BANGKOK, Thailand — Residents in the northern Thai city of Chiang Mai felt a long period of shaking but saw no major damage. High-rise buildings swayed slowly for at least half a minute in the capital Bangkok, startling residents.    

The U.S. Geological Survey said the 6.1 magnitude quake Thursday morning was about 10 kilometers (6 miles) below the surface. Moderate quakes of 4.6 and 5.7 magnitude shook the same area overnight.    

It was centered about 31 kilometers (19 miles) from Chaloem Phra Kiat, which is about 280 kilometers (174 miles) northeast of Bangkok.