Puʻu ʻŌʻō (also spelled Pu‘u‘ō‘ō, and often written Puu Oo, pronounced [ˈpuʔu ˈʔoːʔoː], poo-oo-OH-oh) is a volcanic cone on the eastern rift zone of Kīlauea volcano in the Hawaiian Islands. The eruption that created Puʻu ʻŌʻō began on January 3, 1983, and continued nearly continuously until April 30, 2018, making it the longest-lived rift-zone eruption of the last two centuries. By January 2005, 2.7 cubic kilometers (0.65 mi3) of magma covered an area of more than 117 square kilometers (45 mi2) and added 230 acres (0.93 km2) of land to the southeast coast of Hawaiʻi. The eruption claimed at least 189 buildings and 14 kilometers (8.7 mi) of highways, as well as a church, a store, the Wahaʻula Visitor Center, and many ancient Hawaiian sites, including the Wahaʻula heiau. The coastal highway has been closed since 1987, as parts of the road have been buried under lava up to 35 meters (115 ft) thick.
Etymology The hill was initially nicknamed "Puʻu O" by volcanologists, as its position when marked on a map of the area coincided with an "o" in "Lava flow of 1965". Later, the elders of the village of Kalapana were asked to name the new hill, and chose Puʻu ʻŌʻō, meaning hill of the digging stick. The name is also often translated as "Hill of the ʻŌʻō Bird". In 2021, the Hawaiʻi Board of Geographic Names updated the spelling of the cone as Pu‘u‘ō‘ō for consistency with the board's spelling guidelines. The Hawaiian Volcano Observatory began following the new recommended naming convention shortly thereafter.
Geologic history
1983–1986: High lava fountains build tall cinder and spatter cone
The Puʻu ʻŌʻō eruption began when fissures split the ground in the remote rainforest of the eastern rift zone, on January 3, 1983. By June 1983, the activity had strengthened and localized to the Puʻu ʻŌʻō vent. Over the next three years, 44 eruptive episodes with lava fountains as high as 460 meters (1,510 ft) stopped traffic at points across east Hawaiʻi. The fallout of cinder and spatter from the towering lava fountains built a cone 255 meters (837 ft) high.
1986–1991: Eruption shifts east to Kūpaʻianahā In July 1986, the conduit feeding magma to Puʻu ʻŌʻō ruptured, and the eruption abruptly shifted 3 kilometers (1.9 mi) downrift to form the Kūpaʻianahā vent. With the new vent came a new style of eruption: continuous, quiet effusion from a lava lake replaced the episodic high fountaining. After a few weeks, a roof formed over the main lava outflow channel, which created a lava tube. The lava tube allowed the fluid pahoehoe lava to retain heat and flow long distances. In less than a year, overflow from the lake created a broad and low shield about 55 meters (180 ft) above Kūpaʻianahā. Lava streams were first visible from the town of Kapaʻau in November, 1986. In the course of that month, lava cut a swath through Kapaʻahu, covered the coastal highway, and finally reached the ocean 12 kilometers (7.5 mi) from the vent. Some weeks later, the lava flow shifted eastwards and buried 14 houses in the town of Kalapana within one day. The lava flow at Kalapana ceased when the lava tube system shut down.
In 1990, the eruption entered its most destructive phase, when flows turned eastward and completely destroyed the villages of Kalapana and Kaimū. Kaimū Bay and Kalapana Black Sand Beach were also completely covered with lava. Over 100 homes were destroyed by the ever-broadening flow field in a nine-month period. New tubes diverted lava away from Kalapana early in 1991, and lava once again entered the ocean within Hawaii Volcanoes National Park.
1992–2013: Steady lava effusion The volume of lava erupted from Kūpaʻianahā declined steadily through 1991, and in early 1992, the vent died. The eruption then returned to Puʻu ʻŌʻō, where flank vents on the west and southwest sides of the cone constructed a new lava shield. Soon lava tubes were feeding lava from the vents to the ocean, with few surface flows in between. The flank vents have held center stage ever since, with the exception of a two-month pause in activity, early in 1997, which followed a brief fissure eruption in Nāpau Crater, a short distance southwest of Puʻu ʻŌʻō. On the evening of January 29, 1997, a series of earthquakes struck Kīlauea's east rift zone. Deep within the rift zone, magma was escaping from the conduit leading to the Puʻu ʻŌʻō vent, cutting off the supply to the ongoing eruption. The lava pond at Puʻu ʻŌʻō drained, and residents 10 miles (16 km) away heard a low, rumbling roar as the crater floor dropped 500 feet (150 m) and the west wall of the Puʻu ʻŌʻō cone collapsed. A few hours later, as magma found a new path to the surface, the ground cracked in nearby Nāpau Crater, and lava fountains lit up the night sky. However, activity in this area was short-lived, and the center of activity soon shifted back to Puʻu ʻŌʻō.
As of January 2007, 3.1 cubic km of lava had covered 117 km2 (45 sq mi) and added 201 hectares (500 acres) to Kīlauea's southern shore. The new shoreline was 15.6 km (9.7 mi) long. The lava flows have destroyed 189 structures and covered 14 km (8.7 mi) of highway with as much as 35 m (115 ft) of lava. In 2007, after a cluster of earthquakes, activity in Puʻu ʻŌʻō subsided and the crater floor collapsed, with no incandescence visible in the crater after the end of August. Lava began emerging from a series of cracks in the northeast rift zone and spread slowly east and south as a perched flow, with slow advances of ʻaʻā. The flow spread mostly over flows of 1983–1986, with minor incursions into adjoining forests.
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