Lava Domes, Fracturing and Earthquakes (by )

Last Tuesday I went to the Meet the Post Doc's semaniar at UCL there were two speakers the first one was Rosie Smith with Evidence for Seismogenic fracture of Erupting Silicic magma. This was interesting becuase it was looking at the fractures that occure like in the mouth of volcanos where the magma (hot rock) is pushing upwards. This means that the rocks are hotter than normal rocks that are being deformed by say mountian building events and so the fualts break and fracture and then some of them basically anneal shut again - the fracture heals its self or the rock sort of glues itself back together again.

Again these faults and their behaviours will affect the volcano-tectic earthquakes. It is also interesting to me from a structures point of view and the effects all this fracture and annealing will have on say the minerallogy and the structural integrity of the resulting rock.

However the bit that really intrested me was her talking about the apparatus she uses to simulate what is going on - they put the rocks in machines that squash them and heat them and there are obviously alot of constraints and alot of issues as to weather the sample has been treated to get rid of water and all the rest of it.

I like these types of machines and would love to use them - they can also test the aucostics of the sample so I assume they can basically hear the fractures occuring and then propergating through their samples. However you do not seem to be able to control all three axis of stress even though it is called a Tri-axial deformation apparatus - there is also an issue with thermal gradants through the samples if you are say heating it from just the bottom etc.... they are designing new equipement which sound fun too 🙂

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