A 5.1 magnitude earthquake shook the Desert Southwest Tuesday morning. It happened at 2:09 a.m. (PST)

No injuries were reported, but the temblor rattled a lot of nerves.

The mention of an earthquake in the Desert Southwest often brings back memories of the Easter Sunday 7.2 magnitude earthquake in 2010. That earthquake caused extensive damage in Calexico.

Lessons from that day helped Calexico first responders prepare for Tuesday's early morning tremor.

Chief Jim Neujahr says "Since that earthquake, it's protocal, that everytime there's an aftershock the guys go out and see if there's any obvious signs of damage."

USGS downgraded the earthquake from a magnitude 5.1 to a 4.9.

The earthquake's epicenter was just 20 miles from Guadalupe Victoria.

It was located 40 miles southwest from San Luis, Arizona.

The Easter Sunday earthquake was nearly two years ago. However scientists say after an earthquake that big, aftershocks can come years later.

Tuesday morning's earthquake could have been an aftershock -- based just a few miles away from the Easter Sunday earthquake's epicenter.

"A lot of times, from the damage that occured in the April of 2010 earthquake, a lot of times there's damage that becomes just a little worse and a little worse after every aftershock," Neujahr adds.

No damage was reported anywhere in Yuma and Imperial Counties.

However, Chief Neujahr adds during an earthquake, if you are weary about any damage, make sure to call law enforcement.