Event Name : Emmons Gap Welded Tuff
|Start: 123000 || Years BP Ar/Ar || |
|Pyroclastic flow, surge, or nuee ardente: ||
|MaxVEI: ||4 ||
|Eruption Product: || other ||
From Waythomas and others (2006): "Major Plinian/ultra-Plinian eruption. Extensive ignimbrite sheets."
"Major explosive events with high column of ash and pyroclastic debris. Extensive ash dispersal and formation of mobile and far traveling pyroclastic flows."
"Eruptive product studies associated with caldera formation date the major eruptions around 294,000, 234,000, 123,000, 100,000, 30-50,000, and 26,000 years ago. Each of these eruptions produced relatively extensive pyroclastic-flow deposits of dacite to rhyolite composition hot enough to weld when deposited and form the welded tuff units shown in figures 7 and 8 [in original text]. Some of the welded tuffs show evidence of secondary flowage (rheomorphic tuffs) as far as 35 km from their source calderas (fig.8 [in original text]). Rheomorphic welded tuffs are unique to the Emmons Lake volcanic center and are found nowhere else in the Aleutian arc. The welded tuffs crop out in areas southeast and northeast of the caldera complex where they flowed into and filled preexisting valleys and ancestral drainages."
The Global database on large magnitude explosive volcanic eruptions (LaMEVE; 2017) reports a magnitude of 4, bulk eruptive volume of 0.10 cubic km and a dense rock equivalent eruptive volume of 0.040 cubic km for the eruption.