Deep earthquakes (earthquakes with origins deeper than 60 km) are of scientific importance and account for approximately one-quarter of all earthquakes. They are occasionally very large and damaging yet provide much of the data that constrain our knowledge of Earth structure and dynamics. This book opens with an explanation of what deep earthquakes are, their significance to science and how they were first discovered. Later chapters provide a description of deep earthquake distribution and clustering in both time and space; a review of observations about source properties; and a discussion of theories for the origin of deep earthquakes. The book concludes with a comprehensive literature review of terrestrial and lunar deep seismicity. Deep Earthquakes presents a comprehensive, topical, historical, and geographical summary of deep earthquakes and related phenomena. It will be of considerable interest to researchers and graduate students in the fields of earthquake seismology and deep Earth structure.