Hello Michael - I have not studied the sulfur spike in question. Herbert's crater does seem young, and it does have hot fumaroles, suggesting youthfulness. However, I don't see a compelling reason to tie the unidentified eruption to Herbert - we just don't know very much about Herbert (or many other Aleutian volcanoes, for that matter.) Thanks, cheryl -------- Michael Firth wrote: Hi, I have today been involved in a discussion on the Volcano Cafe blog about an eruption with an unidentified source that produced a significant sulphur spike that happened around 1601 CE, as a "dual" climate effect with the large eruption of Huaynaputina in Peru in 1600 (similar to the "missing" 1808/09 eruption combined with Tambora). It is believed to have been from the northern hemisphere, with a possible location being in the Aleutians. A suggestion was made that it could have been from the eruption that formed Herbert's caldera, because of its appearance which suggests it was quite recent, and the fact there's no data on its eruptive history. Is it realistically possible that Herbert could potentially be the source of this eruption? -- Cheryl Cameron Geologist, Alaska Volcano Observatory Alaska Division of Geological & Geophysical Surveys voice: 907-451-5012 fax: 907-451-5050