1. Section 10-3 Explain the 2 factors that determine whether a volcanic eruption will be explosive or quiet. Describe the 3 basic forms that a volcano can take. Define tephra. Explain the 2 factors that determine whether a volcanic eruption will be explosive or quiet. Describe the 3 basic forms that a volcano can take. Define tephra.

2. The 2 factors that determine whether an eruption is explosive or quiet are: 1.the amount of water vapor and other gases trapped in the magma 2.whether the magma is basaltic or granitic Basaltic magma produces quiet, non-explosive eruptions and trapped gases can escape easily.quiet, non-explosive eruptions Granitic magma produces explosive, violent eruptions because the magma is thick and contains a lot of silica. Because it is thick, it gets trapped in vents causing pressure to build. It also has high water content which when trapped causes explosive eruptions.explosive, violent eruptions The 2 factors that determine whether an eruption is explosive or quiet are: 1.the amount of water vapor and other gases trapped in the magma 2.whether the magma is basaltic or granitic Basaltic magma produces quiet, non-explosive eruptions and trapped gases can escape easily.quiet, non-explosive eruptions Granitic magma produces explosive, violent eruptions because the magma is thick and contains a lot of silica. Because it is thick, it gets trapped in vents causing pressure to build. It also has high water content which when trapped causes explosive eruptions.explosive, violent eruptions

3. The form of a volcano depends on if the eruption is quiet or explosive and the type of lava. The 3 basic forms of volcanoes are shield, cinder cone, and composite. The form of a volcano depends on if the eruption is quiet or explosive and the type of lava. The 3 basic forms of volcanoes are shield, cinder cone, and composite.

4. Shield Volcano It is a broad volcano with gently sloping sides. It is built by quiet eruptions of basaltic lava which spread out in flat layers. The Hawaiian Islands are shield volcanoes. It is a broad volcano with gently sloping sides. It is built by quiet eruptions of basaltic lava which spread out in flat layers. The Hawaiian Islands are shield volcanoes.

6. Cinder Cone Volcano It is a steep-sided cone volcano with explosive eruptions that throw lava into the air where it hardens. Tephra is the lava that is blasted into the air by violent eruptions and solidifies as it falls to the ground as ash, cinders, and volcanic bombs (larger rocks). It is a steep-sided cone volcano with explosive eruptions that throw lava into the air where it hardens. Tephra is the lava that is blasted into the air by violent eruptions and solidifies as it falls to the ground as ash, cinders, and volcanic bombs (larger rocks).

8. Composite Volcano It’s eruptions vary between quiet and violent. Explosive periods release gas and ash to form a tephra layer and then a quiet period erupts lava over the tephra layer. This cycle repeats to form alternating layers. It’s eruptions vary between quiet and violent. Explosive periods release gas and ash to form a tephra layer and then a quiet period erupts lava over the tephra layer. This cycle repeats to form alternating layers.

10. Types of Volcanoes