I believe that the San Andreas earthquake movie will be realistic. I think it will be realistic in the sense that this is what can potentially happen when the earthquake hits at its worst. This movie can possible help us prepare for the time something like that actually happens in the future.
This movie will be entertaining and most people will enjoy it. The special effects will be amazing and very captivating. However, it will just be a dramatization of people running away from the coast because the state of California is falling into the ocean. Watch this movie, it will be entertaining, but not realistic.
From the trailers for the movie "San Andreas" it appears that the focus is more on the dramatic events encountered by the actors rather than the science of tectonic plate movement. In order to achieve this end, I think its very likely that liberties will be taken with realism of a major earthquake. I really enjoy Dwayne Johnson movies but they are rarely realistic.
Upcoming disaster movie "San Andreas" seeks to build on the notion of the catastrophic earthquake that is purported to be close to happening along California's San Andreas fault. The movie will not be anywhere near realistic, but it will be an entertaining CGI filled extravaganza. Do not expect it to convey a sense of what would truly happen in such an earthquake.