As most of Hawai'i slept, a powerful, 8.3-magnitude earthquake near Japan triggered alarms thousands of miles away at the Pacific Tsunami Warning Center in 'Ewa Beach and launched a statewide network of anxious civil defense officials who feared the arrival of a killer wave.

But hours of concern ended with a whimper.

As the arc of tiny tsunamis swept into Hawai'i waters about 7:20 a.m., there was no mass devastation. They overturned a dock at Nawiliwili Small Boat Harbor on Kaua'i, tumbled a tourist off Waikiki and gave a veteran surfer the ride of his life off Turtle Bay.

"I would like to be able to say I surfed a tsunami, but I guess I didn't really," said Bobby Owens, who sat on his board as the ocean tugged him 100 yards out to sea, then brought him back.

Only the tourist, a 70-year-old visitor from San Francisco, was injured, albeit slightly. She was in the water off Kuhio Beach between 8:50 a.m. and 9:10 a.m. when the water receded about 4 feet and pulled her through an opening in a breakwater wall, said Bryan Cheplic, spokesman for Honolulu's Emergency Services Department. The woman banged her knee on the wall but made it to shore.

At the Wai'anae Small Boat Harbor, harbormaster William Aila said he was "hypnotized" by the ocean's motion as Leeward waters rose and dropped 3 feet above and below sea level — a span of 6 feet.

"In 40 years, I've never seen anything like it," Aila said, noting that boat mooring lines tied to the docks strained under the surge of receding and rolling waters.

The surges created a giant whirlpool near the harbor mouth that caught a 42-foot dive boat headed out to sea. At one point, the surge was propelling the craft in the opposite direction, directly at the boats docked in the harbor.

"The vortex just spun us around, and these 6-foot waves were pushing us toward the boats on the dock," said Randy Farnum, who was at the controls of the boat.

He and his boat fought to dodge a catastrophe.

"I didn't think we were going to make it," said Cameron Gaudiz, the boat's divemaster. "We were moving at the same rate of speed as the water — about 6 knots to 7 knots — when Randy turned us around and powered up the jets, and we barely got out of there without hitting any of the other boats."

Police and firefighters were sent to O'ahu beaches to discourage people from going into the water. In Waikiki, police officers drove along Kalakaua explaining the situation over their public address system. At Kuhio Beach, an airborne officer in a police helicopter scolded the only people in the water — 10 surfers.

"The helicopter told them to come back in, but no one did," said Malia Kaleopaa, who rents surfboards at Star Beachboys.

FEW IN THE WATER

Surfer Lori Connelly waited patiently on shore, though, stunned by how empty the ocean was. She said there normally would be nearly 100 people in the water, even on a flat day like yesterday.

"I can sit and wait," she said. "I get to surf every day and you have to respect law enforcement. If they say it's not OK, then I totally respect that."

Nearby, tourist Alan Roberts and his family stood at the water's edge, interested yet unworried.

"We don't get this in Iowa," he said.

His wife, Pamela, took her cue from those around her.

"I'm kind of looking at everyone else and they don't look too concerned," she said.

The earthquake off the Kuril Islands near Japan occurred at 1:14 a.m. Hawai'i time.

The warning center estimated that any tsunami would first hit Hawai'i about 7:20 a.m. and issued a tsunami watch at 2:17 a.m. But even when the center canceled the watch at 5:04 a.m., authorities still worried that strong surges could create a hazard for swimmers, surfers and boaters.

At 5:53 a.m., O'ahu Civil Defense officials issued an emergency alert that interrupted radio broadcasts and appeared on TV screens to keep people out of the water, said John Cummings, agency spokesman. The same message — which told citizens that no dangerous tsunami was generated — was rebroadcast by the National Weather Service at 6:44 a.m., reaching an additional audience tuned into weatherband radios, he said.

The surges transfixed many who saw them.

LARGEST CHANGES

The largest change in sea level reported by the tsunami warning center occurred at Kahului — 60 inches at 9:50 a.m. On O'ahu, the largest rise was 45 inches at Hale'iwa about 8:48 a.m. City lifeguards at Waikiki said the ocean rose and fell 18 inches at a time near the Kapahulu groin.

Charles "Chip" McCreery, director of the Pacific Tsunami Warning Center at 'Ewa Beach, stressed that although the center's data indicated the tsunami would not be "a damaging event," it was large enough that the center considered it a serious, "borderline" event. It was in fact the biggest tsunami to hit the Islands in more than four decades, said McCreery — possibly 100 miles long and traveling in deep ocean waters as fast as 500 mph.

Still, McCreery said, "we felt confident that we weren't going to see any kind of a large, destructive tsunami in Hawai'i, but it was a tsunami that might be a hazard to people right near the shore, and especially to swimmers in the waters and recreational boaters. We had a discussion with Hawai'i Civil Defense about this. The idea was that messages could be issued to alert those along the shorelines about this hazard."

The most dramatic surges were at Nawiliwili Bay on Kaua'i. A 4-foot rush of water at 8:35 a.m. swept over a parking lot at the small-boat harbor, and another overturned a small dock at the Nawiliwili Coast Guard Station, said Chief Petty Officer Marsha Delaney. She said repositioning the dock would cost about $5,000.

At Hanauma Bay, city officials watched the water surge in and out and closed the entire park by 12:15 p.m. Lifeguards there had initially closed the beach, then watched the water level drop by several feet in just a few minutes, then come back.

"The water gets sucked out of the bay, exposing the entire reef, then surges back in," said city Ocean Safety Administrator Ralph Goto. "It's like one cycle of high and low tide, which usually takes six to eight hours, happened in a matter of minutes."

Reach Mike Gordon at mgordon@honoluluadvertiser.com.