I am just curious to know whether postglacial rebound and crustal doming can occur in a volcano, particularly if it were to have been previously covered by ice? Furthermore can fracture formation and hydraulic conductivity also be incorporated into this based on;
Gudmundsson (1999) 'Postglacial crustal doming, stresses and fracture formation
with application to Norway' Tectonophysics.
I am curious as I would like to put this towards a cause for increased phreatic activity on Volcanic edifices as a potential hazard in the case of future climate change and volcanic activity.
Anyone think this maybe possible?
Is there a record of increased volcanic activity as we emerged from the last major period of glacial activity circa 12,000 years ago ? Or with Dansgaard-Oeschger cyclicity? That should have occurred if your hypothesis is correct. I also suppose this depends on the rates of melting and isostatic rebound. The ice melts much faster than Earth rebounds. What is the time delay and what factors dominate? I suspect there must be a link, and think this is a wonderful topic for further research. Especially as increased volcanic activity (perhaps Antarctica) should accelerate the rate at which ice sheets decay, - by the direct melting of ice, but even more by the lubricating effect of this on internal ice movement... not to mention impact of extensive ash fall. Not much help... but I hope lots of encouragement!
Dear David,
Thank you very much and indeed your answer has been encouraging, to be honest I didn't have a site or specific volcano in mind I was just wondering if the theory seemed logical, perhaps this is an areas of research I maybe able to pursue in the future
Kind regards,
Stephanie
Interesting idea, but as David suggested, the differential rates need to be considered. I don't have the answers, but here are some questions: How does faulting or dilation from isostatic readjustment react in an environment of hot, plastic rock in an active volcanic area? Is the rock plastic there at the depths affected? If it is not, then will the faults or dilated areas act as a conduit for eruption and/or fluid infiltration to/from surface, or will they fill with magma and cool at subsurface depths?
Just a thought, you may want to look at the active volcanic areas around the world that currently or recently had ice/glacial coverage - Iceland, Yellowstone, Kamchatka, Antarctica, etc. to see what processes have occurred.
Not just ice cover per se is involved, but related meltwater as well. Looking at Yellowstone as an example of an active volcanic region during the last glaciation, there are hydrothermal explosion craters (e.g. Pocket Basin) from effects of hot rock and meltwater interaction - although I would doubt that isostatic adjustment had a role there, meltwater/glacial lakes are another factor to consider in looking at the problem.
To David Kitchen
There is a relationship between the planets surface temperatures and
the formation of ice, or the melting of ice, and ocean levels, and the
elevation of the atmosphere in comparison to the continents.
If the ice melts off the continents, and fills the oceans, the atmosphere
move upward, while the continents move downward relative to sea
level, with the result being global warming at all altitudes over land.
Since he Lapse rate is about 3.5 F per 1,000 increase in elevation,
the global sea level rise of about 400 feet gave a rough value of
a temperature rise of about 0.4 ( 3.5 ) = 1.4 F solely from a change
is global land elevation. The actual value was higher due to other
combined effects like change in albedo, change in the surface area of
the oceans, reduction in the surface area of the land, change in
ocean circulation patterns, and several more.
As for change in the rate of volcano output, it would be required to
see if there is a change in magma release at numerous locations
world wide, not just in Iceland. For example, did the Volcanoes that
rim the Pacific Change frequency of eruptions , or in Indonesia,
or Hawaii, or Italy ?, or was the change only associated with Iceland ?
I suspect that the increase in the production of volcanic eruptions
in Iceland stems from the fact that Iceland is over the Mid-Atlantic
Spreading Ridge, and an increase in ocean depth limits the rate
of release, and height that magma can rise in the fissures when
the oceans are deeper. The result then will be that since
Iceland has no water depth holding down or cooling the rising magma,
and only a column of air to hold down the magma, the magma rises far
higher in elevation, where it is not vertically confined by the ocean
overburden pressures. Iceland is just the weakest spot in a
connected system of rising magma along the Spreading Ridge,
so the magma flow moves to the weakest spot to be released.
Hi Stephie,
in my opinion, it can be just a release of the growen mount, so be careful to obtain data on regional movements. We need regional measuremnt data. Good Luck! :))
Thank you to you all for your wonderful comments and suggestions, I have enjoyed hearing them all.
Hi Stephanie,
If you're interested in pursuing a potential increase in volcanism coincident with ice sheet retreat, you might start your search in the Aleutians. There were at least four, and likely six, caldera-forming eruptions (CFE) from about 12,000 - 8,000 years ago in the central arc (Okmok, Makusin?, Fisher, Shishaldin?, Roundtop, Dutton), a span of about 500 km. Check the AVO reference library for articles. Also, there was another pulse of CFEs around 3,000 years ago (Aniakchak, Veniaminov, another Okmok?), around the time Black et al., (1975) suggest a smaller glacial advance and retreat in the area.
I would be very interested in the results of your investigation for another project I am working on. Feel free to contact me about this. Cheers
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