Pick the correct value from the following options.

The destructive earthquakes have magnitudes higher than ______ on the Richter scale.

Earthquakes having magnitude 6-7 on the Richter scale are said to be strong with an effect of moderate damage in populated areas. 

And earthquakes with a Richter scale reading of above 7 are of disaster level with an effect of serious damage over a large area and even loss of lives.