Prior to the Mauna Ulu eruption, Chain of Craters Road continued east to Makaopuhi Crater and down to the coast. It passed Aloi and Alae, two pit crater, and Puu Huluhulu, a pre-historic cinder and spatter cone. The Mauna Ulu eruption began on May 24, 1969.
The Mauna Ulu eruption ended on July 22, 1974. Kilauea Volcano had erupted for nearly 5 years at a vent on the East Rift Zone of the volcano. This was the longest flank eruption of a Hawaiian volcano in historical time (a record that has been broken by the current eruption. It dramatically changed the landscape by covering large areas with lava, filling two pit craters, constructing a new vent, and adding land onto the island.
The eruption began as a fissure between Aloi and Alae pit craters. This area became the focus of future activity that would construct the Mauna Ulu shield. This photo was taken from above Alae Crater looking east to Aloi Crater. Chain of Craters Road is on the left. The fissure is near the center of the photo. Photograph by Don Swanson, U.S. Geological Survey, May 25, 1969.
The early episodes of the Mauna Ulu eruption produced numerous high lava fountains. Some of the fountains reached heights of 1,800 feet (540 m). This photo was taken from Puu Huluhulu. Photograph by Don Swanson, U.S. Geological Survey, August 22, 1969.
Different phases of the eruption were separated by pauses. During a pause, no lava was supplied to the vent. This photo shows a geologist examining a vent at Alae. Photograph by Don Swanson, U.S. Geological Survey, July, 1969.
The onset of the Mauna Ulu eruption was marked by 875 days of nearly continuous activity. During this period, both Alae and Aloi craters were filled with lava. This photo shows a low lava fountain generating lava flows which cascade into Aloi Crater. Photograph by Don Swanson, U.S. Geological Survey, December 30, 1969.
The steady supply of lava produced conditions that favored the development of long lava tube systems. Tubes extended from Mauna Ulu to the ocean, a distance of 6 miles (10 km). Skylights, holes in the tops of tubes, provide volcanologists windows into the shallow plumbing of the volcano. This volcanologist is determining the depth of the lava in the tube. Measurements of the cross-sectional area of the tube and the velocity of the lava provided an estimate of the volume of lava erupted. Photograph by Robert Tilling, U.S. Geological Survey, January 1, 1973.
Tube-fed lava flows buried Chain of Craters Road at several different locations. Note section of road at lower elevation in top right corner of photo. Photograph by Don Swanson, U.S. Geological Survey, February 15, 1971.
Several flows poured down the steep slopes of Poliokeawa and Holei Pali to produce beautiful deltas of shiny pahoehoe and dark aa lava. The flows in this photo drape Kealakomo Pali. Photograph by Don Peterson, U.S. Geological Survey, April 12, 1971.
The increase in velocity associated with moving down the steep slopes caused many flows to change from pahoehoe to aa. The aa flow in this photo is near the base of Holei Pali (seen in the background). Photograph by Don Peterson, U.S. Geological Survey, February 28, 1971.
Lava entered the ocean and added new land to the island at many different locations during the course of the eruption. This lava entry is near the Kealakomo village site, which was buried by lava in 1971. Photograph by Don Swanson, U.S. Geological Survey, March 3, 1971.
Following a six month hiatus in eruption, activity resumed at Mauna Ulu in February 1972. Like the previous period of continuous activity, lava traveled in a tube from the lava lake at the summit of Mauna Ulu to a lava lake at the location of Alae Crater. Overflows of this lava lake built a second shield adjacent to Mauna Ulu. This photo shows the Mauna Ulu vent. Alae lava lake is to the right of the center of the photo. Makaopuhi Crater is in the top right corner. Photograph by Don Swanson, U.S. Geological Survey, February 28, 1972.
Unlike the current eruption, where the active vent is in a remote location, the vent for the Mauna Ulu eruption was accessible. Park visitors could stand on the edge of the vent and peer into lake of lava. Photograph by Robin Holcomb, U.S. Geological Survey, March 23, 1973.
In April of 1973, a magnitude 6.3 earthquake occurred on the island of Hawaii. This earthquake apparently caused changes in the plumbing system of Kilauea Volcano. Lava drained from Mauna Ulu and an eruption began at Hiiaka and Pauahi craters. Lava returned to Mauna Ulu two days later but activity was sluggish. Late in 1973 and continuing into 1974, the intensity of activity increased. The lava lake overflowed and lava fountains reached heights of 250 feet (80 m). This photo shows the Mauna Ulu lava lake overflowing. Kane Nui o Hamo, a 500-750 year old shield-shaped vent, is on the horizon. Photograph by Robert Tilling, U.S. Geological Survey, November 5, 1973.
The Mauna Ulu eruption ended on July 19, 1974. Lava drained from the vent and the summit of Kilauea deflated. A short time later an eruption began at Keanakakoi Crater.
Continuing on Chain of Craters Road just down from the short side road is a pulloff in 1969 lava flows. These lava flows are some of youngest of the Mauna Ulu eruption. This is a great place to explore. Pyroclastics from the Mauna Ulu eruption can be found down in the cracks and on some surfaces.
Pele's tears are droplets of lava that solidified while flying through the air. They are black and commonly shaped like tear drops. Like obsidian, Pele's tears are glassy. However, obsidian is made of rhyolite, not basalt. (The only obsidian on the island of Hawaii is at Puu Waawaa).
Reticulite is basaltic pumice. When it was thrown from the volcano it was full of gas. The gas took up a lot of space. When the reticulite cooled it was very light because of the open space.
Pele's hair is a natural spun glass formed by blowing-out during quiet fountaining of fluid lava, cascading lava falls, or turbulent flows.
Enjoy looking at the rocks but remember that it is a federal offense to take anything from a national park.
Lava overflowed the Mauna Ulu vent several times in 1974 and sent flows down the flank of the volcano. Muliwai O Pele (river channel of Pele) is a typical aa flow. It has a broad channel contained by levees made of clinkery lava. Numerous accretionary lava balls are within the channel. The channel is 40 feet (12 m) across and 15 feet (5 m) deep. Note the person on the left for scale.
The steam plume generated by the lava entering the ocean is often visible from the pullout at the hairpin turn. This view provides rangers and volcanologists with an early indication of where and what the eruption is doing. If the plume is absent, it may indicate that there is a pause in the eruption.
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