[关键词]
[摘要]
旋转地震学是研究由天然地震、爆破和周围环境振动引起的地面旋转运动的新兴学科。对于它的研究不仅有助于对质点运动(平移运动、旋转运动和形变)进行完整的描述,而且对广义地球物理学,如强地面运动地震学、地震工程学、地震物理学、地震仪器等的研究也有重要指导意义。本文系统介绍了旋转运动在地震学中4个方面的应用。首先,介绍基于平移运动和旋转运动的共同测量,得出了计算远震瑞利波和勒夫波相速度的理论公式,并以西伯利亚地震为例,得出台站附近的相速度结构;其次,利用环形激光仪仅对地震SH波敏感的特性,分离P波和S波,分辨海洋噪声和面波,确定海洋噪声的反方位角;然后,介绍利用旋转传感器对自由振荡的长周期环形模式的观测;最后,对包含旋转观测量的多参数反演问题的重要性和实用性进行了阐述,并分析了旋转地震学研究现存的问题。
[Key word]
[Abstract]
Rotational seismology is an emerging field for studying all aspects of rotational ground motions induced by earthquakes,explosions,and ambient vibrations. It is of interest to a wide range of geophysical disciplines,including strong-motion seismology,earthquake engineering,earthquake physics,seismic instrumentation,as well as to the complete description of particle motions(translational motion,rotational motion and deformation). This article mainly summarized the application of rotational motions in seismology. Based on the collocated measurements of translational motion and rotational motion,the theoretical formulas of calculating the teleseismic Rayleigh wave and the Love wave phase velocity are derived. Taking the Siberian earthquake as an example,the phase velocity structure near the station is calculated. As a ring laser is sensitive to the SH-type motion only,one of the expectations of ring laser measurements is to help seismologists separating P and S waves in the wave field. It also helps distinguish Love and Rayleigh wave energy in the ocean-generated noise field,as well as determine the back azimuth of oceanic noise sources. Then the long-period toroidal modes of free oscillatory,one of the most challenging observations in seismology,is observed with a ring laser. Finally,the importance and practicability of multi-parameter inversion including rotational observations are expounded and present the existing problems in rotational seismology research.
[中图分类号]
P315
[基金项目]
地震行业科研专项“中国综合地球物理场观测——大华北地区”(201508009)资助