Akutan Broad Bight Valley Lahars
Start: 1611 yBP [1]
Event Type: Not an eruption
- Lahar, debris-flow, or mudflow [1]
Description: From Waythomas (1999): "Broad Bight valley is a wide glacial valley on the south side of Akutan Island, southeast of the caldera (Fig. 1 [in original text])."
"Lahar deposits in the middle part of Broad Bight valley (sections 58, 70, 71, Fig. 12 [in original text]) form a downstream thinning fan that covers the valley floor to a depth of at least 2 m. These lahar-runout deposits are distinctly finer grained (largest clasts are pebble size) and contain a greater percentage of fines (silt+clay) than their upstream counterparts. At section 87 (Fig. 12 [in original text]) lahar runout deposits overlie the Akutan tephra. Indicating that most, if not all, of the lahar deposits in Broad Bight valley are younger than the tephra."
"Lahar deposits in the middle part of Broad Bight valley (sections 58, 70, 71, Fig. 12 [in original text]) form a downstream thinning fan that covers the valley floor to a depth of at least 2 m. These lahar-runout deposits are distinctly finer grained (largest clasts are pebble size) and contain a greater percentage of fines (silt+clay) than their upstream counterparts. At section 87 (Fig. 12 [in original text]) lahar runout deposits overlie the Akutan tephra. Indicating that most, if not all, of the lahar deposits in Broad Bight valley are younger than the tephra."
References Cited
[1] Stratigraphic framework of Holocene volcaniclastic deposits, Akutan Volcano, east-central Aleutian Islands, Alaska, 1999
Waythomas, C. F., 1999, Stratigraphic framework of Holocene volcaniclastic deposits, Akutan Volcano, east-central Aleutian Islands, Alaska: Bulletin of Volcanology, v. 61, n. 3, p. 141-161.Complete Eruption References
Stratigraphic framework of Holocene volcaniclastic deposits, Akutan Volcano, east-central Aleutian Islands, Alaska, 1999
Waythomas, C. F., 1999, Stratigraphic framework of Holocene volcaniclastic deposits, Akutan Volcano, east-central Aleutian Islands, Alaska: Bulletin of Volcanology, v. 61, n. 3, p. 141-161.
