Explosive eruptions and noxious gas emissions at Kilauea Volcano in Hawaii this week have prompted scientists to work around the clock to understand what will happen next and how to keep the public out of harm's way.
Scientists are monitoring gas emissions and seismic activity at Kilauea, which on March 19, 2008 experienced its first explosive eruption since 1924. The volcano is also emitting sulfur dioxide at toxic levels.
At 2:58 a.m. H.s.t on Wednesday, March 19, 2008, a small explosion occurred at Halema‘uma‘u Crater at the summit of Kilauea Volcano in Hawai‘i Volcanoes National Park. This event was erroneously reported as an earthquake earlier this morning. The explosion scattered debris over an area of about 75 acres (30 hectares), covering a portion of Crater Rim Drive and damaging the Halema‘uma‘u overlook. No lava was erupted as part of the explosion, suggesting that the activity was driven by hydrothermal or gas sources.
In addition to damaging the overlook, explosive debris covers the trail to the overlook, the Halema‘uma‘u parking area, and the portion of Crater Rim Drive adjacent to the parking area. On Crater Rim Drive the debris was up to 2 centimeters in size, with the size and thickness of debris increasing toward the overlook. The largest observed block ejected during the explosion was about 1 cubic meter (35 cubic feet) and must have been propelled from the vent located more than 70 m (230 feet) below the crater rim. Small impact craters from 30 cm (1 foot) blocks are abundant in the Halema‘uma‘u overlook area. Rock debris also extends halfway across the floor of Halema‘uma‘u Crater. The debris is composed of rock fragments that were derived from the walls of Halema‘uma‘u Crater. No fresh lava was observed on the floor of Halema‘uma‘u or in the ejected debris.
At 2:55 am, the Hawaiian Volcano Observatory recorded a series of seismic events that may have been shallow, high-frequency earthquakes or minor explosions. The main explosion at 2:58 was associated with long period seismicity. Low frequency sound waves were also detected by the University of Hawai`i infrasound laboratory, operated by Dr. Milton Garces. These signals have persisted through this morning indicating continuing energetic release of gas from the vent in Halema‘uma‘u Crater.
The explosion produced a small crater along the east wall of Halema‘uma‘u that is about 20-30 meters (65-100 feet) in diameter. The crater occupies the area in which incandescence had been observed during the previous week. Sulfur dioxide emissions from the new explosion crater are still elevated, and sounds of rock breaking are frequent.
This is the first explosion in Halema`uma`u crater since 1924 and the first eruption of any kind in Kilauea caldera since September 1982.
Future explosive activity is possible and the Hawaiian Volcano Observatory continues to monitor the activity.
Sulfur dioxide emissions at the volcano's summit have increased to a rate that is likely to be hazardous for areas downwind of Halema'uma'u crater. Future explosions from Halema'uma'u Crater are possible.
"This historic activity has created new hazards that did not exist before -- explosive eruptions as well as toxic sulfur dioxide emissions -- in the middle of a national park," said U.S. Geological Survey Volcano Hazards Program Coordinator John Eichelberger.
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