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Kilauea

Lava Continues to Pour into the Ocean

The update below is current as of July 16, 1999. This extended update is changed about every 4 to 6 weeks; more frequent updates will be made when there are drastic changes in activity or when residential areas are threatened by lava flows. Update archive.

Aerial view of lava bench, south coast of Kilauea Volcano
Photograph taken on July 8, 1999
New surface flows reached the lava bench and ocean on June 20 or 21 following a brief pause in the supply of magma to Pu`u `O`o vent between June 14 and 17.

Overview

Little has changed in the eruption of Pu`u `O`o in the past several weeks. Lava continues to travel through the lava-tube system from Pu`u `O`o to the coast and build new land, called a lava bench, into the ocean. Frequent collapses of the bench into the sea prevent the bench from extending seaward more than about 200 m from the former shoreline. Slow-moving pahoehoe flows continue to occasionally break out from the tube system on the broad coastal plain, and the 24th pause in the current eruptive episode occurred June 14-17. No significant changes have occurred at the Pu`u `O`o vent in the past several months, but scientists have recently identified a few new collapse structures on the south flank of the cone.

Aerial view of lava bench and coastal plain, Kilauea Volcano
July 1, 1999
Aerial view of the lava bench, coastal plain, Pulama pali, and Pu`u `O`o vent, Kilauea Volcano.
 
[Medium-sized image]
[Large-sized image]

24th Pause of Episode 55

What happens when lava stops flowing from the Pu`u `O`o vent into the lava-tube system? Is the supply of magma from the summit reservoir to the east rift zone reduced or is it completely shut off? Or is there a blockage directly beneath Pu`u `O`o?

Data from our new tiltmeter near Pu`u `O`o and at the the summit caldera suggest that during pauses 23 and 24, some magma was still moving into the east rift zone near Pu`u `O`o (see map at right and graph of tilt below).

 

Tilt of ground at summit and near Pu`u `O`o, pause 24
Graph of ground tilt at the summit of Kilauea Volcano
 

The pause began when a tiltmeter at the summit showed an outward tilt of the ground, which is represented by the increase in tilt of the top curve. This outward tilt indicates that magma was moving into the summit reservoir and accumulating there during the pause. Just after the beginning of the pause, the tiltmeter near Pu`u `O`o recorded a slight increase in tilt of the ground away from the east rift zone. This tilt indicates that some magma was probably still moving into the rift zone at the same time that magma was accumulating in the summit reservoir.

The reversal in tilt, both at the summit and near Pu`u `O`o, at the beginning of this pause indicates that magma was moving into the east rift zone. We infer that the pause was likely related to a blockage that developed beneath Pu`u `O`o or immediately uprift. This tilt reversal pattern was also seen during the eruptive pause in May 1999.

Pause ends as lava enters tube system from Pu`u `O`o

Lava tube skylight, Kilauea Volcano
Lava pours through tube
system after pause
Pahoehoe flow, Kilauea Volcano
Pahoehoe flows break out from
tube system after pause
[Medium-sized image]
[Large-sized image]
[Medium-sized image]
[Large-sized image]

Lava bench continues to grow and collapse

View of the active lava bench on the south coast of Kilauea Volcano
Photograph by J. Kauahikaua on June 24, 1999

This view of the lava bench is toward the southwest. The bench is about 200 m wide from the cliff to its seaward edge. Recent surface flows have poured over the cliff and made it easy for visitors to walk onto the dangeous bench unknowingly. Visitors to the entry area are advised to remain behind the warning signs posted by Hawai`i Volcanoes National Park.

The leading edge of the bench collapsed during the night of July 2-3. Scientists estimate that up to 75 m of the bench slid into the ocean, removing about 1.7 ha (4.1 acres) of new land or 20 percent of the bench. Strong explosions occurred intermittently during the next few days, reaching a climax on July 4th. Here is a description from a scientist who witnessed these explosions:

"Major explosions and jetting started on the bench at 6:14 p.m. Bubble bursts were occurring from 3 locations and lava fountaining was occurring from a vent on the western part of the bench. Lava was thrown up to 150 m into the air by the fountaining. The fountain produced a nested pair of cones, approximately 30-45 m in diameter and 5-7 m tall. The bubble bursts took place about 20-40 m inland of where the waves could reach. The bubbles were about 40 m in diameter, but a few reached 60 m."

"Most impressive was watching the entire cone and surrounding bench undulate like a liquid during the most vigorous bubble-burst activity. Between explosive episodes, a series of surface flows broke out, covering most of the visible bench. One flow that poured into the ocean built a tube through the surf, which led to a series of underwater explosions about 25 m offshore."

"We were also able to see the fireworks above Hilo Bay, but Pele's show was by far much better!"

Woman falls into crack near lava bench

At 9:40 p.m. on Tuesday, June 29, Hawai`i Volcanoes National Park rangers received word from Hawai`i County 911 dispatch that a woman had fallen into a deep crack near the edge of the cliff above the lava bench. She fell about 10 m into the crack, landing on a narrow ledge and sustaining injuries to her head and legs. She was pulled from the crack by park rangers and a Hawai`i County fire fighter, airlifted by helicopter to the end of the Chain of Craters road, then transported by County ambulance to Hilo Medical Center.

The woman was with a group of 4 others that had read, but disregarded, signs posted near the ocean entry flow field that noted "Area Closed - Do Not Enter."

In a press release, Park Superintendent Jim Martin expressed "concern over visitors ignoring warning signs. While understanding a visitor's desire to get up close to molten lava, the "Closed Areas" have been designated through ongoing consultation with scientists at the U.S. Geological Survey's Hawaiian Volcano Observatory, and try to provide for the best possible viewing with reasonable safety."

Martin said that "anyone who plans to hike toward the active lava flow area should have a reliable flashlight and extra batteries, three quarts of water, sun and rain protection, and sturdy boots. Those who head out in the late afternoon should have warm clothing and enough food and water to get them through a night on the flow field if they become disoriented trying to hike back to their car or lost during frequent white-outs. Sitting it out until sunrise is the simplest, and safest, way to survive such a predicament."

Learn more about hazards near the lava bench: explosions, collapses, and hot water.

 

Pits and craters on south flank of Pu`u `O`o

View of the south flank of Pu`u `O`o, Kilauea Volcano
Photograph by J. Kauahikaua on July 1, 1999
Fume rises from shallow collapse pits on south flank of Pu`u `O`o

Many small pits have formed on the lava shield on the west and south side of Pu`u `O`o during the past couple of years. In early June, a new collapse pit about 8 m in diameter and 5 m deep was observed; flowing lava was visible briefly at the bottom of the pit a few days later. Puka nui, a large collapse pit on the southwest flank of Pu`u `O`o, has not changed in the past two months.

 

Flow-field Map

Map of lava flow inundation 1983-July 1, 1999
Map showing area covered by lava flows emplaced during the Pu`u `O`o - Kupaianaha eruption between 1983 and July 1, 1999. Flows active between March 28 and July 1, 1999, are shown in pink. The tube delivers lava to the ocean a few hundred meters west of a prominent littoral cone (star) at Kamokuna (click map for a larger view of the map).

Update Archive


Eruption-viewing opportunities change constantly, so those readers planning a visit to the volcano should contact Hawai`i Volcanoes National Park for the most current eruption information (tel. 808-985-6000).


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Updated: 17 July 1999