There was a great earthquake.”
καὶ ἰδοὺ σεισμὸς ἐγένετο μέγας·
Matthew is the only one who has any activity at the tomb. In the 3 other gospel stories, the woman or women found that the tomb was empty. Thus, Matthew uniquely said that suddenly there was a great seismic earthquake (καὶ ἰδοὺ σεισμὸς ἐγένετο μέγας). Matthew also uniquely had an earthquake at the death of Jesus, chapter 27:54. Now he had another earthquake at the resurrection of Jesus. These earthquakes symbolized that something important was happening.