The equipment in dashed frame is existing , the equipment in dash - dotted frame is new added 虚线内的设备是原有的,点划线内的是新加的
According to their space position , the seismic features of shallow gas in this region can be divided into three groups : ( 1 ) features in the stratum : acoustic blanket , acoustic curtains , acoustic turbidity , irregular strong top reflection boundary , and phase pull - down in both flanks ; ( 2 ) features of the seabed : seabed pockmark and giant sunken pit ; ( 3 ) features in the seawater column : acoustic plumes , cloudy turbidity and point - line - type reflection 该区的浅层气地震特征按空间位置分为3大类: ( 1 )地层中的特征:声学空白、声学幕、声学扰动、不规则强反射顶界面、两侧相位下拉; ( 2 )海底面的特征:海底麻坑、大型塌陷坑; ( 3 )海水层中的特征:声学羽流、云状扰动、点划线反射。