At what intensity is there considerable damage to poorly built buildings? If you are on the first floor in a building, are you likely to feel an intensity II tremor? If the pendulum of a clock in your home stops during an earthquake, at least the intensity of the earthquake in your area? During the Lisbon earthquake in 1755, a second shock wave hit. It caused The river to pull back from its banks and then the water surged forward. What intensity do you think the second shock wave was?