In this chapter, we will begin a discussion on seismology, which is the branch of geology that studies earthquakes and how seismic waves move through the earth. We will study earthquakes in much greater detail in the next chapter, so for now we will focus on building a foundation to understand how waves move in the earth. Wave movement is the basis for seismic surveys, which can tell us a great deal about the earth's subsurface structures. We can learn about the large layers in the earth, such as the mantle and core, or much more locally, like the layers of rock at a building site.
In our discussion of seismology, we will cover some of the basic types of seismic surveys, like reflection and refraction for a single layer. We will also discuss how we actually get us a picture of the subsurface, and how seismic tomography helps with imaging. By the end of this chapter, you should feel comfortable with the basics of wave propagation (like reflection vs refraction and Snell's Law) single layer seismic surveys, and how we use seismic tomography.