Volcanic Eruptions and their Accompanying Manifestations

Abstract

There are a large number of varieties of phenomena manifested in volcanic eruptions. They are mostly related with the characters of magmas by which respective volcanic activities are caused. In the cases where the magma comes in coetact with the underground water or some other abnormal conditions on its way ascending to the earth surface, however, volcanic eruptions may be manifested differently from those expected from the original character of the magma. Volcanic eruptions and their accompanying manifestations are listed as follows; Lava flow, lava lake formation, lava dome building, extrusion of volcanic spine, volcanic explosion, phreatic explosion, projection of fragmental ejecta, cinder cone building, projection of volcanic smoke, nuee ardente in the strict sense, pyroclastic flow of the intermediate type, pumice flow, directed volcanic blast, agglomerate flow, mud flow, formation of crater, explosion crater and fissure, fumarol formation, volcanic earthquake, explosion earthquake, volcanic rumbling, explosion sound, explosion blast wind, collapse of the volcanic edifice, melted sulphur flow, hot water flow, ground uplift, ground crack, upheaval and subsidence of the terrain, increase of the land, tilting, expansion and contraction of the ground, change of crater depth, depression and sinking around the crater (including caldera), formation of dammed lake, change in ground temperature, fumarole, hot spring, water spring and lake water, water column rising, warming and staining of sea water, tsunami, change in volcanic magnetism, lightning and thunder. The present paper deals only with principal phenomena of volcanic eruption, though there are not few accompanying manifestations inmportant for prediction of eruption.