While areas like the Los Angeles coastal plain, harbors and river entryways are vulnerable to tsunamis, "much of California is less vulnerable to the kind of tsunami wreckage caused today in Japan because the state's coastline is generally steeper," says Steven Ward, a research geophysicist at UC Santa Cruz, speaking to the Sacramento Bee. In 2004, researchers at USC's Viterbi School of Engineering pointed out the vulnerability of ports of Los Angeles and Long Beach to a tsunami, , while there's also been criticism in how prepared the US to issued tsunami warnings to residents. You can sign up to get alerts on your cell phone about warnings via LA County's Alert system. UPDATE: More on the LA area risks from a 2010 California Planning & Development Report story, now quite prescient: "Approximating maximum inundation for a worst-case scenario tsunami, the line washes over all of Newport Bay and Marina del Rey, wipes out parts of downtown Santa Cruz, and makes half of Seal Beach disappear. Some of the state's most fabled real estate from La Jolla to Malibu to Montecito would wash out with the tide. It would yet again pummel Crescent City, itself the victim of the nation's most destructive and deadly recorded tsunami, a 20-foot wave that struck on Good Friday, 1964."