复杂地质结构OBS地震剖面震相识别方法

Seismic phases identification in OBS seismic record sections across the complex geological structure

震相识别对获取深部速度结构至关重要.横穿加瓜海脊的T1测线东段,地形高差达3km,沉积厚度相差约2km,沉积基底变化复杂,对海底地震仪(OBS)地震剖面的震相识别增加了难度.本文以该测线东段OBS数据为例,采用地形校正、基底校正、多次波识别、正演模拟、走时投影等多种手段,开展了复杂构造的OBS震相识别研究,获得了测线下方深部速度结构模型.结果表明,采用的方法对复杂地质结构下OBS震相识别是行之有效的,相比传统的方法提供了更多且准确的震相走时信息,获得的速度模型更加可靠.

Phase identification plays a critical role in modeling the deep velocity structure.The geological structure is complex along the east part of Line T1 across the Gagua Ridge since its topography of sea bottom reaching 3 km in height and the sediment arriving at about 2 km in thickness.As a result,it is difficult to identify seismic phase in Ocean Bottom Seismometer(OBS)seismic record sections.In this paper,we adopt many methods including topographic correction,basement correction,multiple wave identification,forward modeling and travel time projection,and build a set of measures about phase identification for the complex geologic structure taking the OBS data along the east part of Line T1 as examples.The results show that these technical measures of phase identification are useful and effective for OBS data along the complex geological structure,which offers much more accurate travel-time information andobtains more reliable deep velocity structure.