Scientific Calendar Event

Description Earth’s asthenosphere (the 100-200 km thick shell underlying the lithosphere) plays a major role in controlling how the motions of tectonic plates evolve through time. However, uncertainties in the asthenosphere geometrical and rheological properties (i.e., its thickness and viscosity) have in the past hampered our ability to make inferences on the forces controlling plate-motion changes, and thus on the geological processes ultimately responsible for them. Recent constraints on asthenospheric properties drawn from global analyses of post-glacial rebound data alleviate this problem, but the observations on which they rely span time periods in the order of 10^3 years that are significantly shorter than the typical time-scales of plate-motion changes (10^5 to 10^6 yr). I will initially bring evidence suggesting that the properties of Earth’s asthenosphere inferred from post-glacial rebound (i.e., over 10^3 yr) remarkably apply also to the more sluggish plate dynamics (i.e., over 10^6 to 10^7 yr). I will then show how this inference offers new opportunities for the use of plates and microplates dynamics in order to assess the hazard associated with earthquake-prone crustal faults.
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