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Summary of the Pu`u `O`o-Kupaianaha Eruption, 1983-present

The Pu`u `O`o-Kupaianaha eruption of Kilauea, now in its nineteenth year and 55th eruptive episode, ranks as the most voluminous outpouring of lava on the volcano's east rift zone in the past five centuries. By September 2002, 2.3 km³ of lava had covered 110 km² and added 220 hectares to Kilauea's southern shore. In the process, lava flows destroyed 189 structures and resurfaced 13 km of highway with as much as 25 m of lava.

Beginning in 1983, a series of short-lived lava fountains built the massive cinder-and-spatter cone of Pu`u` O`o. In 1986, the eruption migrated 3 km down the east rift zone to build a broad shield, Kupaianaha, which fed lava to the coast for the next 5.5 years. When the eruption shifted back to Pu`u `O`o in 1992, a series of flank-vent eruptions formed a shield banked against the uprift side of the cone. Continuous eruption from these vents undermined the west and south flanks of the cone, resulting in large collapses of the west flank.

In May 2002, a new vent opened on the west side of the shield and fed flows down the western margin of the flow field, sparking the largest forest fire in the park in 15 years. These flows reached the ocean near the end of Chain of Craters Road in July, and as many as 4,000 visitors per day flocked to view flowing lava up close for the rest of the summer.

Resources

• Current map of flow field
• Map of Kilauea Volcano
• Current table of eruption statistics
• Sketch of magma reservoir system and lava tubes

Eruption summary

• 1983-1986, The rise of Pu`u `O`o
• 1986-1991, Eruption shifts to Kupaianaha
• 1992-1994, Eruption returns to Pu`u `O`o
• 1995-1998, The fall of Pu`u `O`o
• 1999-2000, Intrusion triggers pause in eruption

1983-1986, The rise of Pu`u `O`o: episodic lava fountains build massive cone

The Pu`u `O`o-Kupaianaha eruption began on January 3, 1983. For the first six months, fissures erupted intermittently along the middle east rift zone from Napau Crater to Kalalua (eruptive episodes 1-3). In June 1983, the activity became localized at the Pu`u `O`o vent, which straddles the boundary of Hawai`i Volcanoes National Park. For the next three years (episodes 4-47), Pu`u `O`o erupted approximately every three to four weeks, usually for less than 24 hours at a time. These eruptive episodes were characterized by spectacular lava fountains that catapulted lava as high as 470 m above the vent.

The high fountains produced mainly `a`a flows, the more viscous and crystalline of the two types of Hawaiian lava. `A`a flows from Pu`u `O`o were typically 3-5 m thick and advanced at speeds of 50-500 m/hr, picking up speed and narrowing on steep slopes. Because of the short duration of each eruptive episode, none of these flows reached the ocean or the coastal highway. The flows posed an immediate threat, however, to the sparsely populated Royal Gardens subdivision, located on a steep slope 6 km southeast of the vent. `A`a flows reached the subdivision in as little as 13 hrs during several eruptive episodes. They destroyed 16 houses in 1983 and 1984.

Fallout from the towering lava fountains built a cinder-and-spatter cone 255 m high, over twice the height of any other cone on the east rift zone. The cone was strikingly asymmetric, because the prevailing trade winds caused most of the airborne fragments to pile up on the southwest side of the conduit.

1986-1991, Eruption shifts to Kupaianaha: continuous effusion sends lava to the sea

In July 1986, the vertical conduit of Pu`u `O`o ruptured and the eruption shifted to a new vent, Kupaianaha, 3 km northeast of Pu`u `O`o. This marked the end of episodic high fountaining and the beginning of five-and-a-half years of nearly continuous, quiet effusion (episode 48). A lava pond formed over the new vent, and its frequent overflows built a broad, low shield that reached its maximum height of 55 m in less than a year.

After weeks of continuous eruption, the main channel exiting from the pond gradually developed a roof as crust at the sides of the channel extended across the lava stream, forming the beginning of a lava tube. Lava tubes insulate rivers of lava from heat loss, producing pahoehoe, a type of lava more fluid than `a`a. The surface of a cooled pahoehoe flow can be flat and smooth, ropy, or undulating.

