The good news about the latest new tsunami study, says Lucy Jones of USGS, is that three quarters of the California coastline is cliffs. The not so good news is that the remaining, low-lying coast is home to many people and some of the most valuable land in the state. The bad news is that a hypothetical but plausible tsunami scenario from a 9.1 earthquake in the Pacific Ocean off Alaska would wreak a lot of havoc in Southern California. The maps show serious inundation in Long Beach and Newport Beach. Something like 750,000 people in the state would need to be evacuated, including 90,000 tourists and visitors. One-third of the boats in California's marinas could be damaged or completely sunk, the study says. If it all seems a little remote, remember that the big Japanese quake and tsunami in 2011 did between $50-$100 million damage along California's shores. The major Alaska quake of 1964 (magnitude 9.2, the largest ever recorded in the United States) also spawned a tsunami that did damage in California.
The experts refer to the waves from Japan and the kind that could be triggered by an undersea quake off Alaska a "pan-Pacific tsunami." That scary, colorful map of the Pacific you have seen being spread around Facebook as evidence of radiation spreading to the U.S.? That's actually the tsunami forecast map from the 2011 Japan quake. (Nothing to do with radiation.)
Says Jones in a release accompanying the report:
In order to effectively protect communities from tsunamis, we must first know what to plan for. By starting with science, there is a clearer understanding on how tsunamis function and their potential impacts. The scenario will serve as a long-lasting resource to raise awareness and provide scientifically-sound and unbiased information to decision makers in California and abroad.
Here's the release and the full report as a big PDF file. The U.S. Geological Survey's Science Application for Risk Reduction (SAFRR) Tsunami Scenario is a joint project of USGS, the California Geological Survey, the California Governor's Office of Emergency Services, the National Oceanic and Atmospheric Administration, other agencies, and academic and other institutions.
Previously on LA Observed:
Japanese tsunami debris drifting across the Pacific
Tsunami surges (gently) up Ballona Creek
What a tsunami looks like on the ground
Crescent City tsunami in time lapse
Tsunami damage mounting in Crescent City, Santa Cruz *
8.8 quake strikes Chile, tsunami warnings in effect *