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発表 CMP spatial autocorrelation analysis of multichannnel passive surface-wave data

作成年度 2015 年度
論文名 CMP spatial autocorrelation analysis of multichannnel passive surface-wave data
論文名(和訳)
論文副題
発表会 Society of Exploration Geophysicists International Exposition And 85th Annual Meeting
誌名 SEG Technical Program Expanded Abstracts 2015
巻・号・回 85(2015)
発表年月日 2015/10/18 ~ 2015/10/23
所属研究室/機関名 著者名(英名)
OYO Corporation USAKoichi Hayashi
California State UniversityMitchell Craig
TK Ocean-Land InvestigationsTakaho Kita
PWRITomio Inazaki
抄録
In this paper, we demonstrate that common midpoint spatial autocorrelation (CMP-SPAC) analysis of multichannel passive surface waves gives accurate phase-velocity curves, and enable us to reconstruct two-dimensional (2D) S-wave velocity (VS) structures with in laterally heterogeneous environment. Recording geometry for CMP-SPAC analysis is similar to that used for multi-channel analysis of surface waves (MASW). Ten to twenty minutes of vertical component ambient noise is recorded and divided into several blocks for spatial autocorrelation (SPAC) analysis. Processing of CMP-SPAC data consists of four steps: First, SPAC traces are calculated for every pair of receivers in each ambient noise block. Second, the SPAC traces are averaged over all blocks in the frequency domain and the SPAC traces having a common mid-point are sorted into CMP-SPAC gathers. Third, dispersion curves are calculated from each CMP-SPAC gather by comparing observed coherences with theoretical Bessel functions. Finally, a 2D VS section is reconstructed through non-linear least squares inversion. The method was applied to actual field data and compared with active surface wave data. The results from CMP-SPAC analysis using passive surface wave data are almost identical to those from common midpoint cross-correlation (CMPCC) analysis using active surface wave data. This suggests that active sources are not needed for surface wave data acquisition methods in many cases. The use of the CMP-SPAC method with passive data has the potential to greatly improve the efficiency and applicability of surface wave methods. Read More: http://library.seg.org/doi/abs/10.1190/segam2015-5913708.1
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