During the last ten years, I have continued teaching the beginning seismology class at University of California, San Diego, and have received feedback from my students, as well as other instructors who have been using the book. The second edition is my attempt to expand on some subjects, clarify parts of the book that have proven confusing, and update the discussion of current research results. The biggest changes are to the Source Theory chapter, which now provides a more complete discussion of non-double-couple sources, stress drop, earthquake scaling, radiated energy, energy partitioning, and magnitude saturation. However, I have also tried to remain concise enough that the book can still be used for a one-quarter or one-semester class, although depending upon the pace of the class it may be necessary to skip some of the material. Sections flagged with a † are suggestions for possible areas to skip without much compromise in understanding of the remaining subjects.

The computer subroutines and data for some of the exercises can now be obtained from www.cambridge.org/shearer, which also contains links to any errors found in the text and other supplemental information that I plan to add in the future.