The advisory for San Diego County was canceled on Friday night. There have been no reports of major damage in the region.

Waves emanating to the southeast from the epicenter of Thursday night's temblor -- the fifth largest in the world to be recorded since 1900 -- arrived in San Diego County about 8:30 a.m. on Friday, bringing "significant tide fluctuations" in several areas, according to the National Weather Service.

The swells caused the ocean to briefly rise 2.8 feet in La Jolla, 1.2 feet at San Diego Navy Pier and 2.6 feet in northern Imperial Beach, the NWS reported.

Meteorologists and seismologists said local quake-spawned ocean surges could continue into the nighttime hours, producing strong currents potentially dangerous for surfers, swimmers, boaters and coastal structures. Irregular stretches of shoreline could increase wave heights in some areas.

"There's no reason to be alarmed -- just be aware," said Maurice Luque, a spokesman for the San Diego Fire-Rescue Department. "We don't expect any inundation of water."

About a dozen extra SDFRD lifeguards were called in Friday morning as a precaution, and 30 police officers were sent out to patrol the San Diego coastline.

The U.S. Coast Guard prepared for any tsunami-related emergencies in the San Diego area by readying an MH-60 Jayhawk helicopter, the cutter Haddock and three response boats.

Additionally, a crew from the federal maritime agency's local Incident Management Division was on duty to respond to any pollution that could result from vessel groundings.

The Coast Guard advised boaters to keep their vessels moored pending cancellation of the tsunami advisory and asked them to monitor VHF Channel 16 for any updates or additional alerts.

At Quivira Basin in Mission Bay, the water level rapidly fell by roughly three feet about 9 a.m. Friday, according to Luque. The harbor was returning to its prior level a half-hour or so later.

Out-of-the-ordinary small waves and "unusual ripples" continued to jostle the man-made bay at midday, Luque said.

"It's not disruptive," he said. "It's a very gentle flow of water. It's not knocking boats around on the docks or anything like that."

Eventually, however, the tsunami surges in the harbor did cause some trouble. In the late afternoon on Friday, lifeguards learned that the swells had caused a 150-foot-long barge anchored in Mission Bay to buckle in the middle and break free from its tethers, Luque said.

The craft, essentially a floating platform used by a private owner to sell bait to fishing crews, sideswiped several boats while drifting through the harbor, causing minor damage, Luque said. Officials sent in tow vessels to pull the barge out of maritime lanes in the area.

In the far northern reaches of the county, the waters of Oceanside Harbor rose two or three feet at one point during the morning, but caused no reported damage, police Lt. Leonard Mata said.

Roughly 15 miles to the south, the ocean pulled back unusually far in the late morning, briefly expanding the width of the shoreline in the area, Solana Beach senior lifeguard Rob McPhee said.

"The average person probably wouldn't have noticed anything unusual, though," he said.

In other local coastal cities, including Encinitas and Del Mar, public-safety personnel noted no effects whatsoever from the tsunami activity.

A man visiting a San Diego beach prior to the arrival of the weak tsunami surges told a local TV station he was not concerned.

"Not at all -- people are out, and there's been no warnings or anything, so I think it will be pretty mild," the man, who identified himself only as Richard, told the news station. He added, however, that he would leave if hazard signs were posted.

Earlier Friday morning, the tsunami reached Hawaii, where no major problems were reported. When it hit the West Coast of the United States, however, it caused significant damage and swept five sightseers out to sea in Crescent City and southern Oregon, according to news accounts. Four of the victims were rescued, but one remained unaccounted for as of early evening.

Some property damage also was reported in Ventura Harbor and other locations, according to the Weather Service.

The quake, believed to be the largest in Japanese history, struck the northeast reaches of the East Asian island nation at 9:45 p.m. Thursday San Diego time, destroying buildings 240 miles away in Tokyo and triggering a 30-foot tsunami.