Augustine Northeast Bench Debris Avalanche or Lahar
Start: 1725 yBP ± 25 Years [1]
Stop: 1470 yBP ± 160 Years [1]
Event Type: Not an eruption
- Debris-avalanche, volcanic avalanche, or landslide [1]
Description: From Waitt and Beget (1996): "A bouldery gravel diamict (unit JH) containing angular porphyritic andesite stones as large as 4 m lies outside (north of) the levee that delineates the north side of main body of Northeast Point debris-avalancbe deposit (unit IHa). The seaward part of this unit north of the levee is relatively nonhummocky and called here Northeast Bench. By this morphology the unit underlying the bench is interpreted as a lahar deposit (unit IHl). But more than 200 m back from the sea cliff the area outside levee is nearly as hummicky as that south of the levee and this is also mapped with unit IHa. Both map units (units IHl and IHa) are overlain by a tephra sequence with tephra H at its base. The flattish seaward-sloping part of this area delineating the bench may be a laharic phase that issued from the debris avalanche."
"Sandy gravel lacking large blocks underlies H? tephra atop the Pleistocene landslide block *Unit Pl) on south side of island. It may contemporaneous with Northeast Bench lahar (?) deposit."
"Sandy gravel lacking large blocks underlies H? tephra atop the Pleistocene landslide block *Unit Pl) on south side of island. It may contemporaneous with Northeast Bench lahar (?) deposit."
References Cited
[1] Volcanic processes and geology of Augustine Volcano, Alaska, 2009
Waitt, R.B., and Beget, J.E., 2009, Volcanic processes and geology of Augustine Volcano, Alaska: U.S. Geological Survey Professional Paper 1762, 78 p., 2 plates, scale 1:25,000, available at http://pubs.usgs.gov/pp/1762/ .[2] Preliminary volcano-hazard assessment for Augustine Volcano, Alaska, 1998
Waythomas, C. F., and Waitt, R. B., 1998, Preliminary volcano-hazard assessment for Augustine Volcano, Alaska: U.S. Geological Survey Open-File Report 98-0106, 39 p., 1 plate, scale unknown.

[3] Provisional geologic map of Augustine Volcano, Alaska, 1996
Waitt, R. B., and Beget, J. E., 1996, Provisional geologic map of Augustine Volcano, Alaska: U.S. Geological Survey Open-File Report 96-0516, 44 p., 1 plate, scale 1:25,000.


Complete Eruption References
Preliminary volcano-hazard assessment for Augustine Volcano, Alaska, 1998
Waythomas, C. F., and Waitt, R. B., 1998, Preliminary volcano-hazard assessment for Augustine Volcano, Alaska: U.S. Geological Survey Open-File Report 98-0106, 39 p., 1 plate, scale unknown.



Provisional geologic map of Augustine Volcano, Alaska, 1996
Waitt, R. B., and Beget, J. E., 1996, Provisional geologic map of Augustine Volcano, Alaska: U.S. Geological Survey Open-File Report 96-0516, 44 p., 1 plate, scale 1:25,000.




Volcanic processes and geology of Augustine Volcano, Alaska, 2009
Waitt, R.B., and Beget, J.E., 2009, Volcanic processes and geology of Augustine Volcano, Alaska: U.S. Geological Survey Professional Paper 1762, 78 p., 2 plates, scale 1:25,000, available at http://pubs.usgs.gov/pp/1762/ .