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Deep Crustal Imaging in Binchuan, China Based on a Wavefield Decomposition Analysis Using Wavelets on the Dense Array Datasets

Description: 

Ultra dense array data (spacing <100 m) has been demonstrated to be effective in imaging shallow subsurface structure. However, their rather small apertures (usually <10 km) limit the potential to image the crustal structure at greater depth, partly due to the recorded wavefields are significantly modulated by strong heterogeneities near surface. Here we develop a method to decompose the background teleseismic wavefields and local scattered wavefields using wavelets. A soft thresholding method is exploited for noise reduction and the background and local wavefields are separated out by applying a template matching analysis. We first conduct synthetic tests and find promising results, and then apply the technique on two linear dense arrays across the Chenghai fault in Binchuan, Yunnan, southwestern China. The wave partitioning result illustrates a coherent background wavefield, which is used for receiver function calculation. Through the common-conversion-points (CCP) stacking on two linear arrays, we obtain a clear Moho interface at 52 km depth and another noticeable velocity discontinuity around 30-34 km depth in Binchuan area. The latter is interpreted as the bottom layer of middle crust, in agreement with a large-scale tomographic imaging of deep crustal structures in Yunnan region. Here we demonstrate that the wavefield decomposition technique can effectively separate the local and background wavefields, enabling utilization of small-aperture temporary arrays to image crustal structure.

Session: Earth’s Structure From the Crust to the Core [Poster]

Type: Poster

Date: 4/18/2023

Presentation Time: 08:00 AM (local time)

Presenting Author: Jia Zhang

Student Presenter: No

Invited Presentation: 

Authors