Questions 9-10 refer to the following report.
Tower Bridge : Earthquake Damage -Preliminary Report
Risk of further quakes in the area
The area concerned is highly prone to earth tremors, and two major earthquakes (greater than 5 on the Richter scale) had been reported in the last thirty years before the most recent one. It is therefore quite likely that another major quake will affect the area in the next twenty years. It is difficult to predict the time of such a quake. However, the history of the area suggests a future earthquake of more than 7 on the Richter scale is highly improbable. Small tremors of less than 2.5, though, are considered practically certain.