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.
A volcanic eruption occurs when molten rock, ash and steam pour through a vent in the earth's crust. Volcanoes are described as active (in eruption), dormant (not erupting at the present time), or extinct (having ceased eruption; no longer active).Some volcanoes explode.Others are slow-flowing fountains of lava, which is hot fluid rock. The following are examples of famous volcanic eruptions.olcanoes are described as active (in eruption), dormant (not erupting at the present time), or extinct (having ceased eruption; no longer active). Some volcanoes explode. Others are slow-flowing fountains of lava, which is hot fluid rock.