The 2010 mw 7.0 earthquake in haiti caused an estimated 280,000 structures to collapse or sustain severe damage and resulted in the deaths of 100,000 to 160,000 people. however, a much larger mw 8.8 earthquake in chile that same year caused an estimated 550 deaths and significantly less damage to structures. much of this difference in death toll and damage was due to the fact that chile has strict building requirements, whereas no national building code exists in haiti. what else can affect the number of deaths or amount of damage caused by an earthquake?

The amount of damage an earthquake depends on multiple factors. Of course, its strength is one of the biggest factors, but very often it is not the decisive factor. If an earthquake strikes at an area where there's higher density of population, than the chances are that there will be more dead and injured people. If the earthquake strikes a place where there's little to no people doesn't matter its strength, there will be no dead or injured people, or only very few. If there's a lot of infrastructure in the area where the earthquake appeared, there will be lot of damage, but if there's very little infrastructure, than there will be very little damage done. The warning of the population on time can also be crucial for avoiding casualties, and if it is done on time and the people are evacuated, there will be very few or no victims, but if there isn't any warning, or it is too late, than there will be much more casualties. All these things were also the difference in the earthquakes in Haiti and Chile. The one in Haiti was in densely populated area, with lot of infrastructure, and there was not warning on time, while in Chile it was in an area where there's small population density, less infrastructure, and the warning was on time so the people were evacuated.

a and b because with the other three, they simplify to something else.