Augustine

by Brandon Bray

Assignment 1:

The point of this assignment is to describe Mount Augustine's last significant eruption, and to then assign this eruption a VEI and a Mercalli eruption name.

Fig. 7: Aerial view of Augustine's ash plume from 30 January, 2006. Taken from: http://www.volcano.si.edu/world/volcano.cfm?vnum=1103-01-&volpage=var#bgvn_3101

Mount Augustine in Alaska last erupted in early 2006. Throughout January, February and March of 2006, Augustine began to erupt, with plumes of ash and gas reportedly reaching as high as 9 km. The volcano also had some small explosions, with pyroclastic flows and mudflows. Reports show that there were some volcanic bombs launched from the mountain, as is indicated by the sudden appearance of craters on the volcano's slope that were roughly the size of trucks. Seismic activity remained above background levels for some time after this eruptive event, however actual eruptions, including pyroclastic flows, ash falls, mudflows and avalanches, decreased significantly. By August 2006, seismic activity had returned to normal, background levels, and ash plumes and temperature fluctuations were almost nonexistent.

Given the height of the ash plume - ranging as high as 9 km - and the type of ejecta - including pyroclastic, lava and mud flows - I would classify this eruption as Vulcanian in style, with a VEI of 3.

Eruption statistics from: http://www.volcano.si.edu/world/volcano.cfm?vnum=1103-01-&volpage=var#bgvn_3101