Katsuaki Koike

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Sea eutrophication is a natural process of water enrichment caused by increased nutrient loading that severely affects coastal ecosystems by decreasing water quality. The degree of eutrophication can be assessed by chlorophyll-a concentration. This study aims to develop a remote sensing method suitable for estimating chlorophyll-a concentrations in tropical(More)
Understanding spatial distribution of rock fractures is significant to various fields in geosciences. It is, however, difficult to obtain a realistic fracture model because the amount of fracture data is small and their l ocations are strongly biased in a study area. Data are usually taken by borehole investigations and then, spatial correlation structures(More)
An understanding of the geomorphology and distribution of surface materials on an active volcano is crucial to characterize eruptions and mitigate volcanic hazards. For volcanoes, synthetic aperture radar (SAR) remote sensing is the only useful observation and monitoring technology that can be undertaken in any weather condition. This letter uses the data(More)
Field mapping activity for an active volcano mainly in the Torrid Zone is usually hampered by several problems such as steep terrain and bad atmosphere conditions. In this paper we present a simple solution for such problem by a combination Synthetic Aperture Radar (SAR) and geostatistical methods. By this combination, we could reduce the speckle effect(More)
The Wenchuan earthquake was a destructive earthquake that measured at 7.9 Mw occurred at 14:28:01.42 CST on May 12, 2008 in Sichuan province of China, which induced large quantities of secondary mountain disasters such as collapse, landslides, debris flows and barrier lakes. These disasters occurred and more seriously formed disaster chains causing great(More)
Spatial variations in tritium concentrations in groundwater were identified in the southern part of the coastal region in Fukushima Prefecture, Japan. Higher tritium concentrations were measured at wells near the Fukushima Daiichi Nuclear Power Station (F1NPS). Mean tritium concentrations in precipitation in the 5 weeks after the F1NPS accident were(More)