联合海陆地震观测研究台风激发地脉动特征及应用

The interaction and coupling between the ocean waves induced by typhoons and the solid Earth generates microseisms with seismic period of ~1-30 s. These seismic waves carry important information of the source region and recently have been used by seismologists to monitor and investigate typhoons. However, because of the lacking of near field observation of the microseisms induced by typhoons, the identification of the source region and the generation mechanism are so far still under debate. In the South China Sea (SCS) and the Philippine Sea, near-field microseisms generated by several typhoons have been recorded using ocean bottom seismometers (OBSs), and in-situ hydrological and meteorological observations simultaneously with ocean buoys and mooring stations, providing a superexcellent study opportunity. This proposal will work on these valuable observations to study: (1) Characteristics, propagation and attenuation patterns of the microseisms induced by typhoon; (2) Source region distribution of the microseisms; (3) Numerical modeling of the typhoon-induced microseisms and analysis on the generation mechanism; (4) Seismic inversion method of the typhoon center location based on the seismic signals recorded offshore and onland stations. This project will be the first attempt to investigate seismic signals generated by typhoon using both OBS and onland seismic records. The results will innovatively provide an important theoretical basis for the development of new approach of seismic monitoring of typhoons, and interdisciplinary data and technical supports for traditional methods of typhoon monitoring and research.

台风引起的剧烈海浪运动同海底固体地球耦合产生周期~1-30秒的地脉动，由于该地震信号携带台风源区信息，近年来地震学家已开始尝试利用地震学方法监测和研究台风。但由于缺乏台风近场观测数据，关于台风激发地脉动的具体源区及机理至今仍存在争议，缺乏实验验证。南海、菲律宾海多次台风轨迹附近海底地震仪（OBS）清晰记录到“擦身而过”的台风所激发的地脉动，结合台风过境时海洋浮标现场水文和气象观测，为我们提供了绝佳的研究机会。本项目拟利用这些宝贵观测资料，并结合陆上地震台记录，开展如下研究：（1）台风激发地脉动特征、传播与衰减规律；（2）台风激发地脉动源区空间分布；（3）台风激发地脉动数值模拟及激发机理分析；（4）基于地震观测的台风中心定位方法。本项目是融合海陆地震观测研究台风激发地脉动的首次尝试，研究结果将为发展基于地震学的台风监测新方法奠定基础，为传统台风监测与研究提供跨学科数据印证与技术支持。

台风引起的剧烈海浪运动同海底固体地球耦合产生周期~1-30秒的地脉动，该地震信号携带台风源区信息，为发展基于地震学方法的台风监测研究带来机会。然而台风近场观测数据的匮乏，导致台风激发地脉动的具体源区及机理至今仍存在争议，缺乏实验验证。我们以台风频发的菲律宾海域及南海海域为抓手，基于陆上地震记录（周边陆上地震台站、台阵的连续地震波形记录）和海洋观测数据（台风路径附近海底地震仪（OBS） 数据、海洋浮标/潜标系统现场水文和气象观测资料）的联合分析，结合海洋模式和地脉动激发模型数值模拟，实现了基于地震台阵的高精度台风定位，并深入认识了海上台风激发地脉动源区空间分布与激发机理。重要研究成果如下：1）台风期间海底地震仪记录的地脉动信号以源自台风中心附近的短周期地脉动为主，可能由于传播损失而难以接收到沿岸地脉动源区的长周期地脉动信号；2）当地震台阵与地脉动源区距离~小于26°，通过其定位的地脉动源区会因上地幔三重震相效应而扭曲失真，可通过引入高精度三维地球介质模型来改善；3)为避免近台阵地脉动源区定位失真并提高定位精度，我们发展了一套结合反卷积技术的多台阵联合定位方法，实现了对台风的全程且高精度追踪定位；4）台风中心附近地脉动源区的形成与台风中心附近主导波浪频率和台风移速有关，其最低频率取决于台风移动速度。本项目的研究发现以及高精度定位方法将为基于地震学的台风监测研究发展提供助力。