1) The magnitude of the quake

2) The depth of the quake

3) The nature of the surface (bed rock/loose /regolith/clay/ alluvium etc

4) Nature of the tectonic movement occurring.

As said, above, the impact on people will vary according to nature of landuse and population density.

Some countries are more densely populate than others. The more densely populate countries have more destruction. There are Mir buildings to fall down.

Some countries have vast areas of mostly unpopulated land such as jungles, desserts and water. These areas have very few casualties.

Some countries have better and more solid construction of buildings. Very often buildings are built in such a way as to minimize damage.

Some countries have better transportation and communication. Aid can be given to the people who suffer from the hurricane. Fewer die, have serious medical problems and are short of food and water.