Although they jangled nerves and rattled windows, probably aren't weather related or a sign of a pending Big One.
“There is nothing in this sequence, at this point, that tells us we need to be particularly worried,” said Elizabeth Cochran, a geophycist at the U.S. Geological Survey.
The two quakes belonged to a series of about 30 temblors that rattled the region in less than 24 hours.
The quakes could be a doublet, two main shocks accompanied by a series of aftershocks, she said. Or they could be part of a swarm, meaning another 4.0-ish quake could happen. But the chances of another large shaker are only about 2 percent, she added.
Nevertheless, that doesn't mean the rumbling is entirely over.
Southern California residents should brace for a series of aftershocks in the days and weeks to come, Cochran warned.
“We can definitely expect more of these small earthquakes in the magnitude range of 1 or 2," she said.
Meanwhile, scientists are working to determine which fault is responsible for the latest quakes. For now, they suspect the Whittier fault zone, a particularly active fault that was responsible for a 4.8-magnitude quake back in 2002.