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.
The most violent type of volcanic eruption is a Plinian eruption.  This is also one of the largest types of eruptions. This was the  type of eruption of the famed Mount Vesu â¦ vius in 79 AD.0% of the world's active volcanoes are found occur along destructive boundaries. Aci â¦ d-lava and composite volcanoes also cause the most violent eruptions as the lava is viscous and the opening of the volcano is sometimes blocked by hardened lava, causing a huge massive explosion during the eruption.