Composition of high frequency ambient noise from cross-correlation: A case study using a small aperture array
Weitao Wang1, Sidao Ni2, Baoshan Wang1
1 Institute of Geophysics, China Earthquake Administration, Beijing 100081, China 2 Mengcheng National Geophysical Observatory, School of Earth and Space Science, University of Science and Technology of China, Hefei 230026, China
Composition of high frequency ambient noise from cross-correlation: A case study using a small aperture array
Weitao Wang1, Sidao Ni2, Baoshan Wang1
1 Institute of Geophysics, China Earthquake Administration, Beijing 100081, China 2 Mengcheng National Geophysical Observatory, School of Earth and Space Science, University of Science and Technology of China, Hefei 230026, China
摘要Long-time cross correlation of ambient noise has been proved as a powerful tool to extract Green’s function between two receivers. The study of composition of ambient noise is important for a better understanding of this method. Previous studies confirm that ambient noise in the long period (3 s and longer) mostly consists of surface wave, and 0.25-2.5 s noise consists more of body waves. In this paper, we perform cross correlation processing at much higher frequency (30-70 Hz) using ambient noise recorded by a small aperture array. No surface waves emerge from noise correlation function (NCF), but weak P waves emerge. The absence of surface wave in NCF is not due to high attenuation since surface waves are strong from active source, therefore probably the high ambient noise mostly consists of body wave and lacks surface wave. Origin of such high frequency body waves in ambient noise remains to be studied.
Abstract：Long-time cross correlation of ambient noise has been proved as a powerful tool to extract Green’s function between two receivers. The study of composition of ambient noise is important for a better understanding of this method. Previous studies confirm that ambient noise in the long period (3 s and longer) mostly consists of surface wave, and 0.25-2.5 s noise consists more of body waves. In this paper, we perform cross correlation processing at much higher frequency (30-70 Hz) using ambient noise recorded by a small aperture array. No surface waves emerge from noise correlation function (NCF), but weak P waves emerge. The absence of surface wave in NCF is not due to high attenuation since surface waves are strong from active source, therefore probably the high ambient noise mostly consists of body wave and lacks surface wave. Origin of such high frequency body waves in ambient noise remains to be studied.
基金资助:National Natural Science Foundation of China (Nos. 40874095, 40730318 and 41004019) and China Earthquake Administration Special Program Fund (Nos. 200808078 and 200808002)
通讯作者:
Weitao Wang
E-mail: wangwt@cea-igp.ac.cn
引用本文:
Weitao Wang, Sidao Ni, Baoshan Wang. Composition of high frequency ambient noise from cross-correlation: A case study using a small aperture array[J]. 《地震学报》英文版, 2010, 23(5): 433-438.
Weitao Wang, Sidao Ni, Baoshan Wang. Composition of high frequency ambient noise from cross-correlation: A case study using a small aperture array. Earthquake Science, 2010, 23(5): 433-438.
