With a number of close calls from distant tsunamis, and a branch of the Newport-Inglewood fault about one mile offshore, the city of Newport Beach has spent the last several years preparing for tidal waves.
Officials have created an evacuation plan for low-lying areas, installed sirens along the coast and coordinated with Newport Elementary School on the Balboa Peninsula, in case waves come during school hours.
To teach residents about the dangers, they've tried posting information online and on signs, by printing brochures and offering courses through its Community Emergency Response Team.
"It's on a lot of peoples' minds, and we've been getting a lot of calls," said Katie Eing, emergency services coordinator for the Newport Beach Fire Department.
Based on predictions from USC engineers, Newport Beach areas near the water that are less than 32 feet high would be susceptible to a tsunami "run up." That's the surge of water that engulfs land, like the one that swept across parts of Japan and has been replayed on cable news shows over the past week.
"Newport Beach is extremely vulnerable because it's extremely flat," said Costas Synolakis, a professor at the USC Tsunami Research Center.
The areas at risk include the Balboa Peninsula, the harbor's islands and bayfront locales, West Newport Beach, some parts of Corona del Mar and parts of the Back Bay shoreline.
About 40,000 people live in those areas, Eing said.
Many of them tried to flee the Balboa Peninsula in 2005 when a 7.2 earthquake struck off the coast of Northern California. Officials issued a tsunami warning, more serious than the advisory sent out March 11.
Today, based in part on the 2005 event, officials anticipate congestion on the Peninsula, with people trying to leave in cars. They've modified evacuation procedure, Eing said, and would now keep all the lights green for outbound lanes.
If there's a warning issued by the West Coast and Alaska Tsunami Warning Center, Newport Beach police officials would sound the city's three new emergency sirens along the coast. The goal of the sirens, along with other emergency notification systems, is to get people to turn on their televisions or radio for more information.
"It doesn't necessarily mean run for hills," Eing said.
If they had sirens in 1934, Newport officials certainly would have sounded them. A 9.8-foot wave injured four people, destroyed several cottages on the peninsula and washed away pavement, which isolated some residents, according to an Orange County Grand Jury report on tsunami dangers.
Newport is also part of AlertOC, an automated countywide emergency notification system that calls residents and businesses. All city landlines were called about 4 a.m. March 11 to warn of the tsunami.
Officials can also activate the emergency broadcast system, which streams information across television screens and makes announcements on the radio. Eing said the city uses K-Wave 107.9 for radio announcements.
Residents would be instructed to indeed head for the hills in the case of an extremely strong earthquake near the coast. If the quake is so strong that it knocks people off their feet, Eing said, they should evacuate the low-lying coastal areas.
Newport sits directly atop the North Branch of the Newport-Inglewood fault, while the South Branch runs parallel to the coast about one mile offshore.
A local quake poses less of a tsunami risk than one in Alaska, said Jose Borrero, an associate at the USC Tsunami Research Center.
Newport-Inglewood is a "strike-slip" fault, which means that its plates move laterally, while some in Alaska move vertically — a motion more likely to produce tidal waves.
One risk here is from an underwater landslide causing a tsunami. The Newport Submarine Canyon extends seaward from around the Newport Pier, and officials say they have found evidence of slides there.
But they don't have enough data to be able to predict any of those scenarios, Borrero said.
"It's such a big, giant unknown," he said.
Most of the damage from a Newport-Inglewood quake would be on land, experts say.
A moderate quake here could cause significant damage and loss of life largely because of the coast's dense population and loose soil. Coastal areas are prone to liquefaction, a process in which the soil turns mushy from the extreme vibration.
When a 4.6 temblor in 1989 struck under the site of the Newport Dunes Beach Front RV Park and Marina, residents were briefly shaken, but no major damage was reported.
Students ducked under their desks at beachfront Newport Elementary, inside the flooding-prone, one-story buildings.
Today, in case of a tsunami, officials have a plan to evacuate students to the nearby Our Lady of Mount Carmel Church, and to have them wait on the second floor. If there is enough time, Eing said, school bus drivers would shuttle them to higher ground inland.