Here's why seismologists warned of an earthquake in California this week

California saw an elevated risk off its coast over the last several days from the big San Andreas fault line due to a swarm of small earthquakes.

Some reports on social media paint a grim image of possible destruction for Southern California this week, but as there was an increased concern for a magnitude 7 earthquake, the possibility of it hitting was only 1 percent or less.

Here's why it prompted an advisory from the state emergency services:

Concern came from a reported swarm of earthquakes in the Salton Sea, which is near 150 miles southeast of Los Angeles and south of the end of California’s mighty San Andreas fault.

The earthquakes in the swarm were between magnitudes 2 and 4.5.

Seismologists have been closely tracking the swarm of earthquakes near the fault, which experts consider overdue for a major earthquake, with a magnitude of 7 or greater.

The San Andreas fault’s southernmost stretch has not ruptured since about 1680, more than 330 years ago.

According to Pacific Northwest Seismic Network, seismologists can’t predict exactly when and where earthquakes will strike, but swarms near a major fault are a cause for concern, as they temporarily raise the odds.

The elevated risk has diminished, experts told the Los Angeles Times.

After working with seismologists and experts on the California Earthquake Prediction Evaluation Council, the California Office of Emergency Services released an advisory about the possibility of a stronger quake after the swarms under the sea.

If a large earthquake did in fact start at the end of the fault line, where the concern arose this week, it could create serious destruction in Los Angeles, as it could break several hundred miles of the fault, which extends past Los Angeles.

In 2008, USGS researchers simulated what would happen if a magnitude 7.8 earthquake started at the Salton Sea and then barreled up the San Andreas fault, sending shaking waves out in all directions. Shaking waves could hit from Los Angeles to Santa Barbara. The death toll could climb as high as 1,800 people, according to The Los Angeles Times.

Cal OES says the elevated risk was another way to remind Californians to be prepared for earthquakes.

Click here to learn more about the Cascadia Subduction Zone and the northwest. (Via KIRO-TV)