JpGU-AGU Joint Meeting 2017

Presentation information

[JJ] Poster

H (Human Geosciences) » H-TT Technology & Techniques

[H-TT26] [JJ] Near Surface Geophysics

Wed. May 24, 2017 10:45 AM - 12:15 PM Poster Hall (International Exhibition Hall HALL7)

convener:Kyosuke Onishi(Public Works Research Institute), Toru Takahashi(Fukada Geological Institute), Kunio Aoike(Oyo corporation), Keisuke Inoue(国立研究開発法人 農業・食品産業技術総合研究機構)

[HTT26-P13] Multi-offset reflection records from point scatterers and velocity analysis

*Kyosuke Onishi1, Hiroshi Kisanuki1, Takanori Ogahara1, Tomio INAZAKI1 (1.Public Works Research Institute)

Keywords: GPR, velocity analysis, scatterer

Ground-penetrating radar records include a lot of reflection events from point scatterers. Soil and ground in near surface includes many stones which are smaller than a typical wave length of propagated electro-magnetic waves of ground-penetrating radar. This relationship is far difference from standard reflection seismic records which include mainly reflection events from continuous layer boundaries. Records of ground-penetrating radar show a lot of diffraction patterns from small scatterers which are frequently main survey targets of the ground-penetrating radar surveys. When applying migration processing for the ground-penetrating radar records, the events from point scatterers sometimes change difficult to be detected in background waves. Therefore, migration processing is frequently skipped in the processing of ground-penetrating radar. The other characteristic issue due to point scatterers in ground-penetrating radar survey is much noise in a semblance panel for velocity analysis. Point scatterers are not normally located just below the survey line. A point scatterer located with the same length of propagation path but not located just below the survey line must be located in a shallower zone from a point scatterer located just below the survey line. Different depth zones frequently have different dielectric constant and the reflection event from a point scatterer not located just below the survey line, which is frequently located in a different velocity zone, makes a strong error event in the semblance panel. We want to discuss this issue and try to avoid it using 3D multi-offset records.