A study backed by the U.S. Geological Survey reveals that California will be hit by a very strong earthquake within 30 years.

The chance that a quake with at least 6.7 magnitude will rock the state exceeds 99 percent. The odds of such a disastrous event are higher in Southern California than Northern California, 97 percent to 93 percent.

Analyzing historical records, fault line locations, tectonic movement and paleoseismological data, scientists created the first comprehensive forecast for the entire state of California.

The last time California was rocked by an earthquake as strong as the one predicted now was in 1994, when about 70 people were killed and more than 9,000 were injured, with damages of $25 billion.

“It [the study] basically guarantees it's going to happen,” said Ned Field, a geophysicist with the U.S. Geological Survey in Pasadena and lead author of the report, according to National Geographic.

The forecast predicts that Los Angeles, Orange County and San Diego have a 5 percent chance to be struck by a big quake in the following 30 years.

California is one of the most seismically active regions in the world, due to the 300 faults that traverse the state, which is situated over the meeting place of two important tectonic plates, the North American and the Pacific. Every year, Southern California is rocked by around 10,000 earthquakes, out of which most are too small to be felt.

Studies like the one created by USGS, Southern California Earthquake Center and California Geological Survey help scientists to calculate quake probabilities focused on certain regions and allow governments to take precautionary measures before the natural disasters occur.