13 comments on “Volcanoes of Peru 3: Huaynaputina – Catastrophe in 1600

  1. Great post, Granyia, and a fascinating (if virtually unknown) volcano. What struck me after reading it was the more general peculiarity about Andean volcanoes, namely the ability to produce paroxysmal high-volume explosive eruptions WITHOUT generating caldera collapse. Huaynaputina, Lascar, and maybe also Quizapu/Cerro Azul in the 20th century (another half-forgotten eruption that deserves a second look IMO). Any thoughts?

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    • I can only give you my thoughts in regard of Huaynaputina at the moment. Of the 30 km3 of tephra produced, only 11 km3 were magma (the rest was the mountain itself). That would be a “hole” of 3x4x1 km, which for sure is a lot, but perhaps not enough for a caldera forming event with highly viscous magmas.

      The ejecta came from two different chambers at distinct depths, ~6 and ~15 km (but it seems not to be known, which one produced more, and if they were at about the same location). That divides the amount of magma removed from one place, if it was 50/50, to only abt. 5.5 km3. If most of it came from the deeper source, it may have been unlikely to have caused a caldera anyways.

      The erupted lavas have been rich in silica (as far as I can see for all stages of the eruption) and magma mixing from the two different chambers may have taken place. Both accounts for the high explosivity. It may also be one reason for not forming a caldera – and this is just my guess, I’d have to read up – I think that eruptions with very liquid lavas are more likely to cause a caldera than with thick viscous ones. Liquid stuff can be ejected much faster, and the “void”, or re-filled, chamber below the roof must be much softer than with silica rich magmas, thus allowing the roof to sink, or break in easier. — But I am not an expert, perhaps a more geologically trained person could say if this is all rubbish 🙂

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    • …and Fuego erupting in the distance. Nice, thank you! Fuego should have risen to the occasion and done something more spectacular, though! 😉

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  2. There are two things that really amazed me when I researched the article. The first is the fact that from the Greenland ice core acidity profile it was calculated that 16 to 32 Mt of sulfur were erupted (causing a spike greater than that from Krakatoa), while petrological estimates say that the erupted magma itself did not contain more than 2-4 Mt, which is a mere 12,5%. The rest must have been “hot air”, vapours from hydrothermal output. – So, where does that huge amount of Sulfur gases come from? Does not the hydrthermal system transport only ingredients dissolved out of the near surface magma that it encounters? If it is pure gases, they certainly must have come from degassing of magma, thus also having been in it before?

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  3. The second is rather interesting than unbelievable: “Historical accounts also report that about one meter fell north and west of the city of Arequipa. Today, one-centimeter-thick layers can be found no farther than 200 km northwest of the eruption, not 800-1000 km, and the deposits in the vicinity of Arequipa are only 10 cm thick at best, not one meter thick.”
    So, where are the 90% of tephra gone? Erosion, yes, further distributed by wind and rain. But, 400 years are no geological time. It is hard to imagine that ~4 km3 deposits (of the total DRE volume of 4.6–4.95 km3) were eroded from such a relatively small area in such a short time.

    These two results should probably have played an enormous role in the interpretation of both ice core measurements (my comment above) and tephrochronological studies. If you have a big sulfur spike in the ice core records, it does not necessarily mean a huge eruption has taken place somewhere at that time. And if you have a small layer of ash it does not necessarily mean that no huge eruption has occured.

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  4. I need to ask two probably real amateur questions. From yesterday’s report on Ubinas: “Ubinas has been emitting ash continuously and had numerous exhalations and explosions.” You find that mostly (or only?) in spanish reports, in English reports you see phreatic explosions and strombolian/vulcanian eruptions. So, what exactly are exhalations? (As far as I know Ubinas does not have either strombolian or vulcanian activity).

    Further down it says: “Moreover, in the last 24 hours it has been observed some drumbeats type earthquakes although weak, which may indicate rise of magma with lower debit”. Is that what GL in VC called chugging, that showed in spectrograms as regular vertical lines through all frequencies?

    (http://ovs.igp.gob.pe/drupal/?q=node/42 Report 2015-17)

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