And behold, the curtain of the temple was torn in two, from top to bottom. And the earth shook, and the rocks were split. (Matthew 27:51 ESV)
Jesus died and a small yet strong earthquake took place. Why? What about the death of Jesus was so powerful that it caused creation to tremble? I don't know.
Was it a physical manifestation of a spiritual shift that took place? As the work of Christ on the cross was finished, did the the Earth itself react? Or was it something else?
Personally, it is enough for me to read the account and realize that there were physical geological manifestations of Christ's spiritual work. Jesus is the Rock. Upon him lay the hopes, prayers, and foundation for our eternal well-being.