15 years ago....

it kinda looked like Godzilla taking it down

Watch the IGN video. Confirms that it was some kind of seismic activity that caused the power plant to malfunction. 

***SPOILERS*****minor spoilers, but still *****SPOILERS*****read further at your own risk******

Empire Magazine, as well as the journalists (such as IGN) who viewed the 20 minutes of footage that was screened earlier today have confirmed that the '15 years ago' event is in 1999. Furthermore, they confirm it was a nuclear power plant accident that happens in Japan. At the time, Cranston's character is working at the plant, and the accident has a very personal cost for him, which causes him to investigate what happened there. 

If you read the IGN/Empire articles yourself, or read any equivalent sources who also saw the 20 minutes of footage, they go into some additional detail, but that's all I feel comfortable sharing myself. 

I'm pretty sure that whatever happened 15 years ago is what we see in the trailer with Cranston running down the hallway and I'm guessing the scene where the door closes between him and his wife. My guess is she dies because of it.  In Cranston's dialogue he says, "I deserve answers!!"  because he knows that whatever they are keeping a secret was te cause of his wife's death and he wants it stopped so that no one else has to suffer.

ya,know madison, it was just a question, i herd an interview long before the trailers realese. bryon said the same thing you said... Now i thought, the incedent took place just a little bit before this movie...like 3yrs...so it just a question

dont try to attack me like im unedjucated, because the less i know about this movies primess, the more i will love it.

I don't see how anything I said was an attack. 

You asked a question, I answered it. 

I mentioned the sources just so you knew where to look in case you wanted to know more. 

I understand not everyone has read every source, and many DO NOT WANT to read every source. They enjoy speculating more than actually knowing prior to the film's release. Which is fine.

I honestly wasn't sure whether you were more interested in knowing vs speculating, which is why I put SPOILER ALERT and gave a vague answer. 

I was trying to balance being informative and considerate. I wasn't trying to be aggressive in any way. I'm not really sure where you got that from.