Depth variations of 410 km and 660 km discontinuities in eastern North China Craton revealed by ambient noise interferometry

Abstract

Recent studies have demonstrated that body waves between pairs of stations can be successfully retrieved from ambient noise cross correlation at both regional and global scales, although surface waves are the dominant signals. However, it is still difficult to use these retrieved body wave signals to map lateral depth variations of main structural discontinuities or velocity contrasts because of its low signal‐to‐noise ratio (SNR). In this research, based on a dense seismic array in eastern North China Craton, reflected P wave signals from 410 km and 660 km discontinuities can be successfully recovered from ambient noise cross correlation. To improve SNR, the cross correlations are stacked within each bin with the phase‐weighted stack method. The retrieved P410P and P660P phases from stacked correlations reveal lateral variations of both depths and sharpness of the 410 km and 660 km discontinuities along two profiles, which may be related with hot material upwelling and the effect of stagnant Pacific Plate in the transition zone beneath North China Craton. The imaging results are generally consistent with the results from teleseismic receiver functions, which demonstrate the possibility of mapping high‐resolution topography and sharpness of deep internal discontinuities without earthquake‐station geometric limitations.

Body Waves Retrieved From Noise Cross‐Correlation Reveal Lower Mantle Scatterers Beneath the Northwest Pacific Subduction Zone

“…Receiver function analysis shows that the deconvolved Ps converted signals vary substantially and that some show multiple phases (Tian et al, 2016). A radically changed P660P and consistent P410P waves are also observed in published results conducted for the North China Craton, ~800 km southwest to our study region (Feng et al, 2017). The amplitude ratio of the P660P may be as high as 2, even in adjacent areas with ~40% overlap.…”

“…For comparison, we chose another area (Region I in Figure 1a) at a similar latitude but far from the hinge of the slab (Li et al, 2008) to avoid the potential complicated effects, such as the significant depression of the 660 or the effects caused by the slab interface of dipping portion. The two peaks appearing at ~100 and ~150 s in the stacked waveforms (Figure 2f) correspond to the body waves reflected at the 410‐ and 660‐km discontinuities, referred to as P410P and P660P, respectively, which have been detected and explored in recent studies (Feng et al, 2017; Poli, Campillo, et al, 2012). The slowness is around zero for both phases in the vespagrams calculated by Radon transformation (Schultz & Gu, 2013) (Figures 2d, S4b, S5b, and S6b), confirming the phases are reflected at the deep mantle discontinuities.…”

“…Body‐wave extraction is a greater challenge due to its weaker energy. With the deployment of dense seismic arrays and using the stacking strategy, however, body waves reverberating in the crust and reflecting off the 410‐km and 660‐km discontinuities have recently been successfully retrieved (Feng et al, 2017; Pedersen & Colombi, 2018; Phạm et al, 2018; Poli, Campillo,et al, 2012; Poli, Pedersen, et al, 2012; Zhan et al, 2010). Even reflections from the core‐mantle boundary (CMB) and the phases through the core have been reconstructed (Poli et al, 2015; Wang et al, 2015).…”

Autocorrelation Reflectivity of Mars

“…Claerbout (1968) showed that the reflectivity series of an acoustic media can be recovered by taking the autocorrelation of the normal‐incidence transmission response, a form of seismic interferometry, that was subsequently extended to elastic media and nonnormal incidence angles by Frasier (1970). Body‐wave reflection phases have been successfully extracted by cross‐correlating (Clayton, 2020; Feng et al, 2017; Lin & Tsai, 2013; Roux et al, 2005; Tkalčić & Pham, 2018; Zhan et al, 2010) and autocorrelating (Becker & Knapmeyer‐Endrun, 2018, 2019; Phạm & Tkalčić, 2018; Romero & Schimmel, 2018) the seismic wavefield. Most recent studies have focused on the extraction of Moho‐reflected phases (e.g., PmP and SmS) to determine crustal thickness by autocorrelating and stacking the ambient noise record (Gorbatov et al, 2013; Oren & Nowack, 2017; Tibuleac & von Seggern, 2012) or teleseismic earthquake data (Delph et al, 2019; Phạm & Tkalčić, 2017).…”

Retrieval of Interstation Local Body Waves From Teleseismic Coda Correlations

“…More recently, Zhou and Paulssen () analyzed borehole seismic noise data and extracted P and S waves from noise correlations. For larger scales, many other studies have retrieved and used body waves sampling the deeper subsurface from the cross correlation of seismic noise (Boué et al, ; Feng et al, ; Lin et al, ; Nishida, ; Poli et al, ).…”