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Kaguyak reported activity



Event Name : Kaguyak CFE

Start: 5800 (± 200 Years) Years BP C-14 (raw)

Tephrafall: BibCard BibCard
Pyroclastic flow, surge, or nuee ardente: BibCard BibCard BibCard
Caldera/crater: BibCard BibCard BibCard BibCard BibCard
Eruption Type:Explosive
MaxVEI: 5 BibCard
Eruption Product: dacite BibCard

Description: From Miller and Smith (1987): "Kaguyak crater is a small (2.6 km diameter), little-known, lake-filled, circular caldera in the northeast corner of the [Katmai National] park (Fig. 1 [in original text]). Nonwelded ash-flow tuffs are confined to within 7 km of the caldera and do not appear to have been particularly mobile. The ash flows filled previously glaciated valleys..."

From Fierstein (2007): "A dacitic Plinian eruption blanketed at least 120 km2 with a moderate-sized ignimbrite during the caldera-forming eruption at Kaguyak, 70 km NE of Mount Katmai. Although the accompanying coarse plinian fallout is not widely preserved (and may never have been widely dispersed), the coignimbrite ash elutriated during emplacement of the ignimbrite is a widespread marker bed in the region (see discussion of "Bright orange fine ash" [in original text]). Microprobe analyses of magnetites from this ejecta are distinctively low TiO2, and glass shards are distinctively low in K2O and high in CaO at 75.5-78.5% SiO2, which clearly distinguishes them from ejecta of all other Katmai volcanoes (Figs. 5, 13 [in original text]). Many radiocarbon dates from locations between Windy Creek and Kaguyak caldera constrain the collapse event to 5,800 14C years B.P."

"Eruption volumes are poorly constrained for this caldera-forming event due to patchy preservation and/or exposure...Deposits within 10 km of vent are all pumice falls, shed from (what was likely) a (sub)plinian column. Beyond 25 km from vent, the fallout is a fine-grained bright orange layer that is largely coignimbrite ash. Thickness data used in volume calculations (after Fierstein and Nathenson, 1992) yield an estimate of ~0.3 km3 within the moderately constrained 9-cm isopach and another 0.4 km3 within the less well constrained 3-cm isopach. Although distal ash distribution is poorly constrained, we draw tentative isopachs to 1.5 cm that include the well-correlated tephra on the Kenai Peninsula and the less well correlated tephra on Afognak Island and Kukak Bay (Fig. 1; see Section 8.1.3 [in original text]). This could add as much as 2.8 km3 to the fall volume, for a total tephra fallout volume of as much as ~3.5 km3 (~1.5 km3 DRE)."

The Global database on large magnitude explosive volcanic eruptions (LaMEVE; 2017) reports a magnitude of 6.500, bulk eruptive volume of 3.900cubic km and a dense rock equivalent eruptive volume of 1.200 cubic km for the eruption.

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Page modified: March 30, 2017 14:36
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