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| | Abstract | | Our laboratory recently introduced a handheld electromagnetic induction instrument named GEM-2 (Geophex Ltd.) for near surface exploration. GEM-2 has a fixed coil separation of 1.67m and operates with several frequencies simultaneously. The exploration depth depends on the individual operational frequency and the target depth of GEM-2 is up to around 10 m. We applied the induction method with GEM-2 at several sites. We operates 5 frequency of 425 Hz, 1525 Hz, 5525 Hz, 20025 Hz and 72225 Hz, but sometimes the acquired data are highly scattered and we cannot recognized the trend of anomalies having the look at the contour of raw data. Especially the data on the low frequency side are subject to be contaminated by unstable outlier noises. The cause of the noise is probably due to electronics circuit but unknown. We tried to reduce the data so that we are easy to see the trend of anomalies. By try an error, the taking median of a range more than the survey-line width is the best reduction of the GEM-2 data so far. Here we show the data at the site of beach as examples. |
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