Dear native English speakers,
would both sentences sound right?
(a) The earthquake occured early in the morning when most people were asleep.
(b) The earthquake occured when most people were asleep early in the morning.
This sentence is correct, and I would use it over the first, as it provides more information. Because this is a specific event, it is better to use the phrase "in the early morning" rather than the general phrase "early in the morning".
When you use "in the early morning" it refers to the beginning part of the morning, in contrast to "early in the morning" where it sounds much more general.