Augustine Pyroclastic Flow West of Augustine Creek
Start: 1000 yBP ± 100 Years [1]
Stop: 710 yBP ± 50 Years [1]
Event Type: Not an eruption
Description: From Waitt and Beget (1996): "Between about 1000 and 700 yr B.P. (between tephra layers C and M) pyroclastic flows, pyroclastic surges, and lahars swept the west and south flanks."
"In a coastal gully 300 m west of Augustine Creek, a sandy pumiceous pyroclastic-flow deposit (unit CMp) 0-3 m thick underlies the M(?) tephra and overlies the thick, oxidized pumiceous pyroclastic-flow deposit of "southwest pyroclastic fan" (unit Hcpw). One site reveals two massive deposits-a lower one 13 m thick with gas-escape pipes and an upper one 4 m thick-separated by 20 cm of apparently fluvial deposit lacking a paleosol. These flows probably followed Augustine Creek when and spilled through a western swale. This unit, apparently scarcely eroded, pinches out about 0.5 km west of the creek: its overbank spillage was thus limited to the vicinity of present creek."
"During this prehistoric period numerous domes must have been emplaced at the summit, repeatedly renewing the source for catastrophic debris avalanches. Remnants of these older domes form the east and south sides of the present summit-dome complex. Below the summit area at least three domes were emplaced on the upper flanks, one on the south (Karnishak dome), two on the northwest (domes "I" and "H"). Another undated and nearly buried dome or lava flow diversifies the upper south flank."
"In a coastal gully 300 m west of Augustine Creek, a sandy pumiceous pyroclastic-flow deposit (unit CMp) 0-3 m thick underlies the M(?) tephra and overlies the thick, oxidized pumiceous pyroclastic-flow deposit of "southwest pyroclastic fan" (unit Hcpw). One site reveals two massive deposits-a lower one 13 m thick with gas-escape pipes and an upper one 4 m thick-separated by 20 cm of apparently fluvial deposit lacking a paleosol. These flows probably followed Augustine Creek when and spilled through a western swale. This unit, apparently scarcely eroded, pinches out about 0.5 km west of the creek: its overbank spillage was thus limited to the vicinity of present creek."
"During this prehistoric period numerous domes must have been emplaced at the summit, repeatedly renewing the source for catastrophic debris avalanches. Remnants of these older domes form the east and south sides of the present summit-dome complex. Below the summit area at least three domes were emplaced on the upper flanks, one on the south (Karnishak dome), two on the northwest (domes "I" and "H"). Another undated and nearly buried dome or lava flow diversifies the upper south flank."
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] 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.
map in GIF format 21 KB 
full-text PDF 2.6 MB
map sheet 295 MB! [3] 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.
full-text PDF 2.08 MB
map sheet plate 3.14 MB [4] Cyclic formation of debris avalanches at Mount St Augustine volcano, 1992
Beget, J. E., and Kienle, J., 1992, Cyclic formation of debris avalanches at Mount St Augustine volcano: Nature, v. 356, n. 6371, p. 701-704.Complete Eruption References
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.
map in GIF format 21 KB
full-text PDF 2.6 MB
map sheet 295 MB! 
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.
full-text PDF 2.08 MB
map sheet plate 3.14 MB 
Cyclic formation of debris avalanches at Mount St Augustine volcano, 1992
Beget, J. E., and Kienle, J., 1992, Cyclic formation of debris avalanches at Mount St Augustine volcano: Nature, v. 356, n. 6371, p. 701-704.
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/ .