It then lows downhill from the eruption point until it cools and hardens. Main Vent ? A volcano’s main vent is the point in the Earth’s crust where hot magma has reached the surface. The familiar cone-shaped volcano builds up as ash, rock and lava ejected during eruptions fall back to Earth around the vent. Crater A volcanic crater is a circular depression in the ground caused by volcanic activity. A volcano’s vents are located at the bottom of the crater. Prophylactic
Flow – Prophylactic flows are fast moving currents Of hot gas and rock With travel down hill from a volcano, reaching speeds of 700 km/hour. The gas can reach temperatures of more than 1 ,OHO degrees C, and is one of the greatest dangers from volcanic eruptions. Ash Cloud – Volcanic ash consists of small pieces of pulverize rock and glass created during volcanic eruptions. These fragments are so small, and heated to such a temperature that they can be carried in the air for many kilometers.
Volcanic Bombs – Volcanic bombs are chunks of lava blasted into the air which solidify before they reach the ground, Some bombs can be extremely large, measuring 5-6 meters in diameter and landing more than 500 meters from the volcanic vent, Secondary Vent ? On large volcanoes, magma will reach the surface through several different vents, and not just the main vent. This can form cones, eject lava, and cause destruction. Secondary Cone – Secondary cones build up around secondary vents on larger volcanoes.