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.
Geophysical hazards: volcanic eruptions. Definition and characteristics. Volcanic eruptions happen when lava and gas are discharged from a volcanic vent. The most common consequences of this are population movements as large numbers of people are often forced to flee the moving lava flow.Volcanic eruptions often cause temporary food shortages and volcanic ash landslides called Lahar.The most dangerous type of volcanic eruption is referred to as a 'glowing avalanche'. This is when freshly erupted magma forms hot pyroclastic flow which have temperatures of up to 1,200 degrees.he most common consequences of this are population movements as large numbers of people are often forced to flee the moving lava flow. Volcanic eruptions often cause temporary food shortages and volcanic ash landslides called Lahar. The most dangerous type of volcanic eruption is referred to as a 'glowing avalanche'.