Abstract
The global review and future prospect on the problems such as prediction, hazard and environment related to volcanic activities are made. It is difficult to draw clear borderlines among each problem such as prediction, hazard and environment, because they are so mutually connected. Researches on the prediction have been done in connetion with the subjects in the earth’s interior, Hazards take place on the earth’s surface including the hydrosphere. Environmental problems occur in the wide range from the earth’s surface to the stratosphere and global oceanic regions. Environment : Volcanic activities play an important role for the balance of the terrestrial environment. Among the volcanic products, volcanic gas and fine volcanic ash are most important as pollution substances for the environmental aspect. Problems of climate changes due to the large loading of aerosols from huge volcanic eruptions are also important items. However, for the research of pollution, data based on continuous observations for long time are essential. The tephrochronological studies are very effective to elucidate the paleo-environment, because they can identity volcanic ashes which influenced the climate in the past. Hazards : Direct hazards by volcanic eruptions mainly occur due to "flow" (pyroclastic flow, dry avalanche, base surge, debris flow, mud flow etc.). It is the most important and urgent problem to reduce and prevent these hazards. Determination of the effective magnitude scale to express the size of volcanic eruption is an important item to be worked out. Prediction : Prediction of volcanic eruption has been adopted as one of the nationally important items of research. Seismicity, crustal deformation, gravitative variation, geomagnetic variation, geothermal activity, chemical composition of volcanic gases are continuously observed to detect the behaviour of the magma. Among these methods, seismic observations around the volcanoes play the most important role, however, according to the seismic observations of the past twenty years, many felt earthquake swarms have frequently occurred near and beneath the volcanoes, but only a few of them indicated observable forerunning events for the volcanic eruptions. It is an important research program to find special symptoms to tell the volcanic eruptions among such seismic swarm activities.
