The highest death tolls from earthquakes are generally due to:

There are a lot of factors that lead to high death tolls.
For example, the population density is high, this way people can't escape as quick.
Or, the technology level of the place is low, and they may not predict or announce the earthquake.
Or maybe the education level of the citizens are low, and they do not know what to do when earthquake occurs.
Even the awareness of people matters, for example earthquake does not occur frequently and they're not aware of it.

Sorry its not enough info