Volcanic Eruptions

Volcanic eruptions provide routes for material deep beneath Earth's surface [blank] escape to the surface. They also allow a world to vent its heat. Active volcanoes on Earth and Venus are fed by subsurface molten rock. On Earth, the lava comes up [blank] the mantle (which is the layer under the surface). Once there's enough molten rock - called magma - and enough pressure on it, a volcanic eruption occurs. In many volcanoes, the magma rises up [blank] a central tube or "throat," and emerges out the top of the mountain. Volcanic activity can be fairly quiet, or it can be quite explosive. In a very active flow, clouds of gas may come rolling out [blank] the volcanic caldera. These are quite deadly because they're hot and moving fast, and the heat and gas and kill someone very quickly.