海域天然地震资料采集方法综述

Seismological data acquisition methods in marine area

天然地震探测是提取地球深部结构信息的最有效手段之一.而海域约占地表总面积的70%,所以对海域开展地震探测十分重要.但海域有水体覆盖,海底地貌条件复杂,导致海域天然地震资料采集难度非常大,探测程度远低于陆域.针对海域地震采集环境的特殊性,人们先后发展了不同类别的海域天然地震资料采集技术.本文对埋入式、沉底式和漂浮式等传统的和新兴的非常规海域天然地震采集方法、仪器技术参数及其所采集的地震信号质量进行了介绍.然后总结了不同采集方法的优缺点.总体来看,埋入式永久海底地震台网建设成本高,不适宜大规模部署;沉底式海底地震仪(OBS)投放成本低、效率高,适合于密集台阵部署;漂浮式海域潜标地震仪(MERMAID)可以在深海区域采集强震P波信号,对全海域三维成像探测具有独特优势;新兴的海底光缆地震仪对应变敏感,适宜于海啸预警.以上信息有助于推动天然地震探测技术在海域更广泛的应用.

Seismological exploration is one of the most effective tools to extract deep earth structural information.The sea area accounts for about 70%of the total surface area of the earth,so it is very important to carry out seismic exploration in sea area.However,the coverage of sea water and the complex seafloor geomorphic conditions hinder seismic data acquisition in marine area,which leads to a much lower exploration level in marine areas than in continental areas.Several seismic data acquisition methods have been successively developed in view of the particularity of the marine environment.The present study tries to firstly introduce features,instruments and signal qualities for traditional buried-style,sinking-style and floating-style and new unconventional marine seismic data acquisition methods.Then,the advantages and disadvantages of different methods are summarized:Permanent Ocean Seismic Network composed of buried-style seismometers is expensive,inefficient and unsuitable for large-scale deployment;OBS is cheaper,more efficient,and suitable for dense array deployment;Mobile Earthquake Recording in Marine Areas by Independent Divers(MERMAID)can collect P-wave signals of strong earthquakes in deep sea areas,which makes three-dimensional imaging of the whole sea area possible;submarine cables are sensitive to strain and suitable for tsunami early warning.The summary information will help promoting the wider application of seismological explorations in marine areas.