State officials, emergency responders and earthquake analysts warned this week that Long Beach and other low-lying beach cities of Southern California would be hit the worst if a large tsunami were to strike the coast.
Rare but plausible, the worst-case scenario would be a 9.1 earthquake off the Alaskan peninsula causing the local region’s sea level to suddenly rise five to 10 feet within just a few hours, according to a study released last September by the United States Geological Survey (USGS).
The fast-moving wave would cause major flooding in low-lying areas, such as Long Beach and nearby cities in Orange County, where waterfront homes and commercial development are most vulnerable to tsunamis because of the lack of cliffs. Strong currents would also devastate harbors and marinas.
Luckily, people within the tsunami-inundation zone would only have to walk a few blocks to reach dry land, according to the study.
Still, experts say residents and visitors should be prepared for such an event that the study estimates would force some 750,000 people to be evacuated statewide and cause one-third of the boats in California’s marinas and harbors to be damaged or completely sunk, resulting in $700 million in losses. The study estimates the state’s total damages, including business interruptions, would be $5 billion to $10 billion.
“It is a very plausible event … it’s not that frequent, but it’s also not really crazy,” said Lucy Jones, a USGS scientist who headed the study, known as the Science Application for Risk Reduction (SAFRR) Tsunami Scenario.
Jones, who also led the first “ShakeOut” earthquake scenario in 2008, spoke during a lecture on tsunamis at the Aquarium of the Pacific in Long Beach on Monday, March 24. The sold-out event, which included a panel of experts, coincided with Tsunami Preparedness Week. The event also took place just days before the 50th anniversary of the Great Alaska Earthquake, which triggered a tsunami on March 27, 1964, killing a total of 16 people in California.
About three years ago, teams of scientists, first responders and other experts began modeling the tsunami scenario after the Alaska earthquake. The study, however, was later extended to take into account the 2011 tsunami that was triggered by the Tohoku, Japan earthquake that resulted in the Fukushima nuclear disaster. That tsunami didn’t produce much flooding in California but caused millions of dollars in damages to marinas, particularly in the Crescent City Harbor, according to experts.
A tsunami causing the sea level along California to suddenly rise five feet is rare and only happens about every 100 to 200 years, Jones said. However, she noted that such an event would damage harbors and marinas, spreading debris throughout the area. Jones said a tsunami would also impact the ports of Long Beach and Los Angeles, which receive 40 percent of the nation’s imports.
Patrick Lynett, an associate professor at USC’s department of civil and environmental engineering who analyzed ocean currents for the study, said large vessels, such as container ships and cruise liners, will be “mostly safe.” He added, however, that it would cause major disruptions at the ports because of strong currents and smaller boats at marinas would be the most damaged.
“Along the West Coast in 2011, we had a lot of damage in harbors, but you didn’t have a lot of flooding,” Lynett said. “The reason that you have all this damage in harbors is because, even if the water doesn’t go very high, it still goes very fast.”
He said the worst place for a boat to be during a tsunami is navigating in and out of the harbor “gates,” where there would be the strongest currents.
“That’s a particularly bad area to be,” Lynett said. “You really don’t want to be a ship making your way through the gate because the currents there are tremendously strong and they’re swirling … If you have time to get out of the harbor before the wave comes, great, get out. If you don’t, stay in the harbor, tie your boat up, straighten the lines and just leave. You don’t want to be in the water while the tsunami is happening.”
He added that the Long Beach breakwater won’t make much of a difference in a tsunami, since it’s “quite permeable” and the displaced water would still rush through it.
Coastal cities across the state are currently preparing evacuation plans in the event of a tsunami while maritime officials are working with new maps developed by the California Geological Survey (CGS) that outline maximum tsunami-inundation zones.
Rick Wilson, senior engineering geologist for the CGS, said the study concluded that neither of California’s nuclear power plants would likely be damaged by such a tsunami. However, he said a large tsunami still would impact other power plants and facilities. Wilson added that the State has posted blue signs on some beaches and coastal communities to make people aware that they are in a tsunami-inundation zone.
“It doesn’t happen often, but when [a tsunami] does happen, especially when there’s a high tide, we see the potential for more flooding,” Wilson said.
In Long Beach, the inundation zone extends from the Queen Mary to just south of Ocean Boulevard. Under the scenario, areas submerged would be the Aquarium, the Long Beach Convention Center, Shoreline Village, the Pike and the Alamitos Bay Marina.
Jones said more than 20,000 residents in Long Beach who live in the inundation zone would have to be evacuated, adding that the zone includes some schools, daycare centers and adult centers that should have adequate evacuation plans in place.
The National Oceanic and Atmospheric Administration (NOAA) has two hours from the time the earthquake hits to issue a tsunami warning, she said. Thereafter, residents have two hours before the tsunami touches down to evacuate the area, which in most causes means moving about three blocks inland.
“If we handle the warnings right, nobody will die,” Jones said. “… You survive a tsunami by not being in a tsunami.”
Jeff Reeb, director of emergency management for the County of Los Angeles, said it’s important to encourage the public, particularly people with disabilities, to be prepared for a major tsunami in order to minimize any loss of life.
He said people should stay connected through cell-phone notification systems, such as Alert LA and Nixle, as well as social media. Reeb added that residents and business owners should learn the appropriate steps to take when tsunami warnings come forward, such as preparing go-to kits with important records and other valuables.
“What we encourage everyone to do is, of course, be aware of your surroundings, whether you’re visiting our Aquarium or down in one of our coastal areas,” Reeb said. “When the warning comes, it is time to move. Whether you walk or run or ride, it’s time to go.”