On January 3, 2003, Kilauea Volcano, perhaps the world’s most active volcano on the Island of Hawai`i, will have been erupting continuously for 20 years. Since the eruption began in 1983, lava flows have covered 43 square miles of the volcano, added nearly 550 acres to the island, created local volcanic air pollution known as "vog," and drawn millions of people to experience and enjoy volcanic activity. “This is the longest eruption on the east rift zone in at least the past 600 years, and there is no any sign that it will end soon,” according to Don Swanson, USGS Scientist in Charge of the Hawaiian Volcano Observatory. “Our monitoring shows that the output of lava remains high, typically 400,000 to 450,000 cubic yards each day. This is equivalent to 40,000 to 45,000 dump truck loads every day, or about 1 dump truck of lava every 2 seconds!”

USGS scientists at the Hawaiian Volcano Observatory monitor Hawai`i’s active volcanoes, including Kilauea and nearby Mauna Loa, the world’s largest volcano. Throughout the ongoing eruption, USGS scientists have provided information about Kilauea’s changing and sometimes hazardous activity to officials of Hawai`i County Civil Defense and Hawai`i Volcanoes National Park, as well as to the general public. “We are ready 24-7 to detect and analyze sudden changes in the eruption in order to forecast any change in the location and direction of lava flows, and whether or not a new vent has opened up on the rift zone or elsewhere on the volcano,” said Swanson. “People look to us to report on the status of Hawai`i’s volcanoes, and Kilauea in particular because of its long eruption.”

Named after the two main vents of the eruption, the Pu`u `O`o-Kupaianaha eruption has progressed through three main periods of activity. “The early years of the eruption are vividly remembered for lava fountains as high as 1,500 feet that spewed every three to four weeks from the Pu`u `O`o vent and built the largest cone on the east rift zone 835 feet high,” said USGS geologist Christina Heliker. “Then, in mid-1986, the eruption shifted 2 miles eastward to Kupaianaha, and lava poured from the new vent continuously for 5 1/2 years. This was the most destructive period of the eruption.” As lava moved seaward from Kupaianaha, flows repeatedly invaded communities on Kilauea's southern coast, destroying Kapa`ahu and Kalapana and closing the coastal highway.

Finally, the eruption returned to the Pu`u `O`o cone in 1992, where it remains today. "Because lava has poured continuously from vents on the south and west sides of the tall cone for the past 10 years, the summit of the cone lost support and collapsed, and a broad cone 260 feet has grown on the side of Pu`u `O`o,” according to Heliker. The newest of these fissures became active on May 12, 2002, and is now sending lava through a 7-mile-long series of lava tubes to the sea. When new flows entered the ocean in July and August, thousands of people came to experience molten rock oozing across the ground.

More than 540 acres of new land have been created as lava is added to the shoreline. Deltas of new land form above steep submarine slopes of lava rubble. Such steep slopes are unstable and prone to slumping, so deltas often collapse. The most recent collapse occurred on December 15, when about 27 acres dropped into the sea in a few minutes. Large collapses are dangerous and often cause violent steam explosions and scalding waves. Four people have died in the past 10 years because of activity on Kilauea’s lava deltas.

Since late 1986, lava has poured into the ocean more than 70 percent of the time, by far the longest such interval in at least 600 years. The total volume of lava produced by this eruption is 0.6 cubic miles, more than half the amount of lava erupted by Kilauea in the last 160 years.

About 1,800 tons of sulfur dioxide gas are given off each day of the eruption. The gas has resulted in volcanic smog, or "vog," downwind of the volcano. Vog aggravates preexisting respiratory ailments and damages crops. Acid rain caused by vog leaches lead from roofs and solder, contaminating household water-catchment supplies.

Since early 1992, lava flows have remained mostly within Hawai`i Volcanoes National Park, though one adjacent residential area has been repeatedly hit by flows. The geologic history of Kilauea indicates a high likelihood of eruptions in populated areas some time after the present activity ends. “Major eruptions of this type might end abruptly or diminish over many months,” said Swanson. “No one could have predicted that this eruption would last for 20 years. Its future remains equally uncertain, so we must be vigilant.”

For more information on Kilauea Volcano and the ongoing eruption, please visit http://hvo.wr.usgs.gov/.

The USGS, a bureau within the Department of the Interior, serves the Nation by providing reliable scientific information to describe and understand the Earth; minimize loss of life and property from natural disasters; manage water, biological, energy, and mineral resources; and enhance and protect the quality of life.