🌋VolcanoAtlas

Krakatau

The Volcano That Changed the World

Elevation

285 m

Last Eruption

2021–2023

Type

Caldera

Country

Indonesia

Location

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Volcanic Hazards & Risk Assessment

Primary Hazards

  • Pyroclastic flows and surges
  • Large explosive eruptions (VEI 4+)
  • Ash fall and tephra deposits
  • Lahars and debris flows

Risk Level

Population at RiskHigh
Infrastructure RiskHigh
Aviation RiskSignificant

Geological Composition & Structure

Rock Types

Primary
Unknown
Silica Content
Varied composition

Tectonic Setting

Unknown
Intraplate setting with hotspot or regional volcanic activity.

Age & Formation

Epoch
Unknown
Evidence
Unknown

Eruption Statistics & Analysis

MetricValueGlobal RankingSignificance
Total Recorded EruptionsUnknownLowModerately active volcano
Maximum VEIVEI UnknownMinorLocal impact potential
Recent Activity-20209997 years agoVery RecentCurrently active

Monitoring & Alert Status

Monitoring Networks

Global Volcanism Program
International eruption database

Current Status

Active
Recent volcanic activity detected. Continuous monitoring in place.

Authority Sources

Smithsonian GVP
Official volcano database

Related Volcanoes

All Indonesia Volcanoes
Explore by country
Caldera Volcanoes
By volcano type
Sunda Strait, between Java and Sumatra
Regional volcanoes

Other Volcanoes in Indonesia

Interesting Facts

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The 1883 eruption of Krakatau produced the loudest sound in recorded history — the final explosion was heard 4,800 km away on Rodrigues Island near Mauritius, and the sound wave traveled around the globe three and a half times.

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Tsunamis generated by the 1883 eruption reached heights of up to 46 m (151 ft) at Merak on the Java coast — taller than a 15-story building.

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The atmospheric pressure wave from the 1883 eruption was recorded on barographs worldwide, with measurable fluctuations continuing for five days as the wave circled the Earth repeatedly.

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The volcanic aerosols from 1883 produced such vivid red sunsets that fire brigades were called out in New York and other cities by citizens who believed massive fires were burning on the horizon.

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Anak Krakatau first emerged above sea level in 1927, just 44 years after the eruption that destroyed its parent — growing at an average rate of approximately 5 m per year.

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The 2018 flank collapse of Anak Krakatau occurred without significant seismic warning, generating a tsunami that arrived at the Java coast in just 24 minutes.

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Krakatau has erupted 58 times in its recorded history, with 44 eruptions occurring since Anak Krakatau emerged in 1927 — roughly one eruption every two years.

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The 1883 eruption ejected approximately 25 km³ of rock and ash — enough to bury Manhattan under a layer approximately 37 m (120 ft) deep.

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Pyroclastic surges from the 1883 eruption traveled 40 km across the open surface of the Sunda Strait to reach the coast of Sumatra — an extraordinary distance for a volcanic density current.

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The common English spelling 'Krakatoa' originated from a telegraph transmission error in 1883 — the correct Indonesian name is 'Krakatau.'

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The 1883 eruption lowered global temperatures by approximately 1.2°C for five years and produced vivid sunsets worldwide that are believed to have inspired Edvard Munch's 'The Scream.'

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Rakata Island, the surviving remnant of the pre-1883 volcano, has been the subject of landmark ecological studies on how life recolonizes devastated volcanic islands — informing island biogeography theory.

