Halemaumau Crater

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After a 2008 explosive eruption, a sulfur dioxide plume emanates from a vent in Halemaʻumaʻu crater.

Map of Kilauea Crater April 2008.

Halemaʻumaʻu crater is a pit crater located within the much larger summit caldera, of Kīlauea, Hawaii Volcanoes National Park. The roughly circular crater floor is 770 metres (2,530 ft) x 900 metres (2,950 ft) and is 83 metres (270 ft) below the floor of Kīlauea caldera. Halemaʻumaʻu is home to Pele, Goddess of Hawaiian Volcanoes, according to the traditions of the native people.^[1]^[2]

1 Eruptive history
2 2008 eruption episodes
- 2.1 March eruption episode
- 2.2 April eruption episode
3 References

[edit] Eruptive history

William Ellis, a missionary and amateur ethnographer and geologist, published the first description of Halemaʻumaʻu as it appeared in 1823.^[3]

Astonishment and awe for some moments rendered us mute, and like statues, we stood fixed to the spot, with our eyes riveted on the abyss below. Immediately before us yawned an immense gulf, in the form of a crescent, about two miles in length, from north-east to south-west, nearly a mile in width, and apparently 800 feet deep. The bottom was covered with lava, and the south-west and northern parts of it were one vast flood of burning matter, in a state of terrific ebullition, rolling to and fro its “fiery surge” and flaming billows.

In 1866 Mark Twain, an American humorist, satirist, lecturer and writer hiked to the Caldera floor.^[4]

Here's his account of the lake of molten lava, which he found there:

It was like gazing at the sun at noon-day, except that the glare was not quite so white. At unequal distances all around the shores of the lake were nearly white-hot chimneys or hollow drums of lava, four or five feet high, and up through them were bursting gorgeous sprays of lava-gouts and gem spangles, some white, some red and some golden--a ceaseless bombardment, and one that fascinated the eye with its unapproachable splendor. The mere distant jets, sparkling up through an intervening gossamer veil of vapor, seemed miles away; and the further the curving ranks of fiery fountains receded, the more fairy-like and beautiful they appeared.

The level of the lava lake varied over the decades and at times was only 30 metres (100 ft) below the crater rim. In 1924,^[5] explosive eruptions sent dust high into the atmosphere and doubled the diameter of the crater. Fractures allowed the lava lake to drain to the east until its surface was 366 metres (1,200 ft) below the caldera floor. Subsequent eruptions have mostly refilled the crater. Most of the current crater floor was formed in 1974.^[2] A 1982 eruption covered a small portion of the northeastern crater floor.^[6]

[edit] 2008 eruption episodes

[edit] March eruption episode

Before and after comparison of the new gas vent. The crater overlook is circled for reference.

An April 3, 2008 aerial view of the March 19 explosion site.

Crater activity began to increase when between March 10 and March 14, 2008 gas began to vent from the east wall fumarole directly below the Crater Overlook;^[7] however the gas event was only a prelude when in the wee hours (02:58 am HST) of March 19, 2008 HVO personnel thought they were experiencing seismic events, but sunrise revealed a 20–30 metre (65–100 foot) diameter hole blown in the side where the vent once was; scattering debris and spatter across 0.30 square kilometres (74 acres) and damaging the Crater Overlook. Pieces as large as 20 millimetres (1 in) were found on Crater Rim Drive while 0.3 metres (1 ft) blocks hit the crater overlook area.^[8] This was the first explosive eruption of Halemaʻumaʻu Crater since 1924, and the first lava eruption from the crater since 1982.^[9]

Sulfur dioxide gas emissions increased rapidly at the beginning of the episode. On March 13, HVO recorded a rate of 2,000 tons/day, the highest rate since measurements began in 1979. A concentration of over 40 ppm on Crater Rim Drive was measured, prompting alerts and other public safety measures.^[10]^[7] Halemaʻumaʻu crater continued to intermittently emit high levels of volcanic gases, ash, spatter, Pele's Tears,and Pele's Hair until the second episode.^[11]

[edit] April eruption episode

Before and after view of second explosion on April 9.

At night, an incandescent glow illuminates the venting gas plume on April 14.

This episode began with an explosion on the night of April 9, 2008 that widened the hole by an additional 5–10 metres (15–30 feet), ejected debris over some 60 metres (200 ft) and further damaged the overlook as well as scientific monitoring instruments.^[12]

In response to the second episode, scientists and local government officials on April 9, 2008 ordered hundreds of people to evacuate from Hawaii Volcanoes National Park and nearby villages because the sulfur dioxide concentration levels had reached a critical level and a hazardous vog plume extended downwind from the crater. The evacuation lasted two days.^[10]

As of April 23, 2008, the eruption episode continued.

Other than the above described debris ejected by both explosion events, no erupting or fountaining of lava has occurred in the crater, unlike the concurrent activity on the Eastern Rift Zone around Pu'u O'O.
Night time viewing of the crater's webcam reveals an incandescent illumination of the venting gases, leading scientists to suggest in their daily reports that molten lava may reside at shallow depth within the new vent; ^[13].
The overlook is closed and frequent closures of Crater Rim Drive are expected. Visitors may view the crater from the relatively safe locations of the Hawaiian Volcano Observatory and Volcano House.

The United States Geological Survey's Hawaiian Volcano Observatory publishes frequent eruption summaries, press releases, maps, and other data, as well as provides both real- and near real-time hazard data and panoramic Internet web camera views of events.^[14]^[15]

May 5, 2008 aerial image into Halema'uma'u gas vent, revealing dull orange glow from incandescent activity. Reports still reflect lava present at some depth but not evident as of this date.