Pumice and other pyroclastic deposits in Mount Rainier National Park, Washington

Abstract

typically are stained to fairly strong brown or reddish brown; interbedded lithic ash deposits have relatively neutral but somewhat darker brownish-gray colors. Ash beds from other volcanoes (note beds marked 0, set Y, set P, and WI characteristically are lighter in color than the locally derived deposits that enclose them. S1te is in an alpine meadow near Williwakas Glacier on the southeast flank of Mount Ramier .

Sources of uncertainty in the Mazama isopachs and the implications for interpreting distal tephra deposits from large magnitude eruptions

“…For the published isopachs (b, c) some thicknesses are not clearly stated in the relevant thesis and have been marked as 'ND'. e Minimum extent maps of the Mazama tephra from (1) Mullineaux (1974), (2) Westgate and Gorton (1981) and 3Egan et al 2015Another source of variability in the bulk deposit volume estimates relates to the inclusion or exclusion of the ignimbrite volume (Table 1). Early work by Williams (1942) mapped the extent of the ignimbrite ('glowing avalanches') and estimated a bulk ignimbrite volume~29 km 3 , which he included in his bulk erupted volume (total~44 km 3 ).…”

“…The amalgamation of > 250 Mazama tephra occurrences highlights the wide range of disciplines that make use of the tephra layer from volcanology (Westgate and Dreimanis 1967;Mullineaux 1974) to archaeology (Kittleman 1973; Combining distal and proximal (Young 1990) isopach data McFarland 1989). The multidisciplinary use of the Mazama tephra has resulted in different methods of data collection and variable data quality.…”

A probabilistic assessment of tephra-fall hazards at Hanford, Washington, from a future eruption of Mount St. Helens

“…At 8 kilometers from the vent, for example, the thickest post-4 ka tephra deposit from MSH (Yn of table 2) is about 2 meters (m) thick (Mullineaux, 1986;Carey and others, 1995). For comparison, at 7 km distance from Rainier, the thickest post-4 ka Rainier deposit (the C tephra) is about 30 centimeters (cm) (Mullineaux, 1974); and at 6 km from Mount Adams, the thickest layer (layer 23 of Hildreth and Fierstein [1997]) is less than 10 cm. At Mount Hood, the only post-4 ka tephra deposits were produced when domes growing south of the summit collapsed and avalanched down the steep south flank, releasing clouds of debris.…”