Yes, the sentences are passive constructions. You do not have to mention the "doer" or agent in a passive construction.
You could mention that the earthquake is the "doer" by using by the earthquake:
Five people were killed by the earthquake.
See this Google search for the string killed by the earthquake.
You could also use that prepositional phrase in your sentence:
Five people were killed in the earthquake by the earthquake.
This is because in the earthquake does not indicate the "doer", but rather it mentions a weather or disaster event (such as in the storm, in the hurricane, in the fire, etc.). In the earthquake is an adverbial phrase providing more information. You could consider it as saying in what circumstance the people were killed.
My sentence may sound a bit strange with two prepositional phrases using earthquake, but it's grammatical. As is
...of the people, by the people, for the people
which is a phrase from a speech by President Abraham Lincoln. It just happens that I've used the same word to describe both the circumstance and the "doer".
For the difference between the past and past perfect, see When is the past perfect exactly needed?.