“Look!” The Greek word is idou (#2400 ἰδού), and it is used to get our attention. See commentary on Matthew 1:20 (“Look!).
“veil of the sanctuary.” At the time of Christ, the Temple had two veils, or curtains. The inner veil separated the Holy of Holies where the ark of the covenant was from the Holy Place, where the menorah and table of the Bread of the Presence were, and this inner veil is mentioned in Hebrews 6:19. The second veil, the outer veil, was in front of two huge doors and together the doors and veil separated the Holy Place from the court of the Priests, where the great altar was and sacrifices were made.
The second veil, the one in front of the doors of the Holy Place, was a massive curtain that Josephus describes as being 55 cubits high and 16 cubits wide, which would be over 80 feet high and 24 feet wide (Josephus, Jewish Wars, book 5, chap. 5, para. 4; 210-214). It was a most beautiful curtain that is described as being woven from blue, purple, and scarlet yarn and fine linen, all made with mystic significance and having a panorama of the heavens portrayed on it.
“the earth was shaken.” Earthquakes were viewed symbolically as denoting the presence and intervention of God (cp. Exod. 19:18; 1 Kings 19:11). The sign of an earthquake upon Jesus’ death is indicative of God’s power being displayed through the death of Jesus on the cross. Large earthquakes were known to have occurred in Judea. Josephus mentions one during the reign of Herod the Great, “such as had not happened at any other time, which was very destructive to men and cattle” (Josephus, Antiquities of the Jews; Book 15, chapter 5, section 2).
Neither the Gospel of Mark (Mark 15:38) or the Gospel of Luke (Luke 23:45) record any geological events coinciding with Jesus’ death. All three Synoptics record the tearing of the temple curtain, but only Matthew provides details surrounding the additional signs that accompanied Jesus’ death.
“the rocks were split.” This is not referring to rocks on the ground that would have simply moved around. This is referring to the huge “rocks” that were the rock faces of cliffs and slopes, or huge rocks that were partially buried in the ground and would split rather than move. Zechariah 14:4 mentions an earthquake that will occur when Christ returns to earth and fights the Battle of Armageddon that will split the Mount of Olives itself, and create a valley running from east to west where the mountain used to be. This earthquake at the time of Christ likely caused great fissures in the ground in some places and landslides in other places. It is also possible, even likely, that the huge lentil rock that supported the Temple curtain was split, and as it fell it tore the Temple curtain.