马尼拉俯冲带相变与地震成因机制研究

Phase transformation and study of earthquakes formation mechanism of Manila trench

根据马尼拉俯冲带的地球物理资料,选取3条典型剖面,模拟马尼拉俯冲板块的热结构,分析俯冲板块的相变过程,探讨马尼拉俯冲带的地震成因机制。结果表明:1)B—B′剖面约在95 km深度时,洋壳开始进入榴辉岩相,C—C′剖面洋壳在160 km进人榴辉岩相;2)马尼拉俯冲带中部的地震活动倾向发生在100 km以上,南部的地震活动分布深度更深;3)马尼拉俯冲带的俯冲板块发生撕裂,使断离以下俯冲板块不容易发生地震活动,影响深源地震的发生。

According to geophysical data of Manila subduction zone, we select three typical cross- sections to simulate the thermal structure, analyze the phase transformation, and study the earthquakes formation mechanism. The results show that： 1） Oceanic crust of B--B＇ cross- section enter eclogite at about 95 km depth while C--C＇ cross-section at 160 km depth; 2） Earthquake in the middle of Manila subduction zone is tend to occur above 100 km depth, but the south is more deeper; 3）Manila subduction plate have been torn off, under where is not prone to cause seismic activity, which impact deep source earthquake.