马尼拉海沟俯冲带前缘(21°N)海底地震仪数据处理初步成果

摘要

在马尼拉海沟俯冲带前缘开展了二维海底地震仪(OBS)探测实验,布置了一条东西走向的深地震测线——OBS2015-2.以该测线上的2个台站(OBS04和OBS08)为例,阐述了此次实验所用短周期国产OBS的数据处理流程.包括从原始数据到SAC格式、再到SEGY格式的转换;同时包括炮点位置校正和OBS位置校正.数据处理结果表明,OBS2015-2测线的数据质量良好,综合地震剖面显示来自深部的震相(如PsP、Pg、PmP等)信息十分清晰.利用Rayinvr软件正演试算,进一步确认了震相类型,特别是来自于输入板块莫霍面的反射震相非常丰富,为马尼拉俯冲带的输入板块地壳底界面的确定提供了重要的数据基础.%A two-dimensional ocean bottom seismometer (OBS) survey line (OBS2015-2) was carried out in 2015,which was an E-W trending and located in the front of the Manila Trench subduction zone.In this study,we take two OBS stations (OBS04 and OBS08) as examples to introduce the data processing flow for this short-period OBS type of data.The process includes data format transforming from original RAW data to SAC format and then to SEGY format;and it contains shot relocation and OBS position relocation.The preliminary results of data processing demonstrate that the OBS data are of high quality in this experiment.The seismic phases,such as PsP,Pg,PmP,etc.are very clear along the OBSs' seismic record sections.They are further identified by the forward modeling using the Rayinvr software.Especially,the reflective seismic phases from the Moho interface are abundant and obvious in the incoming plate along the Manila Trench subduction zone,which will provide good constraints for the crustal bottom of the incoming plate.