马里亚纳俯冲带地震活动特征及其热-岩石学机制

马里亚纳俯冲带是全球典型的缺少大逆冲地震且富含水的俯冲系统。俯冲带内中小地震频发，板间最大地震震级不超过7级，而板内超过7级的地震时有发生。然而，近年来地震观测显示俯冲带地震活动富有多样性，地震活动特征与热-岩石学过程之间的内在关系仍需进一步研究。本项目拟充分利用马里亚纳俯冲带地震观测数据，计算地震震级-数量-深度分布直方图和地震b值空间分布，多角度定量刻画板间/板内地震活动特征；基于已有地球物理资料构建热结构有限元模型，以“科学”号新采集的关键区域地表热流数据为约束，探明俯冲带板间实际摩擦和剪切生热量，获得精确的俯冲带板间/板内温度结构，并结合岩石水化/脱水实验结果，刻画俯冲带板间/板内岩石水化/脱水等热-岩石学过程；综合地震活动特征与热-岩石学过程的研究结果，建立二者之间的内在联系，进而揭示岩石水化/脱水过程对地震成因机制的重要作用，为研究俯冲带地震活动提供新的热-岩石学依据。

The Mariana subduction zone is a typical subduction system in the world with abundant water and lack of megathrust earthquakes. Moderate and small earthquakes occur frequently, and the largest magnitude of interplate events is no more than 7, while intraplate events with a magnitude greater than 7 occur occasionally. However, recent seismic observations show rich complexity, so the relationships between characteristics of seismicity and thermo-petrological processes still need further study. This project intends to compute magnitude-quantity-depth histogram of seismicity and the spatial distribution of seismic b-values, to quantify the characteristics of interplate/intraplate seismicity. The thermal structure will be constrained by the newly collected heat flow data via “Science”, to investigate the real friction and shear heat and the accurate thermal structure. Combined with rock hydration/dehydration experiments, the thermo-petrological processes such as rock hydration/dehydration are characterized. And the relationships between the characteristics of seismicity and thermo-petrological processes are built to reveal the effects of hydration/dehydration reactions on the seismogenic mechanism. The project will provide new thermo-petrological evidence for the study of subduction seismicity.