Event Name : Makushin Mid-Holocene Tephras
|Start: 4980 (± 90 Years) || Years BP C-14 (raw) || |
|Lahar, debris-flow, or mudflow: ||
|Pyroclastic flow, surge, or nuee ardente: ||
From Beget and others (2000): "Following the caldera-forming eruptions, frequent but smaller events have occurred up to the present time (fig. 4 [in original text]). The most complete record of Makushin eruptions is found in the upper Makushin Valley, where at least 26 volcanic ash layers, some as much as 5 centimeters thick, are preserved in peat formed on the surface of the valley fill during the last 4,000 years. Several small pyroclastic flow and surge deposits found on the northeast, north, southeast, and west flanks of Makushin Volcano record eruptions that affected the volcano’s flanks up to 8 kilometers from the vent. Lahar and flood deposits, possibly produced by small eruptions, are present at low elevations in virtually all streams draining the volcano and can also be traced 8 to 10 kilometers downvalley from the vent."
From Bean (1999): "A stratigraphic section from a fan in Makushin Valley (Fig. 10.1 [in original text]) has preserved an excellent record of small eruptive events over the last ~5000 years. Section 96MAK03 preserves 29 prehistoric tephras above a peat dated at 4910+/-80 14C yr B.P. This is a minimum estimate on the number of eruptions because of varying wind directions, indistinguishable multiple fall layers, and erosion. It is unlikely that one section would preserve all erupted tephras. Also, the smallest magnitude eruptions are often not distinctly preserved in the geologic record."