海马冷泉区微地震信号主成分及频率衰减特征分析

    Analysis of principal components and frequency attenuation characteristics of micro-seismic signals in “Haima” cold spring area

    • 摘要: 海底冷泉作为一种由流体喷溢引发的地质现象,在日趋进步的海洋勘探技术背景下,逐渐成为研究热点。在长周期监测的冷泉区微地震记录中,存在着大量不同类型、不同特征的微地震信号,为直观准确地描述每类信号的典型规律,需要从大量微地震信号中提取共同特点,因此,信号的统计归类与特征分析是研究海底冷泉活动的重要一环。本文从海马冷泉研究区识别出的微地震信号和与冷泉流体有关的短扰动信号出发,通过主成分分析法提取了两类信号在时间域和频率域的总体特征。对短扰动信号,通过Sompi谱分析法从第1主成分记录中提取了频率-衰减(f-g)特征,在此基础上对模拟的单频谐波信号与实际记录进行对比,推断此类信号是由不同频率-衰减成分的多组谐波信号构成。综合利用冷泉区微地震信号的特征分析结果,可为后续研究冷泉区微地震时空响应与产生机制提供理论指导,进而为评估冷泉系统的发育状态与水合物开发提供技术支撑。

       

      Abstract: As a marine geological phenomenon caused by fluid overflow, submarine cold seep has gradually become a research hotspot in the context of increasingly advanced marine exploration technology. In the long-term monitoring of micro-seismic records in a cold spring area, there are a large number of micro-seismic signals of different types and characteristics. To intuitively and accurately describe the typical laws of each type of signal, it is necessary to extract common characteristics from a large number of micro-seismic signals. Therefore, the statistical classification and feature analysis of signals is an important part of the study of submarine cold seep activities. Starting from the micro-seismic signals and short disturbance signals related to the cold spring fluid identified in the study area of the “Haima” cold spring, the general characteristics of the two types of signals in the time domain and frequency domain were extracted by principal component analysis. For the short disturbance signal, frequency-attenuation (f-g) features were extracted from the first principal component record by spectrum analysis, on which the simulated single-frequency harmonic signal was compared with the actual record. Results show that this type of signal is composed of multiple sets of harmonic signals with different f-g components. Comprehensive use of the characteristics of the micro-seismic signals in the cold spring area could provide theoretical guidance for the follow-up study of the spatio-temporal response and generation mechanism of micro-earthquakes in a cold spring area, and a technical support for the study and evaluation of the development state of the cold spring system and the development of hydrate.

       

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