California could indeed be hit by a major earthquake and a tsunami, but not in the same magnitude as the one depicted in the new action-adventure film "San Andreas," which stars Dwayne "The Rock" Johnson, according to a new study.

Geologist Mark Legg from Legg Geophysical spoke with NBC News about this possible catastrophe, pointing out that people have not paid much attention to the hazards caused by earthquakes and tsunamis.

"That has not been looked at carefully when it comes to the potential for large earthquakes and tsunamis from offshore faults," he said.

Lucy Jones, science adviser for risk reduction in the US Geological Survey's Natural Hazards Mission Area, insisted that the matter has actually been looked into, and that experts agree that offshore faults deserve further study.

"It's a complicated picture, and this is an important piece of it," she said.

Legg's latest research paper, which will be published in the Journal of Geophysical Research: Earth Surface, reveals that the underwater seismic region known as the California Continental Borderland is currently in a "complicated logjam" of faults due to the smash-up of the Pacific tectonic plate and the North American plate.

"There's a smoking gun," Legg said of a possible tsunami, although it would not be the same as the ones experienced earlier by Cascadia or Sumatra, or even "San Andreas."

"It doesn't have to be a Sumatra-sized tsunami," he said. "It could be a 1- or 2-meter surge. That could have a huge impact on the ports."

What's important right now, Legg said, is for people to start preparing for such a huge disaster. "Worrying doesn't do anyone any good," he said. "Preparedness is the key."