“Two faults in the San Francisco Bay Area are ‘holding hands’ and could trigger a devastating earthquake,” reported livesience.

The newly identified fault line is capable of a powerful quake that would impact 20 million residents of Los Angeles and San Diego, according to a study published Tuesday. “The fault runs under water from San Diego Bay to Seal Beach in Orange County and on land through the Los Angeles basin,” reported usatoday.

A number of faults run along the Bay Area, creating a web of potential seismic activity. However, low-resolution mapping previously left scientists wondering where these faults might connect, and how.

Researchers have determined that the Hayward Fault and Rodgers Creek Fault connect beneath San Pablo Bay, the estuary that forms the northern part of San Francisco Bay. The newly identified fault line is capable of a powerful quake that would impact 20 million residents of Los Angeles and San Diego. “The fault runs under water from San Diego Bay to Seal Beach in Orange County and on land through the Los Angeles basin,” according to AGU.

“Given the population in the affected area, an earthquake this strong is likely to be very deadly,”  techtimes reported. More than 2.4 million people currently live right along the fault and the whole area is populated by around 7.5 million people. “Gas, water, major transportation and electrical lines also cross this fault, which means that a big earthquake would be very disastrous,” stated usatoday.