Experimental determination of mantle rheology

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The most active and destructive phenomena of the Earth's surface, volcanoes and earthquakes, have their origin in dynamic processes that take place in the mantle. These phenomena are a consequence of thermal convection taking place in the mantle. Convection in the Earth's mantle takes place over a billion year time-scale but in essence is similar to the processes taking place in a simmering pan of water, where material is heated at the bottom, rises, reaches the surface and cools. This cool material then sinks and when it reaches the bottom is heated again, in a convective cycle. In order to understand the Earth's convective cycle and its destructive side effects we need to investigate how flow of the minerals present in the mantle changes as a function of temperature, pressure and other parameters. This is done by deforming samples of the minerals under the conditions present in the mantle. Until recently, it was only possible to perform the deformation experiments at pressures found in the top 400km of the mantle. However, with the development of a new piece of experimental apparatus, the Deformation-T-Cup, it is now possible to perform experiments at conditions relevant to the top 700km of the mantle. All the major minerals present in the top 2500km of the Earth are present in the top 700km; therefore this study will be able to characterise the strength and flow properties of almost the entire mantle. In this study I will use the new apparatus to perform experiments measuring the effects of pressure, temperature and other parameters on the strength of mantle minerals. This knowledge will be used to gain a more detailed understanding of the dynamics processes taking place in the Earth's mantle, which in turn will assist in greater understanding of earthquakes and volcanic eruptions.