holy city and appeared to many people. In the Mark and Matthew accounts, the centurion in charge comments on the events: "Truly this man was the Son of God!" or "Truly this was the Son of God!". The Gospel of Luke quotes him as saying, "Certainly this man was innocent!" The historian Sextus Julius Africanus in the early third century wrote, describing the day of the crucifixion, "A most terrible darkness fell over all the world, the rocks were torn apart by an earthquake, and many places both in Judaea and the rest of the world were thrown down. In the third book of his Histories, Thallos dismisses this darkness as a solar eclipse. ..." A widespread 6.3 magnitude earthquake has been confirmed to have taken place between 26 and 36 AD. This earthquake was dated by counting varves (annual layers of sediment) between the disruptions in a core of sediment from En Gedi caused by it and by an earlier known quake in 31 BC. The authors concluded that either this was the earthquake in Matthew and it occurred more or less as reported, or else Matthew "borrowed" this earthquake which actually occurred at another time or simply inserted an "allegorical fiction". Medical aspects A number of theories to explain the circumstances of the death of Jesus on the cross have been proposed by physicians and Biblical scholars. In 2006, Matthew W. Maslen and Piers D. Mitchell reviewed over 40 publications on the subject with theories ranging from cardiac rupture to pulmonary embolism. In 1847, based on the reference in the Gospel of John () to blood and water coming out when Jesus' side was pierced with a spear, physician William Stroud proposed the ruptured heart theory of the cause of Christ's death which influenced a number of other people. The cardiovascular collapse theory is a prevalent modern explanation and suggests that Jesus died of profound shock. According to this theory, the scourging, the beatings, and the fixing to the cross left Jesus dehydrated, weak, and critically ill and that this led to cardiovascular collapse. Writing in the Journal of the American Medical Association, physician William Edwards and his colleagues supported the combined cardiovascular collapse (via hypovolemic shock) and exhaustion asphyxia theories, assuming that the flow of water from the side of Jesus described in the Gospel of John was pericardial fluid. In his book The Crucifixion of Jesus,