During the past week, lava has risen within the Overlook crater (active vent at the summit of Kilauea) and overflowed onto the floor of the larger Halema‘uma‘u Crater. As a result, visitation to Hawaii Volcanoes National Park has skyrocketed. This is understandable because it’s the first time a lake of lava within Halema‘uma‘u Crater has been visible from park visitor overlooks since 1974.
The Overlook crater opened March 19, 2008, but until this week, only the gas plume and nighttime glow from the vent was visible. Through the years, the vent opening enlarged as parts of its rim spalled off and dropped dramatically into the lava lake. Today, the opening is about 160 m (175 yds) wide and about 220 m (240 yds) long, and the lava lake within it slowly circulates — ascending in the north and descending in the south.
This is the16th lava lake hosted in Halema‘uma‘u Crater since the explosions of May 1924, which doubled the crater’s width and increased its depth to about 410 m (450 yds).
From 1924-34, seven lava lakes occurred in Halema‘uma‘u, each lasting from two to 33 days. After 1934, Kilauea was completely inactive until June 27, 1952, when an active lava lake reoccupied Halema‘uma‘u for 136 days. Four more short-lived lava lakes popped up in the crater in 1954 and 1961. Accumulation of lava from these 11 lakes decreased the depth of Halema‘uma‘u Crater to 170 m (186 yds).
In early November 1967, another lava lake was created by an eruption that occurred in phases during a period of 251 days. By the time the eruption ended July 13, 1968, Halema‘uma‘u Crater had been filled with another 100 m (110 yds) of lava.
The 1967-68 eruption produced perched lava lakes or ponds. These are bodies of circulating lava that build their own rims, much like an above-ground swimming pool. The 1967-68 eruptive phases typically started with lava erupting from, and covering most of, the Halema‘uma‘u Crater floor before being confined within its perched boundaries. The rest of the eruptive phase would consist of stationary and migrating spattering sources, or low lava fountains, within the perched circulating lava lake.
Not long after the 1967-68 summit eruption ended, activity picked up in Kilauea’s upper East Rift Zone, where, in 1969, the Mauna Ulu eruption began. Twenty-nine months later, Mauna Ulu activity waned and Kilauea’s summit started to inflate rapidly. On August 14, 1971, a brief fissure eruption occurred in the east summit caldera. This was followed in September by a five-day eruption in the Southwest Rift Zone and within Halema‘uma‘u Crater, where lava fountains filled a broad ring along the outer edges of the crater before the summit activity ceased.
But changes within Halema‘uma‘u Crater were not only because of lava filling. By the end of the September 1971 eruption, the central part of the floor, still covered with 1968 lava, had dropped 45 m (49 yds), leaving a 150-m- (165-yd-) wide bench of lava about halfway up the crater walls. The bench now is narrower, but still can be seen about halfway up the walls of Halema‘uma‘u Crater.
In February 1972, eruptive activity resumed at Mauna Ulu in Kilauea’s upper East Rift Zone and continued until late July 1974. This was followed by three brief eruptions at the summit and upper Southwest Rift Zone of Kilauea. The second of these eruptions included a fissure that crossed the floor of Halema‘uma‘u Crater on Sept. 19, 1974. But unlike the September 1971 eruption, the September 1974 eruption remained within Kilauea Caldera.
The 1974 fissure erupted for less than half a day, but lava covered the Halema‘uma‘u Crater floor — except for the tops of three high spatter cones formed in the 1967-68 eruption — before the lava level dropped about 7 m (8 yds). The current floor of Halema‘uma‘u Crater is what remains of the September 1974 eruption.
Today’s Overlook crater lava lake (2008-present) in the floor of Halema‘uma‘u Crater already has outlasted all other Halema‘uma‘u lava lakes since 1924.
Will it continue to build a perched lava lake on the Halema‘uma‘u Crater floor? Or will the lava lake collapse back into the crater in response to another rift zone breakout?
Whatever happens, USGS Hawaiian Volcano Observatory scientists will be closely watching and documenting the activity.
Kilauea activity update
Kilauea’s summit lava lake rose during the past week, tracking summit inflation, and began to overflow sporadically, starting Tuesday. However, as of this writing (Thursday), the summit had begun to deflate slowly and the lava lake level had dropped slightly. As of Thursday, seismicity at the summit and along the upper East and Southwest Rift Zones was elevated during the past week.
Kilauea’s East Rift Zone lava flow continues to feed widespread breakouts northeast of Pu‘u ‘O‘o. The most distant extent of the currently active breakouts was 8.3 km (5.2 mi) from Pu‘u ‘O‘o on Wednesday, based on satellite imagery.
Two earthquakes were reported felt on the Big Island in the past week. At 7:35 a.m. Wednesday, a magnitude 3.0 earthquake occurred 2.1 km (1.3 mi) southeast of Kilauea Summit at a depth of 1.0 km (0.6 mi). At 9:16 a.m. Wednesday, a magnitude 3.4 earthquake occurred 6.4 km (4.0 mi) north of Ka‘ena Point at a depth of at 7.3 km (4.5 mi).
Visit the HVO website (http://hvo.wr.usgs.gov) for past Volcano Watch articles, Kilauea daily eruption updates and other volcano status reports, current volcano photos, recent earthquakes and more; call 808-967-8862 for a Kilauea summary update; email questions to askHVO@usgs.gov.
Volcano Watch (http://hvo.wr.usgs.gov/volcanowatch/) is a weekly article and activity update written by scientists at the U.S. Geological Survey`s Hawaiian Volcano Observatory.
