利用HVSR法探测渭河盆地浅部构造

Near-Surface Structure of Weihe Basin Detected by HVSR Method

利用渭河盆地眉县至扶风段地震测线的连续地震背景噪声数据,基于噪声水平和垂直向谱比(HVSR)法,得到各台站HVSR曲线;再通过频率与深度的转换关系,获得测线下方近地表第四系沉积层结构埋深。结果显示,盆地第四系沉积层厚度呈U型分布,由盆地两侧向中间腹部逐渐变厚,两侧厚度为100~400 m,中部厚度为400~600 m;沉积层深度剖面在距测线起点25 km和33 km处明显表现出沉积界面间断跳跃特征,该变化与岐山-马召断裂和扶风-乾县断裂在空间位置上有较好的一致性。

This paper selects the continuous seismic background noise of seismic survey line from Meixian to Fufeng in the Weihe basin.Based on the HVSR method,the HVSR curves of each station are obtained.The structural characteristics of the Quaternary sedimentary layer near the surface below the survey profile are obtained through the conversion between frequency and depth.The results show that the thickness of the Quaternary sedimentary layer in the basin is in a U-shaped distribution,gradually becoming thicker from both sides of the basin to the middle of the basin.The depth on both sides is 100 to 400 meters,and middle of the basin is about 400-600 meters.The depth profile of the sedimentary layer shows intermittent and jumping characteristics at 25 km and 33 km from the starting point of the survey line,which is in good agreement with the Qishan-Mazhao fault and Fufeng-Qianxian fault in spatial location.