土山絢子氏（MIT博士課程４年）のセミナーを下記のとおり開催いたします。
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日時：8月26日(火) 15:30 - 17:00

場所：宇治キャンパス　防災研究所　地震災害研究センター棟２階セミナー室（C200）

講演者：土山絢子（MIT博士課程４年）

タイトル：Intermediate-depth earthquakes sweep through the Bucaramanga nest in Colombia

要旨：
Earthquakes deep below Earth's crust (depths >70 km) demonstrate that rapid, seismic rupture can occur within subducting slabs that are otherwise viscously deforming within the mantle at great pressures and temperatures. Past work has suggested metamorphism and thermal shear runaway as mechanisms to build up and sustain the high stresses necessary for rapid strain rates, but there are few constraints on how these processes redistribute stress within subducting lithosphere and drive deep earthquake behavior. We explore here how deep earthquakes 150~km beneath the surface in the Bucaramanga Nest shed light on stress transfer in a viscoelastic medium. Hidden within the apparently random collective behavior of the Nest, we observe a migrating front of seismic deformation over four years that initiates at the outer edge of the subducting slab and moves 1~km towards its cold middle. Simulating simple heat diffusion, we find the observed seismic activity can produce as much heat over 1~km as the local geotherm, pushing hot isotherms down into the slab. Our results are suggestive of a self-sustaining stress transfer mechanism, where heat generated by seismic ruptures promotes temperature-sensitive viscous deformation and metamorphism, which in turn drives further seismicity.