The movement attributed to the quake is less than an inch along the surface of the fault and would be virtually undetectable to an ordinary resident. But it fascinated researchers for two reasons. They are not sure what it means, and they have never seen this error move, said Zachary Ross, assistant professor of geophysics at Caltech and author of a study on the error published on Friday in the journal Science has been.
Caltech and NASA researchers acknowledge the error shift as crawling. However, according to the US Geological Survey, the phenomenon usually occurs without earthquakes.
The results come as scientists continue to warn that the "big one" ̵
1; the tremendous earthquake that could possibly plague populous Southern California – is overdue.
It began on July 4, when a magnitude 6.4 earthquake hit southern California, the study said. This led to a major shock of 7.1 magnitude 36 hours later that caused tremors as far as Arizona and Nevada. The area's low population density prevented significant damage, although nearby marine facilities require billions of dollars to repair.
The main shock broke only miles from the Garlock Fault, a major fault line that spans more than 180 miles from the San Andreas Fault to Death Valley. It has remained relatively dormant so far and has dropped 2 centimeters since the quake in July, researchers said.
The team combined advanced seismometer data with satellite imaging of fault fractures and tracked more than 110,000 aftershocks in the area over 21 days. The "domino-like sequence of fractures" heavily impacted the Garlock Fault, the researchers said.
Southern California has had some horrors, he said. The southern end of the San Andreas fault began to sneak up after the 7.2 magnitude earthquake in 2010 south of the US-Mexico border. The creep did not lead to a significant earthquake.
What does all this mean for the "big one"?
The Californians were afraid of the "big one" for a long time. However, the study proves how much is still unknown about earthquakes and how difficult they are to predict.
The USGS says that there is a 31% chance that a 7.5 magnitude earthquake will hit Los Angeles over the next 30 years. According to the census, more than 10 million people live in LA County.
The southern fault of San Andreas is usually followed by massive earthquakes every 150 years. The last one occurred there in 1857, meaning that the segment is considered a "probable location for an earthquake".
But the magnitude 7.9 quake in San Francisco in 1906 means that the likelihood of a major quake in the northern segment of the fault is slightly lower.
Seismologist Lucy Jones tweeted
that there is a 2% chance that the Big One will occur per year, and a 1: 20,000 chance per day.
The "big one" is impossible to predict. Therefore, the USGS urges California residents to stay ready, retrofit homes to make sure they do not get out of hand during a quake, and maintain a healthy supply of food, water and fuel in an emergency.
Dakin Andone of CNN contributed to this report.