Most of us here are aware of the rebound from ice masses on continents.....causes some minor quakes in certain areas.

There are several articles out recently postulating additional impact of ice loss in various scenarios.

This thread presumes there is ice loss - that's known, measured and observed - some several hundred cu meters per year over most glaciers with a few gaining some weight.....

What I'd like to explore is what could be the extent of the impact on vulcanism, earth quake on the lithosphere as the planet warms.

Big energies are involved, changes in hydrology will affect fault lines, Mt Ranier for instance is a real threat if there is an outbreak of volcanism along that Pacific chain.....

There is a link in the limited circumstance of glacial retreat and rebound pf the underlying crust, what's the furthest extent??

We know the ocean expands - what does the lithosphere do??

One article here....
http://news.nationalgeographic.com/news ... kes_2.html

More appreciated.

Like the ice extent thread I'd like this discussion limited specifically to the impact of large scale relatively fast loss of glacial mass on earthquakes and vulcanism and any other lithosphere impacts.

and from the mothership Nature...it is an emerging area of interest with too little known...

http://www.nature.com/news/2009/090917/ ... 9.926.html

Both those links are broken

I've been aware of the connection between glacial rebound and earthquakes / vulcanism for years, but my interest has been in the circa 10,000 BC area. During the end of the last glacial maximum, I'd replace the earthquake adjective minor with massive.

Funny thing about volcanoes, ash deposits on glaciers would speed the melting creating a feedback loop.

Fixed links.

Enough ash and it becomes an effective insulator but generally yes there would be a feedback loop especially local glaciers as ground warming and ash would combine to release glaciers to fall or melt or both as has happened in Iceland.

One interesting area is Western Arctic ice sheet which is vulnerable to climate change already and the glacial base is miles below sea level and already subject to volcanism.
Witches brew that as the scale is large enough if sea water gets underneath the break up would accelerate as the ice floats off - weight release might then open up more vents in the active regions.

Macdoc wrote:Most of us here are aware of the rebound from ice masses on continents.....causes some minor quakes in certain areas.

There are several articles out recently postulating additional impact of ice loss in various scenarios.

This thread presumes there is ice loss - that's known, measured and observed - some several hundred cu meters per year over most glaciers with a few gaining some weight.....

What I'd like to explore is what could be the extent of the impact on vulcanism, earth quake on the lithosphere as the planet warms.

Big energies are involved, changes in hydrology will affect fault lines, Mt Ranier for instance is a real threat if there is an outbreak of volcanism along that Pacific chain.....

There is a link in the limited circumstance of glacial retreat and rebound pf the underlying crust, what's the furthest extent??

We know the ocean expands - what does the lithosphere do??

One article here....

http://news.nationalgeographic.com/n...-quakes_2.html

More appreciated.

Like the ice extent thread I'd like this discussion limited specifically to the impact of large scale relatively fast loss of glacial mass on earthquakes and vulcanism and any other lithosphere impacts.

and from the mothership Nature...it is an emerging area of interest with too little known...

http://www.nature.com/news/2009/0909....2009.926.html

One thing it means is that we have to sink more money into researching the earth's crust and mantle. I saw an article go by just a few days ago that reported on a science project that will be drilling into the mantle sometime this summer, deeper than man has ever drilled before. They've found a spot where the crust is only five or six KM thick, and that's where they'll be drilling. The objective is to get their hands on some mantle to actually see what it's like, what it's viscosity actually is and so on. Right now it's all theory.

There is no doubt about the idea that bedrock rebounds when a great weight has been or is lifted from it. The great Canadian Shield is rebounding as we speak, and the North American ice sheet's been gone for 10,000 years, i.e., the geology of rebounding involves an exceedingly slow process, as is the case with almost all geologic processes. Yet some things can happen very quickly, like an earthquake. Volcanoes can erupt on short notice too. But plate movement is slower than mollases.

Geologist's are concerned about the Cascadia fault, which runs in a generally north-south direction off the coasts of Oregon and Washington. Big quakes have occurred along this fault in the past, the last big one was in the 1800's some time. And by "big" I mean 8.8 or bigger. A big quake today on that fault would throw up a horrendous tsunami that would wreak havoc on lower lying lands along that coast, much the way the Japanese tsunami hit the east coast of northern Honshu. A big quake on the Cascadia fault is almost inevitable. The question is of course, when? And the answer is, nobody knows, it could be tomorrow it might not be for a thousand years. But geologists think the pressue on is has built to a point where a quake is due.

As far as volcanoes go I'd not think that rebounding would induce any new action in volcano formation. The earth's mantle is already fractured into a series of some 50 plates and for the most part, volcanoes occur along their boundaries. Hawaiian volcanoes are an exception in that they sit over and slide past a hole in the mantle, which builds islands over long periods of eruption, spewing lava everywhere.

The islands do eventually slide past the hole and their volcanos go dormant, cutoff from their supply of molten rock. All but the Big Island in Hawaii have done this, and there are no active volcanoes in Hawaii except on the Big Island, Mauna Loa and Kiluea beinbg the most notable. There is a new volcano off the Southern end of the Big Island 60 or 80 miles that's a-building. It's still 6,500 feet from the surface of the ocean and geologists say it wont break the surface for five-thousand years, more or less. But it is there and it is inexorably on its way to becoming an island.

But since plate archicture is established and nobody sees the possibility of bigger plates breaking into smaller ones, the faults along which most volcanoes occur won't change. Whether rebounding will cause new volcanoes to erupt along any of those faults is the question. And right now we don't know.

The Cascades already contain active volcanoes, Mt. St, Helens in Washington State and Lassen Peak in Northern California.

Jim Hanson is pretty convinced that we have now exceeded the temperature at which what he calls "deglaciaion" will occur, by which he means that after commencing some twenty years ago, the earth's ice will melt until its gone, an irreversibe process. Won't happen overnight to be sure but it could occur within as short a time as 1000 years. He's gone back and looked at a half a dozen ice ages and plotted the earth's historical mean annual temperature with the expansion and contraction of ice sheets. He's seen that at the point ice begins to melt (instead of continuing to build), earth's temperature is at a high, which corresponds to where it stands today. The logical conclusion from this is that the cryosphere is going to melt until it's essentially gone. We have exceeded the temp at which ice can accumulate on the planet.

We're definitley in for some more rebounding. It'll be big in Greenland and perhaps Antactica.

They began in the south of what is now Sweden about 12,000 years ago, then hit south-central Sweden near modern-day Stockholm around 10,500 years ago (

Oh, and just the type of time period that interests me.

Based on the amount that the faults slipped, it seems these ancient earthquakes were massive, registering about magnitude 8—bigger than the quake that devastated Kashmir in 2005.

The models showed that thick ice could weigh down the land, preventing a fault from slipping and thereby causing it to store up that energy.The thicker the simulated ice sheets—from 325 to 6,500 feet (100 to 2,000 meters) thick—the more they suppressed earthquakes, and the bigger the earthquakes were after the ice sheets melted

I like massive too, and an 8 for that area of the world is big. I'd much rather get information on the ring of fire area along the Pacific from that time period though.

I'd just like to thank everyone for the interesting discussion! I have been reading up on seismology this week, and had only just found a couple of references to the ice related issues -- this has been really useful and informative. It's one of the things that makes reading this forum such a pleasure to find something like this crop up which is directly relevant to what you are currently looking at Cheers guys!

j x

I think the real nightmare scenario is a bad quake in Antarctica...all that ice melting and sliding off into the sea!

FACT-MAN-2 wrote:But plate movement is slower than mollases.

That's not really such a big feat.