volcano

2. a dense, destructive mass of very hot ash, lava fragments, and gases ejected explosively from a volcano and typically flowing downslope at great speed.
4. a path along the Pacific Ocean characterized by active volcanoes and frequent earthquakes
5. The Pacific plate is an oceanic tectonic plate that lies beneath the Pacific Ocean
7. The location where two plates meet
12. a landform that forms when a volcano erupts on the ocean floor and emerges above sea level
13. a type of rock that forms when molten rock cools and solidifies
15. a sudden shaking of the ground caused by movement of tectonic plates
16. he rigid, outermost layer of Earth made of rock and minerals
18. where two tectonic plates meet and collide
19. molten rock that flows from a volcano onto the Earth's surface
20. the powdery residue left after the burning of a substance.

1. the relatively thin part of the earth's crust which underlies the ocean basins. It is geologically young compared with the continental crust and consists of basaltic rock overlain by sediments.
3. the relatively thick part of the earth's crust that forms the large landmasses. It is generally older and more complex than the oceanic crust.
6. Volcanic mountains are a special class of mountains
8. a geological process that happens when one tectonic plate slides beneath another
9. an opening in the Earth's crust that allows molten rock, ash, and gases to escape
10. he upper layer of the earth's mantle, below the lithosphere, in which there is relatively low resistance to plastic flow and convection is thought to occur.
11. a hot area in the Earth's mantle that causes volcanoes to form.
14. a mixture of molten and semi-molten rock found beneath the surface of the Earth
17. a destructive mudflow on the slopes of a volcano.