(CNN) -- A tsunami advisory announced shortly after a 7.0-magnitude earthquake struck Japan's Ryukyu Islands early Saturday has been canceled, Japan's Meteorological Agency reported.
There was no tsunami damage "though there may be slight sea level changes from now on," it said, referring to the areas affected by the advisory -- the Okinawa Islands, the Amami Islands and the Tokara Islands.
The quake was centered 10 kilometers (6.2 miles) deep and struck at 5:31 a.m. (3:31 p.m. ET Friday) about 85 kilometers (53 miles) from Okinawa.
The quake was felt on Okinawa, with shaking that lasted about 15 seconds, said Lt. Col. Daniel King of the U.S. Pacific Command. He told CNN that commanders in Japan and Hawaii were trying to get damage and casualty reports from U.S. military stations on Okinawa, but had heard nothing in the immediate aftermath.
About 20,000 U.S. troops -- mostly Marines, along with Navy and Air Force personnel -- are stationed on eight bases on Okinawa, he said.
iReporter Kristina Donaldson, who lives in central Okinawa, said the quake "seemed to last longer than other ones we have experienced here."
"We felt the quake pretty good this morning," she said, but life there was largely unaffected.
"I just walked down to the coastline and the kids are walking to school as they always do. No sirens, or any destruction from where we are."
Okinawa resident Eric Shepherd said his grandmother-in-law described it as the strongest quake she had felt in her 90 years on the island.
"It felt like some really bad airplane turbulence," Shepherd said, adding that one of his two children slept through what seemed like a minute-long "rumble."
"I had no problem walking to the kids' room to check on them" during the quake, he said