Tsunamis present a risk for the entire Californian coast. But should a major strike be bad?
A single tsunami probably does not cause the worst case for each region. But in total, more than 680,000 Californians are in a risk area of tsunami during the day. And in all, 12.6 billion dollars of damage is possible in the 20 coastal counties and Bayside of California – a figure that does not include damage to ports, ports, roads, essential installations or other infrastructures.
There are two main types of scenarios for a tsunami. The first, a “distant” tsunami, comes from far away, like the one generated by a major earthquake in Alaska. This would provide an extensive warning – six hours for the and five hours for San Francisco – but could produce the highest level of flood for the major state expanses.
Then, there are tsunamis “close to source”, which can wash on the ground as little as 10 minutes after an earthquake nearby – leaving a short time for an opinion or an evacuation.
Here are some scenarios for different parts of California. Unless otherwise indicated, the figures come from the California Tsunami program, which is managed by the California Governor’s Office of Emergency Services and the California Geological Survey.
South California
Tsunami distant source: More than 350 people could die or be injured along the southern coast of California if people are waiting to evacuate half an hour after an official evacuation warning. This includes around 200 victims in the County of Los Angeles, about 80 in the County of San Diego, 60 in the County of Orange and about a dozen in the county of Ventura.
An earthquake of hypothetical magnitude 9.3 of Alaska – similar to the scale of the temblor generator of monstrous tsunami from 1964 – would offer six hours of warning; Chile’s great tremors could provide 13 hours of warning.
The tsunami with a projected maximum distant source could bring waves of 15 feet above the average level of the sea to Marina Del Rey, the pier of Santa Monica, Naples and Alamitos Bay; 14 feet elsewhere in other long beach parts; 10 feet in Manhattan Beach, San Pedro and the ports of Los Angeles and Long Beach; 9 feet in Malibu, Redondo Beach and Palos Verdes Hills; And 8 feet at Leo Carrillo State Beach.
These estimates were published by California Geological Survey and published in the Los Angeles risks attenuation plan.
Estimate of damage to distant source tsunami: Over $ 1.4 billion.
Tsunami close to the source: Los Angeles could see a tsunami move from its source to the coastal areas as little as 10 or 15 minutes, warns the city’s tsunami plan. According to public documents, depending on the fault that breaks, or when an underwater landslide is triggered, there could be heights of tsunami generated locally 30 feet in Avalon on Catalina island; 24 feet with Hills Verdes; 18 feet in two ports; 11 feet at Redondo Beach; 9 feet in Malibu; 8 feet at Long Beach and the pier of Santa Monica; 7 feet at Manhattan Beach and San Pedro; 5 feet at Marina Del Rey; and 4 feet at Leo Carrillo State Beach.
In the city of Los Angeles, officials say that the most catastrophic scenario would involve an underwater landslide triggered by an earthquake, because “we cannot know that this landslide would occur until the arrival of the wave,” said Jon Brown, deputy director of the city’s emergency management service.
The other areas of the county of the with considerable vulnerability include ports, as well as San Pedro and Long Beach. The city of Los Angeles has around 23,000 inhabitants in the Tsunami dangers area. In Long Beach, the number is 31,000.
Central coast
Tsunami distant source: More than 230 people could die or be injured if people wait half an hour to evacuate after an official warning. The County of Santa Cruz could see more than 130 victims; The County of San Luis Obispo, about 80 years old. The tolls of estimated potential victims could be 16 in the county of Monterey and seven in the county of Santa Barbara.
Estimate of damage to distant source tsunami: Over $ 3.5 billion.
Tsunami close to the source: The counties of Santa Cruz and Monterey could see a tsunami in the minutes following underwater landslides triggered by the earthquake, according to the two counties. “Even a moderate earthquake could cause a local source tsunami from the sliding of underwater land in Monterey bay,” according to public documents.
A tsunami close to the source could bring waves up to 15 feet above the average sea level in the city of Marina, at 9 feet on the Salinas river; 8 feet on the Pajaro river and the city of Sand, just north-east of Monterey, and 6 feet in Mosse Landing, according to data published in the risks attenuation plan of the county of Monterey.
Such devastation would not be unprecedented. A large earthquake in the Santa Barbara region in 1812 led to a tsunami “which has destroyed many coastal villages and destroys ships in the port”, according to US Geological Survey.
And 7 -foot waves resulting from a tsunami in 1927, generated by an earthquake about 5 miles west of the Coast of Santa Barbara, according to California Geological Survey.
The USGS said there were evidence of submarine landslides abroad from Santa Barbara dating over 160,000 years, suggesting that “future earthquakes could cause large underwater landslides and devastating tsunamis”.
Bay
Tsunami distant source: More than 1,300 people could die or be injured if people wait half an hour to evacuate after an official warning. About 500 of them could be in San Francisco; About 300 each in the counties of San Mateo and Marin; Nearly 200 in the county of Alameda and 33 in the County Costa. Just north of the region, in the county of Mendocino, five people could die or be injured in this scenario.
A hypothetical tsunamis generation earthquake in Alaska could provide 5 hours of warning; One from Chile could provide 13 hours of warning.
The tsunami with a projected maximum distant source could lead to a 32-foot tsunami above the average level of the sea in the ocean beach in San Francisco; 31 feet in Pacifica in the county of San Mateo; 27 feet in Bolinas in the county of Marin; 18 feet in Alameda; 14 feet in the Sausalito and San Francisco water park; 13 feet on Alcatraz Island; And 11 feet in Richmond and Treasure Island, according to the California Geological Survey.
Estimate of damage to distant source tsunami: Over $ 6.5 billion.
Tsunami close to the source: In northern California, a tsunami close to the source could generate a 9-foot tsunami above sea level in Bolinas; 8 feet in Pacifica; 7 feet in Sausalito; 6 feet at Ocean Beach; 5 feet in Alameda; And 4 feet on Alcatraz Island, Treasure Island, Aquatic Park, Redwood City and Richmond.
Northern coast
Cascadia scenario: Given its proximity to the Subduction Zone of Cascadia, the county of Del Norte – the northern coastal region of the State – is perhaps more exposed to the risk of tsunami than any other part of California. If people are waiting 10 minutes after an earthquake to evacuate – the tremors itself would be the warning to flee – more than 3,150 may be killed or injured by the tsunami in the county of Del Norte, and more than 720 would be at risk in the neighboring County of Humboldt.
The floods could reach up to 30 feet above the average tide along the outer coast of Humboldt bay and the Eureka region, and up to 50 feet to Crescent City.
“A large earthquake generated by the Cascadia subduction area could create waves twice as important as the 1964 event, in particular at Crescent City,” said Rick Wilson, a former Tsunami program chief of California Geological Survey, in a statement.
Damage estimates: The County of Del Norte, which houses Crescent City, could see more than a billion dollars in damage. Humboldt County, which houses Eureka, could see $ 22 million.
