Summary:
- Effusive eruptions are common in Hawaii, where lavas are mafic.
- Mafic magma pushes toward the surface through fissures.
- Eventually, the magma reaches the surface and erupts through a vent.
- The pressure builds but the lava flows fairly quietly.
- The lava is thin and fluid so that it flows over the ground like a river.
- It is not much anyone can do to stop a lava flow from destroying a building or road (Figure below) It is difficult to predict a volcanic eruption from a volcano like Kilauea.