Update, 6:45 p.m.: The Nationals opened their gates at 6:40 p.m. and are planning to start tonight’s game at 7:25. The team delayed the opening of the gates “to allow D.C. inspectors and structural engineers to survey the facility,” a Nationals spokeswoman said in a statement.

Because of the delay, the Nationals will allow any unused tickets to tonight’s game to be exchanged for seats of lesser or equal to any remaining 2011 home game.

5:20 p.m.: The Nationals are delaying the opening of the center field gates at Nationals Park “until further notice” and have yet to make a definitive call on whether or not their game against the Diamondbacks will be played as scheduled following this afternoon’s earthquake. There was no apparent significant damage apparent to the stadium, but baseball operations staffers have yet to finish a complete review of Nationals Park.

Nationals officials believe the condition of the park will not prevent tonight’s game from being played. If and when team officials clear the park, one crucial obstacle for the game starting on time remains: The Diamondbacks’ team bus was stuck in traffic and arrived at the stadium around 5:15.

The Diamondbacks, in an effort to snap a six-game losing streak, planned on arriving later than usual and skip batting practice. They are staying in a hotel near the Pentagon, and their bus was stuck trying to enter the city. Nationals outfielder Jonny Gomes lives near the Diamondbacks’ hotel, and he said it took him 2 hours, 10 minutes to get to the park.

Nationals Principal Owner Mark Lerner considered arranging a police escort for the Diamondbacks, but determined that it would be impractical and ineffective.

Lerner was sitting in a conference room on the third floor of Nationals Park when the stadium began shaking. He looked out to the field and saw the enormous scoreboard in right field swaying.

“It was amazing,” Lerner said. “It was unbelievable.”

Nationals Park evacuated this afternoon, but employees and players have long since returned. A few players had already arrived at Nationals Park when the earthquake occurred.

Ryan Zimmerman and Bo Porter were in the parking lot, Manager Davey Johnson said. “They said they saw cars shaking, wobbling. It’s not something you expect.”

Said second baseman Danny Espinosa, who experienced several earthquakes growing up in Orange County, Calif.: “I just sat here. It wasn’t that big of an earthquake. Nothing fell off the walls. A good-sized earthquake would knock all this stuff out.”