Effects of Near-Surface Complexities on Differential Travel Times and Amplitude Ratios Between PP and Its Precursors

Zhou，Y.1,2,3,4,5; Chen，X.2; Yuen，D.6,7; Xu，M.1,3,4

2020-08-01

10.1029/2019JB019139

JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH   影响因子和分区

2169-9313

2169-9356

The characteristics of mantle discontinuities at depths of 410 and 660 km are important to study the mantle dynamics. With the advantage of global samplings, the differential travel times and the amplitude ratios of PP and its precursors (PP) have been extensively used to estimate the topography and the impedance contrast of mantle discontinuities. According to previous studies, effects of large-scale structures on the PP phase cannot be neglected. Theoretically, the complex near-surface structure, including ocean layer and crustal heterogeneity, may complicate the PP phase. It is necessary to assess the uncertainties of waveform by taking into account the near-surface complexities. Through the usage of an efficient algorithm for constructing synthetic seismograms, the effects of near-surface structure on the differential travel times and the amplitude ratios between the PP and PP are explored. We demonstrate that the crustal structure mainly affects PP-PP differential travel time with minor effects on the amplitude, while the ocean depth governs PP/PP amplitude ratio rather than the travel time. Through incorporating the crust model, the anomalies of PP-PP travel time and PP/PP amplitude ratio are globally mapped. A clear continent-ocean pattern was observed in the measurements of differential times and amplitude ratios. Moreover, time shift caused by the near-surface complexities may be wrongly attributed to the topography of mantle discontinuity and our tests show that the offset could be up to 15 km, which should be taken into account in future PP precursor studies.

SCI

英语

通讯

National Natural Science Foundation of China[41790465][41676044][91858207][41890813] ; Strategic Priority Research Program of Chinese Academy of Sciences[XDB18010304][XDA13010105] ; Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory[GML2019ZD0205] ; National Key R&D Program of China[2018FY100505] ; Guangdong NSF research team project[2017A030312002]

Geochemistry & Geophysics

Geochemistry & Geophysics

WOS:000582684200063

AMER GEOPHYSICAL UNION

GEOSCIENCES

2-s2.0-85089831143

Scopus

1.Key Laboratory of Ocean and Marginal Sea Geology,South China Sea Institute of Oceanology,Innovation Academy of South China Sea Ecology and Environmental Engineering,Chinese Academy of Sciences,Guangzhou,China
2.Department of Earth and Space Sciences,Southern University of Science and Technology,Shenzhen,China
3.China-Pakistan Joint Research Center on Earth Sciences,Islamabad,Pakistan
4.Southern Marine Science and Engineering Guangdong Laboratory,Guangzhou,China
5.School of Geodesy and Geomatics,Wuhan University,Wuhan,China
6.Department of Applied Physics and Applied Mathematics,Columbia University,New York,United States
7.College of Information Science and Engineering,Ocean University of China,Qingdao,China

Zhou，Y.,Chen，X.,Yuen，D.,et al. Effects of Near-Surface Complexities on Differential Travel Times and Amplitude Ratios Between PP and Its Precursors[J]. JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH,2020,125(8).

Zhou，Y.,Chen，X.,Yuen，D.,&Xu，M..(2020).Effects of Near-Surface Complexities on Differential Travel Times and Amplitude Ratios Between PP and Its Precursors.JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH,125(8).

Zhou，Y.,et al."Effects of Near-Surface Complexities on Differential Travel Times and Amplitude Ratios Between PP and Its Precursors".JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH 125.8(2020).