Late night passengers trying to head home after the earthquake hit B.C. at 11:39 p.m. PT on Tuesday were slowed down for hours when SkyTrain services were temporarily suspended.

By Wednesday morning, both the Expo and Millenium lines were operating normally, but questions remained about why the light rail trains were stalled for hours.

The South Coast was hit with the most powerful earthquake the region has seen in years late Tuesday, and Translink officials admitted they had never experienced anything like this before.

"Although SkyTrain has been designed to withstand seismic events, the earthquake triggered guideway intrusion alarms along the Expo and Millennium lines,"  said a written release from Translink to CBC.

"In the interest of the public's safety, SkyTrain service was suspended and inspections of both lines were conducted, checking for possible damage to infrastructure or obstructions on the guideway."

Stations were also closed as crews inspected sections of the elevated guideway to ensure safety.

By 1 a.m. service resumed, but by then the train service was nearing the end of operational hours for the day.

An extra train was operated from King George to Waterfront to pick up any stranded passengers.

Canada Line more seismically advanced

The Canada Line — which connects Vancouver to the Vancouver International Airport (YVR) — was not affected as it is a newer system with more advanced seismic building codes.

"Canada Line continued to run unaffected.  No intrusion alarms were triggered by the earthquake, likely because 70 per cent of the track is underground – reducing the probability of debris obstructing the track," read TransLink's release.

"TransLink will continue to have customer safety as a top priority, and the events of last night are a good reminder of the importance of being prepared," the release said.

SkyTrain is the oldest and one of the longest automated driverless light rapid transit systems in the world. The Expo and Millennium SkyTrain lines connect Vancouver with Burnaby, New Westminster and Surrey B.C.