Phreatic eruptions of Ruapehu: April 1975

Nairn, I. A.; Wood, C. P.; Hewson, Chad

doi:10.1080/00288306.1979.10424215

Cited by 84 publications

(52 citation statements)

References 11 publications

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“…In both LH4c and the 1975 lahar there was a sharp drop in peak discharge between 42 and 56.5 km from the source. The river becomes more 1927Stillwell et al 1954Stillwell et al 1954Stillwell et al 1954O'Shea 1954Hodgson 1993Paterson 1976Houghton et al 1987Houghton et al 1987Healy et al 1978Houghton et al 1987Healy et al 1978Houghton et al 1987Healy et al 1978Houghton et al 1987Healy et al 1978Houghton et al 1987Healy et al 1978Houghton et al 1987Healy et al 1978Houghton et al 1987Healy et al 1978Houghton et al 1987Healy et al 1978Paterson 1976Nairn et al 1979Houghton et al 1987Nairn et. al.…”

Section: Peak Dischargementioning

confidence: 99%

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1995 Ruapehu lahars in relation to the late Holocene lahars of Whangaehu River, New Zealand

Cronin

Hodgson

Neall

et al. 1997

New Zealand Journal of Geology and Geophysics

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Observations of active flows, their deposits, and the effects of lahars generated during the 1995 eruptions of Ruapehu are compared to those of the last 2000 years. The 1995 lahars were generated by similar mechanisms, and had similar volumes and flow rheologies, to those of the last 135 years. However, the large number of lahars in the 1995 sequence and the eventual emptying of the entire Crater Lake on Mt Ruapehu by lahars is distinctive in the context of the historic record. The 1953 and 1975 lahars, although of smaller total volume than the largest 1995 lahar, had higher peak discharges and consequently greater effects on life and property within 57 km from the source. This implies that failure of a lake dam is the most efficient mechanism for generating a fast lahar with high peak discharge, and that eruptions through Crater Lake are more efficient at generating a lahar with high peak discharge when the lake is full.The scant 1995 lahar deposits preserved indicate that the geological record of lahars is likely to be incomplete and biased to events of greatest magnitude. Given this limitation, lahars which formed deposits of the prehistoric (>135 years old) Onetapu Formation were of larger magnitude in all respects, and often more concentrated with sediment, than those of the last 140 years (including 1995). In order to generate such events, catastrophic total emptying of Crater Lake is required. Alternatively, some of the events may have been the result of small flank collapses on the eastern slopes of Ruapehu. These larger events are less frequent than small eruption-triggered lahars on Ruapehu, but they may be preceded by little or no warning. Future lahar hazard mitigation strategies in the Whangaehu River should begin with improving the detection and early warning of such flows. G96042

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Section: Peak Dischargementioning

confidence: 99%

“…Since A.D. 1861,19 lahars have been recorded, including one in 1953 which resulted in the loss of 151 lives when a railway bridge at Tangiwai was destroyed by a lahar just before a passenger train was crossing (O'Shea 1954;Nairn et al 1979;Hodgson 1993). From 1850 yr B.P.…”

Section: Introductionmentioning

confidence: 99%

1995 Ruapehu lahars in relation to the late Holocene lahars of Whangaehu River, New Zealand

Cronin

Hodgson

Neall

et al. 1997

New Zealand Journal of Geology and Geophysics

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“…The resultant perlite resembles material of the rhyolitic bombs ejected by the eruption. 'Pumice' of similar origin, generated by heating of old rocks, was reported from eruptions of Ruapehu volcano in 1975 (Nairn et al, 1979) and from a submarine eruption off Izu Peninsula, Japan, in 1989 (Yamamoto et al, 1991). Blocks of greenish hydrothermally altered breccia are dominant among the other accidental clasts ejected by the eruption.…”

Section: Compositionmentioning

confidence: 99%

Eruptive Process, Effects and Deposits of the 1996 and the Ancient Basaltic Phreatomagmatic Eruptions in Karymskoye Lake, Kamchatka, Russia

