Geologists redraw map of volcanic his...

Geologists redraw map of volcanic history in Southeast Alaska

There are 2 comments on the Anchorage Daily News story from May 31, 2013, titled Geologists redraw map of volcanic history in Southeast Alaska. In it, Anchorage Daily News reports that:

Geologists with the U.S. Forest Service and the U.S. Geological Survey have spent recent years taking a close look at the volcanic history of Southeast Alaska and have added a dozen volcanoes to the map, as well as reclassifying many already known volcanic vents and lava flows.

Join the discussion below, or Read more at Anchorage Daily News.

Since: Feb 08


#1 May 31, 2013
Japan Has Destroyed Volcanoes not only in Japan but also in US

Japan is never a democratic nation.

When the government destroys volcanoes, we know that much more evil things have been done by the government against its own people.

“Geologist [I'm Climate Change]”

Since: Mar 07

formerly Nuneaton

#2 Jun 3, 2013
Nice article.

The interesting bit is that SE. Alaska is a backarc basin with a megathrust bounded W. margin with extremely oblique convergence with the Pacific plate. The magma is primary imported from magma discs at the base of the crust derived from partial melting of the descending Pacific plate. The reason why the volcanoes are scattered is because of the long interval time between Rebound/long duration Mercalli X (r/lx) quakes which relax the overlying plate and jog the entire Canada/SE Alaska backarc basin SE... AND the oblique convergence which jogs the forearc and arc NE. into the Wrangell forearc and splits the arc into segments with a very variable stress field which pops up volcanoes in different places each time.

For the record the oblique convergence produced a thrust quake @ Haider Gwaii (Canada) earlier last year (small tsunami).

The next BIG tsunami will be nucleated @ the wrangell arc and spread SE down the backarc basin so keep watching that space for details of timing. As a result of compression the mid to base crustal magma filled fractures will be squeezed flat @ the Wrangell volcanic field before r/lx occurs. As Mt.Wrangell is still active he r/lx & bloody great big tsunami is probably a while away.

Info on volcanism @ the Wrangell volcanoes & individual volcano eruptive behaviour in Simkin et al format should be available @ the Smithsonian institution "Global volcanism program website" (last seen in April).

Have a nice day: Ag

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