The political events of the 1990âs have had significant effects on the number of Member. States of the United Nations. In 1990, the entry of both Namibia and Liechtenstein made the. number of members rise to 160; however the successive union of North and South Yemen, and.
Several types of volcanic eruptions âduring which lava, tephra (ash, lapilli, volcanic bombs and blocks), and assorted gases are expelled from a volcanic vent or fissure âhave been distinguished by volcanologists. These are often named after famous volcanoes where that type of behavior has been observed.here are two types of eruptions in terms of activity, explosive eruptions and effusive eruptions. Explosive eruptions are characterized by gas-driven explosions that propels magma and tephra. Effusive eruptions, meanwhile, are characterized by the outpouring of lava without significant explosive eruption.
Volcanic Landforms Types of Volcanoes Volcanoes are classified by the types of eruption they produce. Broadly speaking, eruptions can be either effusive or explosive. Effusive eruptions are sometimes called quiet eruptions (if eruptions can be quiet!).ffusive Eruptions Effusive eruptions are those that create vast lava flows of low viscosity, fluid lava. Magma associated with effusive-type eruptions is relatively low in silica and thus easily flows up the vent and spreads across the surface. Moving across the land, these lava flows can take on two different forms.