Semi bright flashes in the sky?

Question

in the last month or so, I've seen several flashes that lit up the entire night sky on three different occasions. The last time I saw a group of three randomly spaced flashes accompanied by a low pitch, brief humming sound that reached me about 5 seconds later. About twenty minutes later there was an earthquake. I looked up earthquake flashes and they are said to look like auroras, but the flashes i saw were completely even in brightness over the whole sky, unlike auroras. Anyone have any ideas what they might be?

Answer 1

There may have been a few auroras  that may have happened at once.  You saw one of them and it seemed like that was what caused all the light.  Was it a clear night or was it cloudy.  Clouds can disperse the light that may make it seem like it was the whole sky that lit up.