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Nue??es ardentes of 22 November 1994 at Merapi volcano, Java, Indonesia

Journal of Volcanology and Geothermal Research

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Abstract

Nue??es ardentes associated with dome collapse on 22 November 1994, at Merapi volcano traveled to the south-southwest as far as 6.5 km, and collectively accumulated roughly 2.5-3 million cubic meters of deposits. The damaged area comprises 9.5 km2 and is covered by two nue??e ardente facies, a conventional "Merapi-type", valley-fill block-and-ash flow facies and a pyroclastic surge facies. The proximal deposits reflect the accumulation of dozens of nue??es ardentes, with many subsidiary flow units. The distal deposits are more simply organized, as only a few individual events reached to distances > 3.5 km. The stratigraphic relationships north of Turgo hill indicate that the surge deposits are a facies of particularly mobile nue??es ardentes that also deposited channeled block-and-ash flow facies. They further suggest that the surge facies beyond the channel margins correlate laterally with a finer-grained sublayer locally developed at the base of the block-and-ash flow facies. Eyewitness reports suggest that the emplacement of the block-and-ash flow facies in the distal part of the Boyong river may have followed, by a short time interval, the destruction and deposition of the surge facies at Turgo village. The stratigraphy is in accord with the eyewitness reports. The surge facies was emplaced by a dilute surge current, detached from the same dome-collapse nue??e ardente that, as a separate flow unit, subsequently emplaced the distal block-and-ash deposit in the Boyong valley. The detachment occurred at higher elevations, likely at or above the slope break at about 2000 m elevation. This flow separation enabled the surge current to shortcut over the landscape and to emplace its deposit even as the block-and-ash flow continued its tortuous southward movement in the Boyong channel. Dome-collapse nue??e ardente activity formed the bulk of the eruption, which was accompanied by virtually no significant vertical summit explosive activity. ?? 2000 Elsevier Science B.V. All rights reserved.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Nue??es ardentes of 22 November 1994 at Merapi volcano, Java, Indonesia
Series title:
Journal of Volcanology and Geothermal Research
Volume
100
Issue:
1-4
Year Published:
2000
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Journal of Volcanology and Geothermal Research
First page:
345
Last page:
361
Number of Pages:
17