广角地震速度结构反演中的不确定性分析

发布时间：2018-01-13 14:31

本文关键词：广角地震速度结构反演中的不确定性分析　出处：《热带海洋学报》2016年05期 　论文类型：期刊论文

【摘要】：海底地震仪(ocean bottom seismometer,OBS)广角地震探测是研究海洋深部精细壳幔结构的重要地球物理手段,其主要原理是利用广角折射/反射震相信息来反演地壳深部结构,从而为深入认识海底构造特征提供最为基础的地震学信息。文章基于地震层析成像结构反演的基本原理,针对OBS广角地震速度结构反演中可能存在的一些不确定性因素,用Tomo2D软件构建了不同的理论模型和数据体,对初始模型中沉积层的变化是如何影响整个地壳速度结构的反演结果、不同台站间距所构建的数据体对下地壳高速层分辨精度的控制影响以及不同数据体在分辨深部异常体的有效性等方面进行了分析研究,以此深入了解OBS广角地震速度结构反演中的不确定性因素。研究结果显示,地壳深部较厚(大于4km)的高速层能够被很好地反演出来,而较薄(小于2km)的高速层虽能够识别,但其形态规模恢复得较差;初始模型中沉积层速度结构的失真度影响着高速层的识别,沉积层失真度越大,对高速层的恢复越差;地壳内部存在低速层对反演高速层的规模有较为明显的影响,但低速层的厚度变化对其影响不大;对于文中10km台站间距的模型,能够识别的速度异常体规模在水平方向上最小约为5km,在纵向上最小约为3km,而20km和30km台站间距的模型最小能够识别的速度异常体规模为水平向10km、纵向3km。
[Abstract]:Ocean bottom Seismometerus (OBS) wide angle seismic detection is an important geophysical method to study the structure of deep ocean fine crust and mantle. The main principle is to use wide angle refraction / reflection phase information to retrieve deep crustal structure. Therefore, it provides the most basic seismological information for the deep understanding of submarine structural characteristics. This paper is based on the basic principle of seismic tomography structure inversion. In view of some uncertain factors that may exist in OBS wide angle seismic velocity structure inversion, different theoretical models and data volumes are constructed by using Tomo2D software. How the variation of sedimentary layer in the initial model affects the inversion results of the whole crustal velocity structure. The influence of different data bodies on the resolution accuracy of high velocity layers in the lower crust and the effectiveness of different data bodies in distinguishing deep anomalous bodies are analyzed and studied. The results show that the thicker (> 4km) high velocity layer in the deep crust can be well inversed from OBS wide angle seismic velocity structure inversion. The thin (less than 2km) high speed layer can be recognized, but its shape and scale recovery is poor. The distortion of velocity structure in the initial model affects the recognition of high speed layer. The greater the distortion of sediment layer, the worse the recovery of high speed layer. The existence of low velocity layer in the crust has obvious influence on the scale of inversion of high speed layer, but the thickness of low velocity layer has little effect on it. For the model of 10km station spacing in this paper, the minimum scale of velocity anomaly is about 5 km in horizontal direction and 3 km in longitudinal direction. However, the minimum velocity anomaly body size of 20 km and 30 km station spacing can be identified as 10 km in horizontal direction and 3 km in longitudinal direction.
【作者单位】：中国科学院边缘海地质重点实验室中国科学院南海海洋研究所;中国科学院大学;
【基金】：国家自然科学基金项目(91328206、41576041、41276049) 中国科学院卓越青年科学家项目~~
【分类号】：P714.8
【正文快照】： Foundation item:National Natural Science Foundation of China(91328206、41576041、41276049);Program for Distinguished YoungScholars of Chinese Academy of ScienceAuthor:CHEN Jinhu.E-mail:jinhuchen@scsio.ac.cn海底地震仪(ocean bottom seismometer,OBS)广角地震

【相似文献】