Belousov

Belousova

2001

Volcaniclastic Sedimentation in Lacustrine Settings

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On 2-3 January 1996 an explosive eruption discharging = l0 6 kgs -1 of basaltic magma occurred in Karymskoye lake at an initial water depth of ~ 50 m. Characteristics of the deposits together with analyses of a videotape of several explosions have allowed us to model the eruptive events. Initial vent-clearing phreatic explosions ejected blocks of country rocks (up to 3 m diameter) to distances of up to 1.3 km. Then followed 10-20 h of phreatomagmatic Surtseyan activity (100-200 outbursts of water-gas-pyroclastic mixtures to heights of up to 1 km, with initial velocities of 110 m s -1 |. The eruption slugs collapsed back into the lake and produced base surges (runout up to 1.3 km; average velocity 12.5 m s -1 ). The convective eruption plume rose to a height of 3 km and deposited a thin distal fall deposit. The eruption ended with the ejection of scoria-crust bombs (specific basaltic bombs with dense core and scoriaceous crust).Pyroclasts of the eruption are mostly poorly to moderately vesicular juvenile basaltic particles shaped by a combination of magmatic vesiculation and magma-water interaction. Ninety-five percent of the products (0.047 km 3 ) formed an underwater tuff ring composed of parallel layers of moderately to poorly sorted lapilli ash and ash lapilli (Md -3.9 to 0.6 phi; sorting 1.5-3.2 phi), each 10-60 cm thick. They were deposited by water-rich base surges that originated from Surtseyan type eruption bursts. The most widespread hazards of the eruption were tsunamis and lahars. At distances < 1.3 km from the crater, base surges and ballistic clasts were very destructive.Eruptive activity in the lake before 1996 included two eruptions at c. 4800 14 C yr BP. The first left deposits similar to those of the 1996 eruption and thus is interpreted as a Surtseyan eruption that occurred at the same water depth as in 1996. The second of the 4800 l4 C yr BP eruptions deposited extensive cross-laminated base-surge deposits and is interpreted to have occurred in very shallow water.

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“…The fan sediments have been deposited by lahar events that are channelled down the upper part of Whangaehu River and avulse their courses on the relatively unconfmed lower ring plain ). This route has been the major path for Ruapehu lahars in historic times (e.g., 1953,1969, and 1975Gregg 1960;Nairn etal. 1979 Table 1; lahar deposit nomenclature from text.…”

Section: Present Channel Geographymentioning

confidence: 99%

“…This suggests that some lahars may have overflowed into the Upper Waikato Stream in the recent geologic past. Of the northeastern Ruapehu streams, the Mangatoetoenui is the only channel to have a historic record of lahars (Nairn et al 1979), including at least one lahar in the 1995 eruptive sequence.…”

Section: Present Channel Geographymentioning

confidence: 99%

A late Quaternary stratigraphic framework for the northeastern Ruapehu and eastern Tongariro ring plains, New Zealand

Cronin

Neall

1997

New Zealand Journal of Geology and Geophysics

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The northeastern Ruapehu and eastern Tongariro ring plains record a complex sequence of episodic lahar sedimentation. Andesitic and rhyolitic tephrostratigraphy reveals 15 lahar episodes in the northeastern Ruapehu ringplain record ranging in age from >65 to 5 ka, and five in the Tongariro ring-plain record ranging in age from >23 to 14 ka. The most voluminous and widespread lahar deposition occurred during cool and stormy climatic periods equivalent in age to marine δ 18 O Stages 2 and 4. In these periods, accelerated physical weathering on the volcanoes supplied erosion debris, while large areas of snow and ice acted as sources of water to form lahars triggered by a variety of mechanisms. Lahar distribution after c. 22.5 ka was affected by two landform changes in the area at about this time. First, a large lava flow was emplaced along the boundary between Ruapehu and Tongariro ring plains shortly before 22.5 ka, effectively separating the two ring plains since. Second, Last Glacial moraines along the Whangaehu and Mangatoetoenui Rivers have blocked direct drainage from the Ruapehu summit region to a large sector of the northeastern ring plain, including the Upper Waikato Stream, formerly an important lahar path. These moraines have directed subsequent lahars (after c. 15 ka) along their current routes (active in 1995) in the Whangaehu and Mangatoetoenui catchments. Lahar deposition in the study area during this time is linked to large, explosive andesitic eruptions impacting on catchments where retreating glaciers provided water for lahar generation.

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Phreatic eruptions of Ruapehu: April 1975

Cited by 84 publications

References 11 publications

1995 Ruapehu lahars in relation to the late Holocene lahars of Whangaehu River, New Zealand

1995 Ruapehu lahars in relation to the late Holocene lahars of Whangaehu River, New Zealand

Eruptive Process, Effects and Deposits of the 1996 and the Ancient Basaltic Phreatomagmatic Eruptions in Karymskoye Lake, Kamchatka, Russia

A late Quaternary stratigraphic framework for the northeastern Ruapehu and eastern Tongariro ring plains, New Zealand

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