CSEDI: Collaborative Research: Thermal, Petrological, and Seismological Study of Subduction Zones

世界上大多数地震发生在俯冲带，在那里海洋岩石圈下降到地幔中。发生在40-300公里深处的中深度地震和水向地幔的输送与俯冲岩石圈中的变质反应密切相关。研究人员建议通过将地震学观测与热、岩石学模型结合起来，更好地理解俯冲带的过程。为了验证中深度地震活动性的脱水脆化假设，研究人员将建立一组俯冲带的二维运动学-动力学热模型，这些俯冲带跨越了俯冲参数的范围，包括观测到的地震活动性沿走向变化显著的区域。将系统地评估和重新定位全球和区域地震活动数据集中的事件，以验证以下假设：(a)上部地震带局限于俯冲的基性地壳，(b)下部地震带与俯冲的地幔中的脱水反应有关，以及(c)弧前地幔是地震的。将使用新的相图和岩石性质数据库创建俯冲岩石圈的岩石学模型，并根据观测到的地震体波频散对所得到的分层地震速度模型进行测试。将地震观测与矿物物理计算相结合，量化弧前地幔水化作用（蛇纹石化）的数量和分布。--

EAR-0215534van Keken Most of the world's earthquakes occur in subduction zones where oceanic lithosphere descends into the mantle. Intermediate-depth earthquakes, which occur at 40-300 km depth, and the transport of water into the mantle are intimately linked to metamorphic reactions in the subducting lithosphere. The researchers propose to better understand subduction-zone processes by integrating seismological observations with thermal and petrological models. In order to test the dehydration-embrittlement hypothesis for intermediate-depth seismicity, the investigators will construct two-dimensional kinematic-dynamical thermal models for a set of subduction zones that span a range in subduction parameters and that include regions with significant along-strike variations in observed seismicity. Events in global and regional seismicity data sets will be systematical evaluated and relocated in order to test the hypotheses that (a) upper seismic zones are confined to the subducting mafic crust, (b) lower seismic zones are related to dehydration reactions in the subducting mantle, and (c) the forearc mantle is aseismic. Petrologic models of subducting lithosphere will be created using new phase diagrams and rock property data bases and the resulting layered seismic-velocity models will be tested against observed dispersion of seismic body waves. The amount and distribution of forearc mantle hydration (serpentinization) will be quantified by integrating seismological observations with mineral physics calculations. --