why did Iran experience almost 80 times more deaths in the 20th Century than California, despite having the same seismicity?

poor construction of houses

Explanation:

Majority of the people that died in Iran were as a result of poor building methods coupled with the fact that there was lack of proper regulation.

California experienced a similar earthquake but due to safer construction methods, about three people died.

Due to population boom in Iran and house shortage, this resulted in builders building cheap houses which were not strong enough.

answer: good job it's all correct !

explanation:

layers of the earth affect the waves and these effects are seen on instruiments such as seimometers