Occur or happen

I am still confused by the use of 'happen" and 'occur'. Are the following sentences acceptable?

(1) A funny thing happened.

(2) A funny thing occured.

(3) Last night, a fire happened in my neighborhood.

(4) Last night, a fire occured in my neighborhood.

(5) Last night, there was a fire in my neighborhood.

(6) This morning, an earthquake happened in the island.

(7) This morning, an earthquake occured in the island.

(8) Eathquakes occur frequently in this area.