6.9 magnitude earthquake strikes off New Zealand coast

(CNN) -- New Zealand's capital was cleaning up Monday after a strong earthquake that shook the city and left authorities scrambling to make sure buildings were safe.

The quake struck about 35 miles (57 kilometers) south of Wellington in the channel between New Zealand's northern and southern islands. Initially reported as a magnitude-6.9 quake, the U.S. Geological Survey later reclassified its magnitude as 6.5, at a depth of 14 km (8.7 miles).

No fatalities or serious injuries were reported, but Wellington Mayor Celia Wade-Brown warned residents to be careful and "expect disruption" as the work week began. Bus service was running, but rush-hour commuter trains were idled as rail crews looked for damage.

"On the whole, most infrastructure and most buildings have been unaffected -- but we will obviously have engineers and experts double-checking the condition of infrastructure after daybreak," Wade-Brown said in a statement issued early Monday.

Perched on the edge of the southern Pacific rim, New Zealand has a long history of earthquakes. A February 2011 quake in the South Island city of Christchurch killed 185 people, most of whom died in building collapses.

Sunday's quake was the latest in a series of tremors that have jolted New Zealand's Lower North Island in the past few days.