Kilauea

Kilauea is a shield volcano on the Big Island of Hawaii and one of the most active volcanoes on Earth. Unlike the explosive stratovolcanoes of Indonesia or Italy, Kilauea typically produces gentle, flowing eruptions of runny basalt lava. The lava can be safely watched from a distance and has become one of the world's top tourist attractions. The volcano was almost continuously erupting from 1983 to 2018 (the longest eruption in recorded history) and has had several major eruptions since. In Hawaiian culture, Kilauea is the home of Pele, the volcano goddess.

• TypeShield volcanoWide and gently sloping
• Height1,247 mPlus a much taller base under the sea
• LocationBig Island, Hawaii
• Longest eruption35 years (1983 to 2018)Longest in recorded history
• Lava typeBasaltRunny, hot (1,150 degrees C+), low-silica
• In Hawaiian mythHome of PeleGoddess of volcanoes and fire

The 1983 to 2018 eruption

Kilauea's east rift zone began erupting on 3 January 1983 and continued, almost without a pause, for the next 35 years: the longest continuous volcanic eruption in modern human history. During this time, lava destroyed approximately 250 homes, added 1.6 square kilometres of new land to the Hawaiian shoreline, and created one of the world's most spectacular natural displays as glowing lava poured into the Pacific Ocean.

The eruption ended dramatically in April-May 2018 with a massive draining of the summit lava lake and a series of new fissure eruptions that destroyed approximately 700 homes in the Leilani Estates and Kapoho areas. After all this, Kilauea finally went quiet for a few months. It started erupting again at the summit in December 2020 and has been intermittently active ever since.

Why Kilauea's lava behaves differently

Kilauea sits over a hot spot: a deep plume of unusually hot mantle rock rising from far beneath the Pacific Plate. The hot spot produces large volumes of basalt magma that is hot (1,150+ degrees C), runny and relatively low in dissolved gas.

This is why Kilauea's eruptions are so different from those of explosive subduction-zone volcanoes:

• The runny lava flows easily, sometimes for tens of kilometres.
• The dissolved gases can escape gently, so eruptions are rarely explosive.
• Repeated lava flows build wide, gently sloping shield-shaped volcanoes, very different from the steep cones of stratovolcanoes.
• Tourists can safely watch active eruptions from a reasonable distance.

Two famous lava forms

Hawaiian basalt lava cools into two characteristic textures.

• Pahoehoe (pronounced "pa-HOY-hoy"): smooth, ropy or pillow-shaped surfaces. Forms from quickly flowing, hot, low-viscosity lava.
• A'a (pronounced "ah-AH"): rough, jagged, clinkery surfaces that crunch underfoot. Forms from cooler, slower-moving lava with a slightly different mix of gas and crystals.

Both Hawaiian terms have been adopted internationally by volcanologists.

Fact During the 1983 to 2018 eruption, Kilauea added approximately 1.6 square kilometres of brand new land to Hawaii by pouring lava into the ocean and creating new shoreline. Visitors could watch glowing red lava cascade into the sea, producing huge clouds of steam. The new land is unstable for many years afterwards (it sometimes collapses back into the sea in chunks called "bench collapses") but eventually becomes solid Hawaiian coastline.

Pele, the volcano goddess

In traditional Hawaiian belief, Kilauea is the home of Pele, the goddess of volcanoes, fire and lightning. According to legend, Pele lives in the active Halema'uma'u Crater at the summit of Kilauea. The shapes of cooling lava are sometimes called Pele's hair (long fine glass threads spun out by lava fountains in the wind) and Pele's tears (small droplets of lava that solidify in mid-flight).

Many Hawaiians still leave offerings of flowers, food or coins at the volcano's edge in honour of Pele. There is also an old (and probably apocryphal) curse called the Curse of Pele, which is said to bring bad luck to anyone who takes lava rock or sand from the island as a souvenir. Hawaii's national parks receive hundreds of mailed packages every year from tourists returning rocks they had taken, often with apologetic letters describing the bad luck they have suffered.

Did you know? Kilauea's summit is at 1,247 m, but the volcano's true base sits on the floor of the Pacific Ocean over 5,000 m below sea level. Measured from base to top, Kilauea is over 6,000 metres tall, taller than most of the Andes. Together with Mauna Loa next door, Kilauea is part of one of the largest volcanic structures on Earth.

Deeper dive: the Hawaiian hot spot and the future of the islands

The Hawaiian islands are one of the clearest examples of how a stationary mantle hot spot can build a chain of volcanoes as the tectonic plate above it slowly drifts past. The hot spot itself has been in roughly the same location for at least 70 million years; the Pacific Plate has been drifting northwest over it the whole time.

The result is the long chain of Hawaiian islands and submerged seamounts:

• The Big Island of Hawaii: youngest, still volcanically active (Kilauea, Mauna Loa, Mauna Kea, Hualalai, Kohala).
• Maui: approximately 1 million years old. One semi-active volcano (Haleakala).
• Oahu: approximately 3 million years old. Volcanoes extinct.
• Kauai: approximately 5 million years old. Volcanoes long extinct, deeply eroded.
• Beyond Kauai, a chain of progressively older submerged seamounts called the Emperor Seamount Chain stretches northwest for 6,000 km, all the way to the Aleutian Trench off Alaska. The oldest seamounts are approximately 80 million years old.

Looking to the future: the next Hawaiian island is already forming. Kamaehuakanaloa (formerly called Loihi) is an active underwater shield volcano approximately 35 km southeast of the Big Island. Its summit is still 975 metres below sea level, but it is steadily growing. In another 10,000 to 100,000 years (a blink in geological time) it will rise above the waves and become the newest Hawaiian island. The hot spot keeps on building.

For more, see types of volcano and magma vs lava.