The document discusses rapid and gradual changes to the Earth's surface caused by volcanoes and earthquakes. Volcanoes form when magma is forced to the surface, erupting either explosively by ejecting hot debris and gases or nonexplosively through lava flows. Earthquakes are caused by elastic deformation of rocks under stress that results in seismic waves, including fast P waves and slower S waves, traveling through the Earth and causing the ground to shake.

1. Rapid and
Gradual
Changes of the
Earth’ s Surface
 Standard Three – Objective Four

2. Rapid and Gradual Changes
 Volcano-a mountain that forms when molten
rock, called magma, is forced to the Earth’s
surface.

3. Nonexplosive Eruptions
 Lava-is
magma that flows onto the Earth’s
surface.

5. Explosive Eruptions
 Cloudsof hot debris and gases shoot out
from the volcano often at supersonic speeds.

8. Don’t Try This at HOME!!

9. Earthquakes
 It is self defined!!!! Shaking of the EARTH!!!
 Seismology-the study of earthquakes.
 Deformation-the change in the shape of rock in
response to stress.

10.  Plastic deformation-rocks bend like clay, they do
not cause earthquakes.
 Elastic deformation-rocks will break, they will
cause earthquakes.

11. How do Earthquakes Travel?
 Seismic waves-waves of energy that travel through
the Earth.
 P waves-(Primary) travel through solids, liquids,
and gases, are the fastest seismic waves.

12. S waves-(Secondary) shear waves are the second-
fastest waves. They cannot travel through parts of
the Earth that are completely liquid.

13.  Surface Waves-move the ground up and down in
circles as the waves travel along the surface.