Wald said the chances for a stronger aftershock diminishes as time passes.
Wald said Friday's quake was considered moderate in size and below the threshold of causing much damage.
In the Imperial Valley little in the way of damage was reported, although a few nerves may have been rattled.
Imperial County Fire Capt. Rob Scott said as the quake was going he received a call from the state Office of Emergency Services asking if there was any damage.
Scott joked that he told them to call back when it was over.
He did say there were no reports of damage or injuries caused by the earthquake in the Imperial Valley.
Imperial Irrigation District officials also said there was no report of damage to IID structures and was no interruption in service.
In Calexico, there were no earthquake-related emergency calls, according to Fire Chief Carlos Escalante.
At the Calexico Wal-Mart, shoppers were shaken by the rumbling but safe, according to assistant manager, Robert Beltran.
He said the store doesn't stack heavy items on high shelves and the larger items that are stored on the top shelves, such as ice chests, are never stacked more than two items high.
Beltran said a few items fell off shelves and a few customers were scared but no one was hurt.
Next door at the Imperial Do-It Center, Assistant Manager Pedro Sarzatti said some light fixtures high above the sales floor were broken.
The fixtures hang from the ceiling by chains. During the earthquake, the fixtures swayed and the rocking motion caused the tube lights in some of the fixtures to smack together.
What's nice about fixing earthquake damage at a hardware store, though, is that all of the equipment employees need is handy.
"You betcha," Sarzatti agreed.
At Calexico's City Hall, staffer Hiliana Figueroa said she received two phone calls moments after the building stopped shaking.
One was from a woman in San Francisco who was calling to make sure her parents were OK.
Figueroa said the woman couldn't get through to her parents right after the quake hit because phone circuits were busy.
The other woman who called asked, "Did you feel the earthquake?"
Figueroa told her she had.
At the Imperial Avenue Pic 'N' Save, employees quickly cleaned up the few items that fell off shelves and thought everything would quickly return to normal.
All of a sudden, Calexico firefighters rolled up with sirens blaring.
Turns out a passerby reported a fire at the Pic 'N' Save after seeing smoke pouring from the roof.
The smoke was actually coming from lunchtime barbecuing at Bulldog's Bar & Grill next door.
Firefighters filled out their paperwork and returned to the station.
In Brawley, police and fire crews had no calls regarding any injuries as a result of the earthquake.
Businesses did not suffer any damage either.
In Westmorland, City Treasurer Sandy Pereda said she felt a strong jolt but reported no mess at City Hall.
In Calipatria, Mireya Ramirez, library clerk at Meyer Memorial Library, said the jolt and subsequent shaking at first made her think she was dizzy. But after seeing items being moved about, she realized what she felt was an earthquake.
Calipatria police and fire had no reports of damage or injuries.
In Mexicali there also was little in the way of damage reported. However, authorities there did say cellular service was disrupted for a time throughout the city.
Prior to Friday's temblor, the Valley was last rocked by notable earthquakes in June 2000 when two moderate-sized quakes struck on the Imperial Fault Line. A series of smaller temblors numbering near 100 in a matter of hours rattled the area in April 2000.
On Oct. 15, 1979, a quake measuring magnitude-6.6 struck on the Imperial Fault, causing damage throughout the Valley. In November 1987 two sizable earthquakes, each registering above magnitude-6.0 on the Richter scale, shook the Valley several hours apart.