A quiet morning was abruptly shaken when the ground rumbled beneath the feet of unsuspecting residents. What began as a subtle vibration quickly turned into a jolt strong enough to make people pause and wonder—was that an earthquake?

Dozens of individuals reported feeling the tremor, describing it as a weak to light shake that briefly disrupted their routines. While such seismic activity isn’t unusual for the region, this particular event has stirred renewed concerns among experts.

That’s because it occurred along a fault line known for its volatile history. Scientists have long warned that this area, dense with geological tension, could be on the brink of something far more destructive in the coming years.

Only then did it become clear: a 3.3 magnitude earthquake had struck near Borrego Springs, in the U.S. state of California—roughly 87 miles north of San Diego. Though relatively minor, the tremor was felt widely and landed near the infamous San Jacinto Fault Zone, a sibling of the even more feared San Andreas Fault.