事件英语作文：火山喷发

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Avolcanoisanopening,orrupture,inaplanet'ssurfaceorcrust,whichallowshot,moltenrock,ash,andgasestoescapefrombelowthesurface.Volcanicactivityinvolvingtheextrusionofrocktendstoformmountainsorfeatureslikemountainsoveraperiodoftime.