Kīlauea, a shield volcano located on the southeastern shore of Hawaii Island, is one of the most active volcanoes on Earth. Its name, meaning “spewing” or “much spreading” in Hawaiian, reflects its frequent outpouring of lava. This volcano is a central feature of Hawaii Volcanoes National Park and a major tourist destination. Kīlauea is the second youngest volcano in the Hawaiian-Emperor seamount chain and has been growing above sea level for about 100,000 years.

Kīlauea Volcano

Geological Structure Kīlauea’s structure includes a summit caldera called Kaluapele, which measures approximately 4 by 3.2 km. Within the caldera lies Halemaʻumaʻu, a historically active pit crater. The volcano also has two active rift zones extending east and southwest. The eastern rift zone is the most active, characterized by low-lying ridges and pit craters. The Hilina fault system is another prominent structure, causing the volcano’s southern flank to slowly slide seaward.

Eruptive History Kīlauea’s eruptions have varied greatly in duration and intensity.

  • Prehistoric Eruptions: The oldest lava flows, dating back 275,000 to 225,000 years, were discovered on the submerged southern slope. The Uwēkahuna Ash Member, dating from 800 to 100 BC, indicates a period of powerful explosive eruptions from the Powers Caldera.
  • 1410 to 1790: The ʻAilāʻau eruption lasted approximately 60 years, covering much of Kīlauea and leading to the formation of Kaluapele. This was followed by a 300-year period of explosive eruptions.
  • 1790 to 1934: A phreatomagmatic eruption in 1790 caused the death of over 400 people, making it the deadliest volcanic eruption in what is now the United States. The first well-documented eruption by Westerners occurred in 1823. Activity was nearly continuous at Kaluapele for much of the 19th century. In 1840, a major effusive eruption occurred on the eastern rift zone. The 1924 eruption involved explosive activity, including a major blast on May 18 which resulted in one fatality.
  • 1952 to 1982: After a period of quiet, Kīlauea reactivated with a lava fountain in Halemaʻumaʻu in 1952. The 1960 eruption involved a massive ʻaʻā flow that overran communities. The Mauna Ulu eruption from 1969 to 1974 was the longest flank eruption recorded at the time.
  • 1983 to 2018: This period saw the longest-duration eruption in modern times, originating from the eastern rift zone. The eruption formed the Puʻu ʻŌʻō cone and later shifted to Kūpaʻianahā, causing significant property damage and destroying towns and beaches. A separate eruption began at Kilauea’s summit in 2008, creating the “Overlook Crater” within Halemaʻumaʻu. The lava lake within the Overlook Crater was active until 2018. In 2018, activity shifted to the lower Puna district, creating numerous fissures and destroying several communities.
  • 2019–2024: A water lake appeared at the bottom of Halemaʻumaʻu in 2019. The summit eruption in December 2020 replaced the water lake with a lava lake. Further eruptions occurred in September 2021, and in January, June and September 2023. In 2024, eruptions occurred in the upper southwest rift zone in June, in the middle east rift zone in September, and inside Halemaʻumaʻu in December.

Hazards and Impact Kīlauea is considered the most threatening volcano in the United States due to its likelihood of affecting lives and infrastructure. Its eruptions, although often effusive, can also be explosive. The 1790 eruption had a Volcanic Explosivity Index (VEI) of 4, while the 1983-2018 eruption was a 3. The volcano’s activity has a significant impact on its surrounding environment, damaging vegetation and impacting the local climate. However, the island’s isolation has also allowed highly endemic wildlife to flourish.

Human Interaction Kīlauea is considered sacred by native Hawaiians, with Halemaʻumaʻu believed to be the home of Pele, the goddess of fire. The Hawaiian Volcano Observatory, founded in 1912, has served as the main research body on the volcano. The area around Kīlauea is a major tourist attraction, drawing millions of visitors annually.

Kīlauea continues to be a dynamic and fascinating geological wonder, demonstrating the ongoing forces that shape our planet.

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