Ambient noise tomography for the Ulleung basin and surrounding regions

Abstract

An ambient noise tomography is a very powerful tool to resolve shallow tectonic structure. This method can be applicable to study oceanic structures when ray paths of the station pairs cover the oceans well. The Ulleung basin is a back-arc basin which is located in the southern part of the East Sea. The study area is surrounded by various types of tectonic units including convergent zones. Several hypotheses for the origin of the study area have been proposed but it is unclear which one is more appropriate than others. Therefore, huge debates are still going on. There have been many studies on the Ulleung basin and surrounding areas using various methods. But the sparsity of the seismic network in this area makes seismic studies on the Ulleung basin and surrounding areas difficult. So, in this study, I measure Rayleigh wave group velocity by using one year long ambient noise records at the stations located in the Korean Peninsula and Japan and get group velocity maps for the Ulleung basin and surrounding regions at periods ranging between 5 and 36 s to resolve tectonic structures beneath the study area