資源探査と大規模データプロセッシング

[2305] Remote sensing with a new vegetation index for detecting vegetation anomaly caused by metal deposits

Hede Arie Naftali Hawu¹, 柏谷公希¹,^○小池克明¹, 櫻井繁樹², 古宇田亮一³, 山田亮一⁴ (1.京都大学大学院工学研究科, 2.京都大学大学院総合生存学館, 3.国立研究開発法人産業技術総合研究所, 4.東北大学大学院理学研究科)

司会:木崎彰久(秋田大学)

Keywords:衛星リモートセンシング, 植生指標, 金属鉱床探査, 反射スペクトル, Landsat ETM+画像

A new vegetation index (VI) using reflectances from visible green to short-wave infrared region, VIGS (Vegetation Index considering Greenness and Short-wave infrared), is proposed so that VI can accurately detect vegetation stress caused by metal deposits in areas covered by thick vegetation. A set of laboratory experiment using Japanese mustard spinach is undertaken to investigate the change in reflectance spectra depending on the concentration of selected four metals (Cu, Pb, Zn, and Cd) in soils. The results demonstrate that the VIGS values can enhance the stress difference depending on the metal contents in soils more sensitive than traditional indices. VIGS is furthermore examined for two mineralized areas containing hydrothermal copper deposits in Jambi, central Sumatra, Indonesia and kuroko deposits in the Hokuroku area, northern Japan. In the Jambi area, the Cu, Pb, and Zn contents are found to be strongly correlated with the geology and controlled by the faults through a kriging interpolation of the point content data. Using one Landsat ETM+ scene image after atmospheric and topographic corrections, the VIGS values are calculated by a combination of the reflectances of bands 2, 3, 4, 5, and 7. An ffectiveness of VIGS is proved by this case study because the VIGS anomalies are appeared on the high content zones common to the three metals. This concordance is probably originated from that the plant formations (mainly the primary forest) in the high metal zones are closely related to the geological units. VIGS anomalies are also appeared around the developed mines of kuroko deposits in the Hokuroku area. A noteworthy feature is that the anomalies become remarkable with approaching the deposits. Those results verify the applicability of VIGS to metal exploration under the vegetation.