Issues for mitigating sediment related hazards around active volcanoes|personal perspectives|

Nobuo ANYOJI

The author briefly reviews the articles, reports, notes and presentation papers on debris movements or related issues around active volcanoes that have been published in the Journals and the annual workshops proceedings of JSECE. Research themes on sediment movements of two third are on debris flows and lahars that seems to appear the most frequent events in volcanic area are focused. The trend of the presentation numbers in the annual workshops seems to be followed the occurrences of volcanic eruption and related sediment hazards in these forty years. Particularly the Unzen Volcano eruption, 1990|1995, gave a lot of opportunities on researches in active volcanoes. The author classifies the agents on sediment movement initiation that are characterized in active volcanoes. Volcanic events such as pyroclastic flows and so on can be the trigger of sediment movements directly and juvenile pyroclastic deposit can be one of the mechanical factors of remobilizing sediment in the vicinity of active volcanoes. To enhance studies in volcanoes, the author makes a point the necessity of forecasting technique that will support the disaster prevention programs in active volcanoes in tomorrow. Field surveys can detect historical or geological eruptive events and sediment movements in detail. Some information about materials, processes of sediment movements and estimated volume are the sources of establishment for the sediment scenarios. To complete these matters, structural representation is helpful to understand events in active volcanoes in space and time series.