GREENVILLE, N.C. (WNCT) — The San Andreas fault line is long overdue for a major earthquake.

The North American and Pacific tectonic plates meet to make the San Andreas fault line, which stretches nearly 800 miles through cities like San Francisco and Los Angeles. A major earthquake happens along the fault every 150 years, enough time for sufficient pressure to build before the plates slip, violently shaking the earth.

The 1989 San Francisco earthquake measured a 6.9 on the Richter scale, the strongest in 83 years. Other parts of the fault haven’t slipped since 1868, and there is a 93% chance of a magnitude 7.0 quake or greater happening in the Bay area by 2045 according to the US Geological survey.