Frequently Asked Questions

Is Krakatau still active?
Yes, Krakatau is one of the most active volcanoes in Indonesia. The current active center is Anak Krakatau ('Child of Krakatau'), a cone that emerged from the sea in 1927 within the caldera created by the catastrophic 1883 eruption. Anak Krakatau has erupted 44 times since its emergence — an average of roughly one eruption every two years. The most recent eruption occurred from 2021 to 2023, producing Strombolian explosions and ash emissions. The volcano is continuously monitored by Indonesia's PVMBG (Center for Volcanology and Geological Hazard Mitigation) using seismometers, satellite imagery, and visual observation. Future eruptions are considered virtually certain, and a 2-km exclusion zone around the island is frequently enforced.
When did Krakatau last erupt?
Krakatau's most recent eruption occurred from May 2021 to 2023 at Anak Krakatau, producing Strombolian explosions, ash columns, and incandescent lava fragments (VEI 2). Prior to this, the most significant recent event was the 2018–2020 eruption sequence (VEI 3), which culminated in the catastrophic flank collapse of December 22, 2018 that triggered a deadly tsunami killing 437 people. Krakatau's most famous eruption remains the VEI 6 cataclysm of August 26–27, 1883, which killed more than 36,000 people and produced the loudest sound in recorded history. With 58 recorded eruptions, Krakatau is one of the most prolific erupters among Indonesian volcanoes.
Could Krakatau erupt again like 1883?
While another eruption on the scale of 1883 (VEI 6) is theoretically possible, it is considered unlikely in the near term because such an event would require the accumulation of a very large volume of evolved, silica-rich magma — a process that takes centuries to millennia. Anak Krakatau's current eruptions are much smaller (VEI 1–3), producing basaltic andesite magma rather than the dacite that fueled the 1883 paroxysm. However, the more immediate concern is the potential for further flank collapses generating tsunamis — the 2018 event demonstrated that even relatively small collapses at Krakatau can be deadly due to the volcano's island location in a populated strait. Krakatau's geological record shows multiple caldera-forming eruptions, confirming that cataclysmic events are part of the volcano's long-term behavior cycle.
How many people died in the 1883 Krakatau eruption?
The official death toll from the 1883 eruption is 36,417, though some estimates range as high as 120,000. The vast majority of fatalities were caused by tsunamis generated by pyroclastic flows entering the sea and caldera collapse, rather than direct volcanic effects. Waves reaching 30–46 m in height devastated the coastlines of western Java and southern Sumatra. The town of Merak was completely destroyed. An additional estimated 1,000 people on the coast of Sumatra were killed by pyroclastic surges that traveled 40 km across the surface of the Sunda Strait. The 1883 Krakatau eruption ranks as one of the deadliest volcanic events in recorded history.
What was the loudest sound in history?
The eruption of Krakatau at approximately 10:02 AM local time on August 27, 1883 produced what is considered the loudest sound in recorded history. The explosion was heard clearly 4,800 km away on Rodrigues Island near Mauritius in the Indian Ocean — equivalent to hearing a sound from London in New York. Closer to the volcano, the sound ruptured the eardrums of sailors 64 km away. The atmospheric pressure wave generated by the explosion was recorded on barographs at meteorological stations worldwide and circled the globe three and a half times over the following five days. The sound has been estimated at approximately 310 decibels at the source.
What is Anak Krakatau?
Anak Krakatau (Indonesian for 'Child of Krakatau') is a volcanic island that emerged from the sea on December 29, 1927 within the caldera created by the catastrophic 1883 eruption of Krakatau. The cone grew rapidly through nearly continuous eruptive activity, reaching 338 m in height and approximately 2 km in diameter by 2018. On December 22, 2018, the southwest flank collapsed into the sea, triggering a tsunami that killed 437 people and reducing the cone's height to approximately 110 m. Since then, renewed eruptions have partially rebuilt the cone to approximately 285 m (as of 2023). Anak Krakatau is one of the most active volcanoes in Indonesia, with 44 eruptions recorded since its emergence.
Is it Krakatoa or Krakatau?
The correct name is Krakatau, which is the Indonesian spelling used by the Smithsonian Global Volcanism Program, Indonesian authorities, and most volcanologists. The English spelling 'Krakatoa' originated from a telegraph transmission error when news of the 1883 eruption was communicated globally via undersea cable. The garbled version became fixed in English-language newspapers and was subsequently popularized through books and films, including the 1969 movie 'Krakatoa: East of Java' (which also got the geography wrong — Krakatau lies west of Java). While 'Krakatoa' remains common in English popular culture, 'Krakatau' is the scientifically and linguistically correct form.
Can you visit Krakatau?
Krakatau can be visited by boat from the western Java coast, with departures typically from Carita Beach or Anyer in Banten province (about 3 hours from Jakarta by road, then 1.5–3 hours by boat). Tours usually visit Rakata Island and the older caldera rim islands, with views of Anak Krakatau from a distance. However, landing on Anak Krakatau has been restricted since the 2018 flank collapse, with a 2-km exclusion zone enforced during periods of elevated activity. The surrounding waters offer excellent snorkeling and diving. Tours should be arranged through reputable operators with proper safety equipment. The best time to visit is during the dry season (May–September) when seas are calmer.
What caused the 2018 Krakatau tsunami?
The December 22, 2018 tsunami was caused by the collapse of approximately two-thirds of Anak Krakatau's above-sea-level volume into the sea. An estimated 150–180 million cubic meters of volcanic material slid from the southwest flank during an ongoing eruption, displacing a massive volume of water that generated tsunami waves of up to 5 m striking the coasts of Banten (Java) and Lampung (Sumatra). The collapse occurred at approximately 9:03 PM local time with virtually no seismic warning, and waves reached the nearest coastlines within 24 minutes. The event killed 437 people, injured over 14,000, and displaced more than 33,000. It exposed critical gaps in Indonesia's tsunami warning system, which had been designed for earthquake-generated tsunamis.
How big was the 1883 Krakatau eruption?
The 1883 eruption was rated VEI 6 on the Volcanic Explosivity Index, making it one of the most powerful eruptions in recorded history. It ejected approximately 25 km³ of rock and ash (12 km³ dense rock equivalent), destroyed two-thirds of the volcanic island through caldera collapse, and generated an eruption column reaching approximately 80 km into the atmosphere. The eruption was approximately ten times more powerful than the 1980 Mount St. Helens eruption (VEI 5) but about fifty times less powerful than the 1815 Tambora eruption (VEI 7). The energy released has been estimated at approximately 200 megatons of TNT — roughly four times the yield of the largest nuclear weapon ever detonated (Tsar Bomba, 50 megatons).