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09-01-2015, 10:08 AM
Hi Brian,
actually, I found the article interesting: I should read the published paper. You could be correct and I could be wrong, but I had not heard that mantle convection was linked to intraplate (within plate) quakes. This could be a big deal to earthquake hazard mapping (except, as the author stated, it is not the last word). New Madrid is not accumulating strain, yet it is a huge bulls-eye on the USA hazard maps. There is a debate on whether the seismicity there is just aftershocks from 1811-1812, or is it likely to have more M7+ quakes in, say, the next 500 years.
Also, they are correct about mountains spreading out and collapsing, except of course it is not that simple. Indeed, there is a lot of extension including normal fault earthquakes in Tibet. There are gravitational stresses that make mountains want to do this. But, there are tectonic forces that keep some of them tall. Oddly, erosion also can make mountains taller: you remove mass in the valleys by erosion, and isostacy makes the rocks uplift, and the ridges that eroded less become taller mountains. Not sure of the latest research, but the Rocky Mountains may have become taller and more rugged in the last 2 or 3 million years due to climate change (towards colder=ice)
Chris
Chris
actually, I found the article interesting: I should read the published paper. You could be correct and I could be wrong, but I had not heard that mantle convection was linked to intraplate (within plate) quakes. This could be a big deal to earthquake hazard mapping (except, as the author stated, it is not the last word). New Madrid is not accumulating strain, yet it is a huge bulls-eye on the USA hazard maps. There is a debate on whether the seismicity there is just aftershocks from 1811-1812, or is it likely to have more M7+ quakes in, say, the next 500 years.
Also, they are correct about mountains spreading out and collapsing, except of course it is not that simple. Indeed, there is a lot of extension including normal fault earthquakes in Tibet. There are gravitational stresses that make mountains want to do this. But, there are tectonic forces that keep some of them tall. Oddly, erosion also can make mountains taller: you remove mass in the valleys by erosion, and isostacy makes the rocks uplift, and the ridges that eroded less become taller mountains. Not sure of the latest research, but the Rocky Mountains may have become taller and more rugged in the last 2 or 3 million years due to climate change (towards colder=ice)
Chris
Chris