There's a 5 percent chance that the 5.1 magnitude earthquake that shook Los Angeles last night was the foreshock to a larger event, seismologists say.
"[The percentage chance] is something that we've established over a decade of research," said Justin Pressfield, a spokesman for the U.S. Geological Survey, echoing earlier statements by well-regarded seismologist Lucy Jones.
"There could be even a larger earthquake in the next few hours or the next few days," Jones said during a media briefing at Caltech, according to the LA Times.
There have been more than 100 aftershocks following the late Friday temblor, including some close to magnitude 4, which can easily be felt.
But this number of aftershocks has been "well in the range of normal," Pressfield said.
Aftershocks can go on for days and sometimes weeks as the ground settles back into a stable position.
The quake Friday was not connected to the 4.4 magnitude event in the area on March 17, since they occurred on different fault systems, Pressfield said.
"But it's a nice reminder in these two relatively tame earthquakes that something bigger could happen at any moment," he added.
It's impossible to predict earthquakes with current scientific knowledge, though the U.S. Geological Survey is working on a device that will be able to alert people to an earthquake four seconds before it is felt.