The lava lake at Kilauea Volcano’s summit continues to spill over the Overlook Crater rim sending lava more than a football field’s length away.
Beginning at about 9:40 p.m. Tuesday and continuing through Thursday, the Overlook crater lava lake overflowed its rim on several occasions, sending short, lobate sheets of pahoehoe as far as 142 yards across the floor of Halemaumau Crater, U.S. Geological Survey Hawaiian Volcano Observatory scientists said. The floor is located about 279 feet below the crater’s rim. Jaggar Museum, located within Hawaii Volcanoes National Park, sits about 0.8 mile from the edge of Halemaumau Crater.
The brief overflows, captured on web cameras, also showed the forward motion cease as the lava lake level fell and lava subsided into the Overlook Crater, the scientists said. No change in lava spattering or surface circulation patterns on the lake in response to these overflows has been noted.
Scientists expect the overflows to continue intermittently given the sustained high, and slowly rising, levels of lava within the vent during the past week. Lava last covered the entire crater floor of Halemaumau in 1967 and 1968, nearly 50 years ago.
During similar lava lake activity at Halemaumau in the 1800s and early 1900s, scientists said lava lakes frequently produced overflows. Over time, the overflows and intermittent spattering can build a collar of solidified lava that then contains the rising and circulating lava lake, which is then called a “perched lava lake.”
The overflows occurred after a rockfall from the southeast wall of Halemaumau Crater that triggered an explosion from the lake surface about 10:20 a.m. Tuesday. Large clots of molten spatter up to six feet across were thrown to the rim of Halemaumau in the vicinity of the closed visitor overlook fence.
The hot spatter formed a nearly continuous blanket for about 110 yards along the crater rim and extended back from the rim up to 55 yards. Small bits of crater-wall rock were embedded in the spatter clots, scientists said.
Scientists expect that there will be additional explosions and showers of rock and spatter that can occur suddenly. The viewing area near the rim of Halemaumau was closed in 2007 because of sulfur dioxide levels and safety concerns. When the Overlook Crater vent opened just below the viewing area, it measured about 115 feet wide. Today, it is about 500 feet by 700 feet.
Visitors to the Jaggar Museum and other park areas should also note that with southerly wind conditions, similar rockfalls and explosions can result in a dusting of powdery to gritty ash composed of volcanic glass and rock fragments. Several of these events occurred this past weekend and, while a very minor hazard at this time, people should be aware that additional dustings of ash are likely at Jaggar Museum and other areas around the Kilauea summit.
The current rise in the lava lake level comes amid a period of inflation at Kilauea, which began abruptly on April 21. On Thursday morning, the volcano appeared to be deflating. During inflation, magma rises into the summit reservoir, according to the observatory. The summit reservoir enters the deflation portion of the cycle when the magma moves laterally into a rift zone and either erupts or is stored there.
“As long as magma supply is elevated, we expect continued high lava lake levels accompanied by additional overflows. Lava from these overflows could cover more of the Halemaumau Crater floor, form a perched lake, or result in some combination of these two processes,” scientists said Wednesday. “Spattering or lava fountaining sources can migrate across the surface of the lava lake, as recently observed. We expect continued rock falls, intermittent explosions and ash fall, and continued high levels of gas release.”
Shallow earthquake activity has increased beneath the summit caldera, upper East Rift Zone, and upper Southwest Rift Zone. Most of the temblors have had a magnitude less than 2.0. However, there have been a couple of earthquakes with a magnitude of at least 3.0.
Despite the elevated activity at Kilauea’s summit, scientists say there has been no obvious change in the eruption rate of lava from Puu Oo on the East Rift Zone. Rates of gas emission from both the summit and Puu Oo remain for the most part unchanged.
“The evolution of unrest in the upper East Rift Zone is less certain. It is possible that a surge of lava will reach Puu Oo and lava flow output will increase, both on the flanks and within the crater of Puu Oo. It is also possible that lava will form a new vent at the surface. If this happens, it will most likely occur along a portion of the East Rift Zone between Pauahi Crater and Puu Oo. Other outbreaks in the summit area or along either rift zone on Kilauea cannot be ruled out. If a new outbreak or surge in lava to Puu Oo occurs, we will expect a drop in the summit lava lake,” they said.
Pauahi Crater last saw an eruption in1979 that lasted 16 days. The present crater floor was created during a 31-day eruptiuon in the 1973. The crater is located about 6.6 miles down Chain of Craters Road from the Kilauea Visitor Center.
Meanwhile, webcams continue to show widespread lava breakouts along the June 27 lava flow within 5 miles of Puu Oo vent. Equipment at Puu Oo recorded weak inflation during the past day.
On Tuesday, Hawaii County Civil Defense issued its first eruption and lava flow update since suspending the daily breifing on March 28. Civil Defense said the recent rise in the lava lake level has “not resulted in any significant change or increased activity at Puu Oo.”
“The team at the USGS Hawaiian Volcano Observatory is maintaining close observations of all volcanic activity and the community will be kept informed of any changes in the level of volcanic threat,” Civil Defense said.
The U.S. Geological Survey Hawaiian Volcano Observatory on March 25 downgraded its alert level for Kilauea Volcano from a “warning” to a “watch.”