A broad field of tube-fed pahoehoe spread gradually toward the coast, 12 km to the southeast, taking three months to cover the same distance that `a`a flows from Pu`u `O`o traveled in less than a day. By early November 1986, the flows were visible on the steep slope above the small community of Kapa`ahu, and their leisurely pace was no longer reassuring.

Late in November 1986, flows from Kupaianaha reached the ocean, cutting a swath through Kapa`ahu and closing the coastal highway. A few weeks later, the lava took a more easterly course and overran 14 homes on the northwest edge of Kalapana in a single day. Luckily for the rest of the village, this flow abruptly stagnated when the tube became blocked near the vent.

Over the next three years, lava destroyed homes on either side of the ever-widening flow field. Initially, the course of the pahoehoe flows was strongly influenced by pre-eruption topography, but eventually even the highest ground was inundated. This was not only because pahoehoe re-covered many areas repeatedly, but also because the tube-fed flows thickened from within, inflating as more lava was intruded under the already solid crust of the flow front.

From mid-1987 through 1989, most of the lava erupted from Kupaianaha flowed directly to the sea. Steam explosions at the ocean entry fragmented the lava, creating black glassy sand that collected to form new beaches in protected bays down-current from the lava entry. New, albeit unstable, land was added as lava built a series of benches seaward over a steep submarine slope of fragmented lava (see hazards associated with collapsing and exploding lava benches).

The long-lived tube system delivering lava to the ocean began to break down in the spring of 1989, and surface flows were a common sight, particularly on the steep slope (Pulama pali) above the coastal plain. Lava flows encroached on new territory, overrunning the Waha`ula Visitor Center and adjoining residences in Hawai`i Volcanoes National Park.

The eruption began to change in 1990, when a series of 12 pauses, lasting from 1-4 days, interrupted the steady effusion of lava. At the same time, the eruption entered its most destructive period. In March 1990, the flows turned toward Kalapana, an area cherished for its historic sites and black sand beaches. By the end of the summer, the entire community, including a church, store, and 100 homes, lay buried under 15-25 m of lava (see detailed summary). As the flows advanced eastward, they took to the sea, replacing the palm-lined Kaimu Bay with a plain of lava that extends 300 m beyond the original shoreline. In late 1990, a new lava tube finally diverted lava away from Kalapana and back into the national park, where flows once again entered the ocean.

During the five-and-a-half years that Kupaianaha reigned, repeated collapses of the Pu`u `O`o conduit gradually formed a crater approximately 300 m in diameter. A lava pond was present sporadically at the bottom of the crater starting in 1987; since 1990 it has been present much of the time.

The volume of lava erupted from Kupaianaha steadily declined through 1991. Concurrently the level and activity of the Pu`u `O`o lava pond rose. In November 1991, fissures opened between Pu`u `O`o and Kupaianaha and erupted lava for three weeks. Kupaianaha continued to erupt during this event (episode 49), but its output was waning. On February 7, 1992, the Kupaianaha vent was dead.

1992-1994, Eruption returns to Pu`u `O`o: flank vents build shield against uprift side of cone

Ten days after Kupaianaha stopped erupting, activity returned to Pu`u `O`o. Lava erupted in low fountains along a fissure on the west flank of the steep-sided cone. This was the first in a series of flank vents that have been active for eight years (episodes 50-53 and episode 55). As at Kupaianaha, the style of the eruption was nearly continuous, quiet effusion.

Episodes 50-53 built a lava shield 45 m high and 1 km in diameter that banked against the western flank of Pu`u `O`o. In November 1992, lava crossed the Chain of Craters Road in Hawai`i Volcanoes National Park and entered the ocean at Kamoamoa, 11 km from the vents. Over the next month, tube-fed pahoehoe flows buried the Kamoamoa archaeological site, the National Park's campground and picnic area, and a black sand beach formed earlier in the eruption when flows from Kupaianaha entered the ocean. From the end of 1992 through January 1997, lava tubes fed lava to the ocean almost continuously, broadening the Kamoamoa flow field, which lies mostly within the National Park.

Beginning in 1993, collapse pits appeared on the west flank of Pu`u `O`o as lava flowing from the flank vents downcut through tephra beneath the cone. In the next few years, the largest of these, known as the "Great Pit", would engulf most of the west flank.

