| A | B |
|---|
| caldera | A large circular depression, or basin, at the top of a volcano. |
| cinder-cone volcano | A steep-sloped volcano, formed from sticky volcanic material after explosive eruptions occur. |
| composite-cone volcano | A kind of volcano formed when explosive eruptions of sticky lava alternate with quieter eruptions of volcanic rock bits. |
| hot spot | A place deep within Earth's mantle that is extremely hot and contains a chamber of magma. |
| island arc | A chain of volcanoes formed from magma that rises as a result of an oceanic plate sinking into the mantle. |
| lava | Magma that flows out onto Earth's surface from a volcano. |
| magma | The hot, molten rock deep inside the Earth. |
| rifting | The process by which magma rises to fill the gap between two plates that are moving apart. Rifting in eastern Africa may split the continent into two parts. |
| seismograph | An instrument that records the intensity, duration, and nature of earthquake waves. |
| seismometer | An instrument that detects and records Earth's movements. Data from the seismometer may predict a volcanic eruption. |
| shield volcano | A large, gently sloped volcano; formed when lava flows quiety from a crack in the Earth's crust. |
| volcano | An opening in Earth's crust through which hot gases, rock fragments, and molten rock erupt. |
| active volcano | A volcano that erupts constantly. |
| intermittent volcano | A volcano that erupts on a regular basis. |
| dormant volcano | A volcano that hasn't erupted in a while but could erupt in the near future. |
| extinct | A volcano that has not erupted in recorded history. |
