Pollution in the sea is nothing new, but scientists have yet to realize the extent of the damage man's activities on land has done.
According to Science Alert, experts in the field were able to unearth the mystery's answer by creating a 3D model of the fault zone with the help of a machine-learning algorithm.
Based on their study, they found that some fluid might be the culprit, probably carbon dioxide in liquid form or water, which possibly breached a barrier of the underground rock and changed the balance of pressure and the friction along the fault line.
This could have led to a series of minor tremors in the area.
Unlike a significant earthquake wherein one major event is followed by minor tremors, an earthquake swarm does not have any significant event.
The Cahuilla swarm, as it is known, occurred near Mt. San Jacinto in southern California.
"We used to think of faults more in terms of two dimensions: like giant cracks extending into the earth," said Ross. "What we're learning is that you really need to understand the fault in three dimensions to get a clear picture of why earthquake swarms occur."
