5 comments on “Great Sitkin – flank collapse in the Aleutians

  1. Great post, on a volcano we don’t hear too much about (like most Aleutian ones, to be fair). Has anyone offered any ideas on the relationship between the present volcanism and the Eocene volcanics of the island’s ‘basement’? The idea of a volcanic centre sitting in the same spot for 33 million years plus,is a bit hard to swallow; but OTOH so is the idea of a subduction arc stationary for that long – which seems to have been the case?

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    • Howdy Michael –

      Hope all is well with you and yours. The Preliminary Hazard Assessment traced the Sand Bay Volcanics as far back as the Eocene, meaning 33 MY is the youngest. They mentioned Cretaceous as a possible starting point which scared me. I was uncomfortable going that far as there didn’t seem to be enough stuff on the floor of the Bering Sea north of Great Sitkin to support that. Wondering if the longevity in this part of the Aleutians is connected to the subduction changing to transform as you travel west along the trench. Seems to me that in the western portions of volcanic activity will be less intense and somewhat longer lived, though this is all arm waving at this point. Cheers –

      The

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    • Howdy Michael – Thanks for the comment and question. Forced me to revisit the actual documentation. The actual verbiage was ‘late Tertiary” which is far more believable for a volcanic island on a subduction trench. Appears I conflated a paper about the Aleutian Trench with the hazard assessment for Great Sitkin. Thanks for the push. Correction is posted and post is updated. Cheers –

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