bolts? these are charleston s legendary earthquake bolts. what you see in the side of this building is not actually the earthquake bolt itself. that s the long iron rod that runs all the way through the building. reporter: what are we going to see at the fort? we re going to be seeing the effects of the earthquake. reporter: retired geology professor has spent decades researching the 1886 quake. he said the fault zone is deep and runs right through nearby historical fort dorchester. the force of the earthquake caused this to break. and moved this one towards in a left lateral sense. reporter: this comes out. and this is pushing back. it goes like this. exactly. exactly. so we have and here, the displacement is about four inches. ten centimeters. so to have the earthquake be so strong, that it breaks this, and moves it, gives you some clue what is going on. 95% of all earthquakes happen
august 31st, 1886. an estimated 7.3 magnitude quake devastated this charming southern city. two-thirds of all the brick structures in charleston were either destroyed or severely damaged. reporter: and it was felt from montreal to nebraska, cuba to bermuda. so this is the church building. and this was severely damaged in the earthquake? this was one of the most magnificent churches. the entire bell tower separated with a huge crack through the side of the building. reporter: amazingly, the building was put back together with earthquake bolts. these are charleston s legendary earthquake bolts. what you see is not actually the earthquake bolt itself. that s the long iron rod that runs all the way through the buildings. what we are going to see at the fort? we re going to be seeing the effects of the earthquake.