Compared to most disciplines of civil engineering, geotechnical earthquake engineering is quite young. While the damaging effects of earthquakes have been known for centuries, the strong contribution of soils to the magnitude and pattern of earthquake damage was not widely appreciated until relatively recently. Fallowing damaging earthquakes in 1964 in Niigata, Japan and Alaska, and spurred by the growth of the nuclear power industry in the 1960s and 1970s, the field of geotechnical earthquake engineering has grown rapidly. Although much remains to be learned, the field has matured to the point where generally accepted theories and analytical procedures now exist for many important problems. The purpose of this book is to introduce the reader to the concepts, theories, and procedures of geotechnical earthquake engineering. It is intended for use as a text in graduate courses on geotechnical earthquake engineering and as a reference book for practicing engineers. Recognizing that geotechnical earthquake engineering is a broad, multidisciplinary field, the book draws from seismology, geology, structural engineering, risk analysis, and other technical disciplines. The book is written at a level suitable for students with knowledge equivalent to that of a senior (fourth-year) civil engineering student. The student should have had basic courses in soil mechanics, structural engineering, and hydraulics; introductory courses in geology and probability/statistics would also be helpful. Many graduate students will have had courses in structural dynamics or soil dynamics by the time they begin study of geotechnical earthquake engineering. For those readers without prior exposure, introductions to the nomenclature and mathematics of dynamic systems, structural dynamics, and probability are presented in three appendices.