Question

which statement about the mercalli scale is true? the scale has twenty ratings for an earthquakes effects. the scale rates an earthquake based on its total energy released. the scale rates an earthquake according to how much damage it causes. the scale is most useful when scientists use data from three or more seismographs.

Explanation:

The Mercalli scale rates an earthquake based on the observed effects and damage at different locations. It has 12 levels, not twenty. The energy - based rating is done by the Richter or moment - magnitude scale, not Mercalli. Using data from seismographs is more relevant for magnitude - based scales. So, it rates an earthquake according to damage.

Answer:

The scale rates an earthquake according to how much damage it causes.