| Puʻu ʻŌʻō | |
|---|---|
View at dusk, June 1983 |
|
| Elevation | 2,290 ft (698 m) |
| Location | |
| Location | Hawaii County, Hawaii, USA |
| Range | Hawaiian Islands |
| Topo map | USGS Kalalua |
| Geology | |
| Type | Cinder/spatter cone |
| Age of rock | Almost 30 years |
| Volcanic arc/belt | Hawaiian-Emperor seamount chain |
| Last eruption | 1983- |
Puʻu ʻŌʻō (often written Puu Oo, and pronounced [ˈpuʔu ˈʔoːʔoː], roughly "poo-oo oh-oh") is a cinder/spatter cone in the eastern rift zone of the Kīlauea volcano of the Hawaiian Islands. Puʻu ʻŌʻō has been erupting continuously since January 3, 1983, making it the longest-lived rift-zone eruption of the last two centuries.
Although the name is often translated as "Hill of the ʻŌʻō Bird" from Hawaiian, there is a different explanation of the Hawaiian appellation.[1] The word ʻŌʻō also means digging stick.[2] Because in Hawaiian legends the volcano goddess Pele uses her magic rod pāoa[3] to create volcanic pits,[4] this seems to be the intention for the naming. The cone was originally informally called "Puʻu O" by volcanologists, who simply assigned letters to vents as they arose during the first part of the eruption.[5]
By January 2005, 2.7 cubic kilometers (0.65 cu mi) of magma covered an area of more than 117 square kilometers (45 sq mi) and added 230 acres (0.93 km2) of land to the Southeast coast of Hawaiʻi. So far, the eruption has claimed 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 it has been buried under lava up to 35 meters (115 ft) thick.
Contents |
The Puʻu ʻŌʻō eruption began when fissures split the ground in the remote rainforest of the eastern rift zone. 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.
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 Kapaʻahu 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 totally 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 the Hawaii Volcanoes National Park. 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 that 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 2008[update] Puʻu ʻŌʻō cone was in its twenty-fifth year and 57th eruptive episode. This is the largest volume of lava in the past five centuries to erupt from the volcano's east rift zone. For over a decade the eruption flowed from flank vents on the south and west sides of the cone.
As of January 2007, 3.1 cubic km of lava had covered 117 km2 (45 mi2) and added 201 hectares (500 acres) to Kīlauea's southern shore. The new shoreline is 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 forest.
In late July 2008, additional flows extended from the eastern vents of Puʻu ʻŌʻō and in October multiple new fissures opened along the length of the tube expanding into Royal Gardens Subdivision and covered a large area of the coastal flats in November, 2008.
On March 5, 2011, the floor of the Puʻu ʻŌʻō crater deflated, then collapsed. Two hours later, a new eruption occurred in Kilauea's middle east zone, between Puʻu ʻŌʻō and Napau Crater.[6] Lava fountains were reported to be 65 feet (20 m) high.
On March 26, 2011, lava began to refill the crater's floor being visible in USGS HVO webcam. USGS states that accumulation of lava has put the crater floor about 39 m (130 ft) below the eastern crater rim as of June 1.[7]
On September 21, 2011, lava in the W lava lake in Pu'u 'O'o Crater fed a series of lava flows that traveled down the W flank of Pu'u 'O'o during 20-21 September. At about 0225 on 21 September activity in the crater and overflows to the W suddenly decreased, as lava broke through the upper E flank of Pu'u 'O'o, bypassing the crater. The new fissure fed a channelized 'a'a lava flow that advanced rapidly downslope 2.5 km SE. A second flow to the W of the first began the next day. In addition, a small pad of lava actively refilled the bottom of the drained E lava lake and small flows were barely active at the W edge of Pu'u 'O'o Crater. The channelized 'a'a lava flow reached 3.7 km long on 23 September and then stalled within the Kahauale'a Natural Area Reserve. Most of the active lava spread S and W of Pu'u Halulu (1.3 km NE of Pu'u 'O'o) during 23-27 September. Minor lava activity resumed within Pu'u 'O'o Crater with short lava flows issuing from the base of the E wall on 25 September and from the W wall base during 25-26 September. The crater floor of Pu'u 'O'o slowly subsided. Lava activity resumed within the E lake on 26 September. The floor of the crater continued to subside during 26-27 September, opening up cracks in the N crater floor. [8] and [9]