1995-1998, The fall of Pu`u `O`o: collapse claims west flank of cone

On the night of January 30, 1997, Pu`u `O`o cone changed dramatically. Magma drained from the conduit of Pu`u `O`o, causing first the crater floor, and then the west wall of the cone, to collapse. Shortly thereafter, new fissures broke open and erupted briefly in and near Napau Crater. This event, designated episode 54, was over in 24 hours.

The collapse created a large gap in the west side of the cone, and the rubble-lined crater was now 210 m deep. For the next 23 days, no active lava was visible at the eruption site.

Episode 55 began on February 24, 1997, when a lava pond returned to the Pu`u `O`o crater. A month later, lava erupted outside the crater from new vents on the west and southwest flanks of the cone.

In April 1997, the active lava pond in Pu`u `O`o crater was replaced by a single vent in the western part of the crater, known as the "crater vent." Flows from the crater vent intermittently ponded in the eastern part of the crater. In mid-June 1997, the pond rose until it overtopped the gap in the west wall of Pu`u `O`o, and lava spilled from the crater for the first time in 11 years. Subsequent crater overflows sent lava over the east crater rim to form flows that spread as far as 1.5 km downrift. The spillovers were brief events, ending when the pond drained through conduits in the crater floor.

Tube-fed flows from the episode 55 flank vents added to the pre-existing Kamoamoa flow field, and lava reached the ocean in July 1997 near the eastern boundary of Hawai`i Volcanoes National Park. Lava poured into the ocean at two adjacent sites, Waha`ula and Kamokuna, through 1998.

The most spectacular event in 1998 was a surge in the supply of magma to Pu`u `O`o on January 14. Lava briefly overflowed the crater (the only time in 1998) and fountains and flows erupted from several collapse pits on the south flank of the cone. For the rest of the year, lava flowed from the south flank vents directly into the tube system.

Downcutting beneath the flank vents continued to remove support for the Pu`u `O`o cone. A new collapse pit, Puka Nui, began to form in December 1997 on the southwest flank of the cone. By the end of 1998, Puka Nui was more than 175 m in diameter.

1999-2000, Intrusion triggers pause in eruption: tube system blocked

On September 12, 1999, an earthquake swarm and deflation of the summit heralded an intrusion of magma in the upper east rift zone of Kilauea (see summary in eruption archive). The magma conduit supplying Pu`u `O`o was depressurized as magma was diverted into the upper east rift zone, and the normal supply of magma to the eruption was interrupted for 11 days. A sluggish lava pond appeared at the bottom of the Pu`u `O`o crater on September 14, but flows didn't erupt from flank vents until September 23, marking the end of the pause.

Prior to the intrusion, the lava tubes had been holding a steady course for 12 months, feeding lava to the coast where it entered the ocean at the Kamokuna site inside Hawai`i Volcanoes National Park. During the pause, however, the long-lived tube system became permanently blocked near the 2250 ft elevation, about 10 km from the coast. When the eruption resumed, surface flows broke out of the tube at this elevation. Over the next several weeks, hundreds of short surface flows built a series of shields that coalesced to form a prominent ridge along the axis of the tube.

Eventually, longer flows moved down the pali on the west and east sides of the episode 55 flow field. New tubes developed within these flows. Lava finally reached the ocean in mid December at Highcastle and Lae`apuki. The Highcastle entry was short lived, but the Lae`apuki entry continued into the new year. In February 2000, the eastern branch of the flow reached the ocean near the site of Waha`ula. By the end of March 2000, the Lae`apuki entry had died, and lava was spilling into the sea at several locations in the Waha`ula area.

References

Heliker, C., Mangan, M.T., and Mattox, T.N., 1998, The character of long-term eruptions: inferences from episodes 50-53 of the Pu`u `O`o-Kupaianaha eruption of Kilauea Volcano: Bulletin of Volcanology, v. 59, p. 381-393.

Heliker, C., and Wright, T.L., 1991, Lava-flow hazards from Kilauea: Geotimes, May 1991, p. 16-19.

Mattox, T.N., Heliker, C., Kauahikaua, J., and Hon, K., 1993, Development of the 1990 Kalapana flow field, Kilauea Volcano, Hawaii: Bulletin of Volcanology, v. 55, p. 407-413.

Wolfe, E.W. (ed), 1988, The Pu`u `O`o eruption of Kilauea Volcano: U.S. Geological Survey Professional Paper 1463, 251 p.