Riker said most of the major cities have been destroyed - perhaps LA was spared and the ECON mostly hit the east coast...?
Chuckles and Janeway were at the Santa Monica Pier when she said that. Downtown LA is over twenty miles inland from there. It was called the Hermosa Quake, so I took a USGS fault map and connected the dots between where the Palos Verdes Fault and Compton Thrust Faults meet near Hermosa Beach, then up to the Santa Monica Fault, and finally eastward/inland to the very active and powerful Newport-Inglewood Fault. All the coastal land in between sank 200 meters and became a lagoon. The elevated Palos Verdes Peninsula is now Palos Verdes Island. Long Beach is gone, as is half of my old home town of Huntington Beach, which the Newport-Inglewood Fault runs right under, and the whole area is subject to liquefaction. In truth there is nothing that going to cause a 200 meter subduction of all that land like that, so it's pure Trek fiction, but just playing along. Here's the unmarked fault map if anyone's interested. Captain Pike's old stomping grounds of Mojave would be off to the far right of the map:
Maybe they used neutron bombs or something similar. Relatively limited physical destruction, but with radiation to take care of the cities inhabitants - especially if "salted" with materials that would stay radioactive longer.
Paris and San Francisco survived, we’ve seen them dating back to the original films. No reason why LA didn’t either. Janeway was Bsing about 200m - reefs can’t grow that deep.
An earthquake powerful enough to cause a 200m vertical shift in the crust would hurt a lot more than just LA. Basically, Janeway pulled a number out of the air to sound impressive. Why would she know the history of LA, anyway? Why do all Trek folk know the full details of the history of everything?
It's a longstanding habit of Star Trek to simultaneously insist that World War III was a devastating nuclear conflict that led to the collapse of the world's major governments and hundreds of millions of deaths, and to depict famous cities from real life as having survived just fine into the 24th Century. San Francisco, Paris, New Orleans, London, Boston, Seattle...
Honestly: in my headcanon I just change the 19 in 1990s to 20. After meeting the physically stronger Vulcans in the 2060s and cargo ships getting caught in Xindi raids that the Xindi dramatically refer to as wars in the 2070s and 2080s, an secret extremist group (possibly one that STARTED in the 1990s) wanted to make stronger humans. Didn't Archer say his grandfather fought in the Eugenics Wars? That timeline seems to work. They've had centuries to rebuild: no reason they couldn't do their best to recreate them as they were just on principle.
As a fellow Hoosier, I find it completely believable that Janeway was confused or bullshitting about anything regarding southern California.
World War 3 begins in 2026 according to Memory Alpha. What we will be seeing in Picard takes place two years prior in 2024 per the preview for Season 2.
World War III has already started, according to Fiona Hill: https://www.politico.com/news/magazine/2022/02/28/world-war-iii-already-there-00012340
Writers frequently have a poor sense of scale (cf. George R. R. Martin deciding the Wall was 800 feet tall before realizing how big that really was) so I'm fine with just thinking the VOY writers screwed up with that 200 meters of water claim.
I was curious what the rest of the plaque said, so here's what I was able to determine, to the best of my ability, in case anyone was struggling trying to read it. Thanks to @Lakenheath 72 for mentioning Bunker Hill, as I was having trouble deciphering that part.
They got the founding date wrong on the plaque. El Pueblo de la Reina de Los Angeles (The Town of the Queen of Angels) was officially founded on September 4, 1781, so late 18th century rather than 19th century. And of course the region had been settled by indigenous tribes for nearly 10,000 years at that point.
It's not smog, it's... um... haze! It's haze, from releasing a wonderful chemical in the atmosphere periodically that helps prevent lung cancer. Like putting fluoride in the water. Yeah. That's the ticket.