The amount of silicon, which is the main element in magma, other than oxygen, influences the type of eruption. There must be high gas pressure, for an explosive volcano to erupt. Low silica magma is known as basaltic. A lot of basaltic lava cause broad and gently slopped volcanoes which resemble shields. An eruption is the explosion of volcanic materials onto the surface, either from a central vent, a fissure, or a group of fissures.
Volcanoes can erupt in any type of season.
A volcano can even erupt in winter, but it usually is a dry eruption. Eruptions can come from the side or top of the volcano. An eruption is caused when pressure builds in a magma chamber, and magma gets forced through the conduit and out of the vents. The pressure of magma inside builds up so much that the volcano splits and the magma is forced out. The destructiveness of a volcano's eruption depends on what is in it.