism industry on Java and Sumatra and this has in turn influenced migratory patterns in this part of Indonesia in the years since.[6]
Demographic impact of the tsunami
The clearest demographic impact was in the deaths of at least 426 people in the impact zone of the tsunami, tough as in all such natural or man-made disasters the exact death toll remains a point of debate, as some of those who went missing at the time and were considered casualties of the tsunami might have died from other unrelated developments. Therefore, some studies place the death toll as high as 437. Beyond this the major demographic impact in the Sunda Strait region was felt not just in the temporary loss of homes and businesses but also in the decline of tourism and other forms of economic activity in Banten and Lampung in 2019 and 2020.[7]
See also
Explore more about the 2018 Sunda Strait Tsunami
- Indonesia tsunami kills hundreds after Krakatau eruption at BBC News
- The 22 December 2018 Mount Anak Krakatau volcanogenic tsunami on Sunda Strait coasts at Copernicus.org
- Child of Krakatoa - Why the 2018 eruption caused a tsunami at The British Geological Survey
References
- ↑ https://www.nature.com/articles/s41598-019-48327-6
- ↑ https://www.nhm.ac.uk/discover/the-1883-krakatau-eruption-a-year-of-blue-moons.html
- ↑ https://earthobservatory.nasa.gov/images/5022/closeup-of-anak-krakatau
- ↑ https://www.bgs.ac.uk/news/child-of-krakatoa-why-the-2018-eruption-caused-a-tsunami/
- ↑ https://reliefweb.int/report/indonesia/indonesia-earthquakes-and-tsunami-sunda-straits-tsunami-mdrid013-epoa-update-n-15-n
- ↑ S. Sagala, et al., ‘Building Resilience from Double Disasters: The Direct Impact of the Pandeglang Tsunami 2018 and Covid-19 Outbreak on Tourism and Supporting Industry’, in IOP Conference Series: Earth and Environmental Science, Vol. 704 (2021), pp. 1–10.
- ↑ https://reliefweb.int/report/indonesia/indonesia-earthquakes-and-tsunami-sunda-straits-tsunami-mdrid013-epoa-update-n-15-n