Population growth and the built environment are the primary root causes of morbidity and mortality associated with earthquakes. Earthquakes generally do not cause death and injury, but rather it is the buildings in which people are located and the contents therein that are directly responsible for human mortality and morbidity. Protective action messaging is intended to provide members of the public with information that can be recalled and acted on during earthquake shaking to reduce the chance of death and injury. In order to design appropriate guidance for developing protective action messages for earthquakes, it is important to understand their human impact—that is, how people are injured and killed during earthquake shaking. The purpose of this background paper is to describe the epidemiology of deaths and injuries during earthquakes. The paper will address the major causes of death and injury from earthquakes, including what the research indicates about injuries to building occupants who walk or run, the likelihood of death or injury from earthquakes, the likelihood of death or injury from earthquake-related building collapse, the likelihood of death or injury from substandard building evacuation routes during earthquakes, and other sudden onset threats, such as tsunami or fire. The health effects of earthquakes can be categorized in a variety of ways. Combs, Quenemoen, Parrish, and Davis (1999) developed a typology, which has been adopted by the U.S. Centers for Disease Control and Prevention (CDC), for categorizing the health effects attributable to earthquakes and other disasters based on two parameters: (1) the time the death or injury occurs relative to the event, and (2) whether the event is directly or indirectly related to the disaster. Deaths and injuries that are directly related are those that are caused by the physical forces of the event, whereas indirectly related deaths and injuries are, “those caused by unsafe or unhealthy conditions that occur because of the anticipation, or actual occurrence, of the disaster” (Combs et al., 1999, p. 1125). This paper will focus primarily on human deaths and injuries occurring during earthquakes that are directly related to the event.