Yet Another LA Shaker

Eleven days ago we had a magnitude 4.4 earthquake and I wrote about it and earthquakes in general. The tl;dr version: “Earthquakes are scary and can be deadly.”

Tonight we’re shaking again, this time a little bit more “briskly”, shall we say. It probably wasn’t quite up to shaking “violently”, at least not from the reports I’ve seen yet, but it’s early. This only happened less than an hour ago.

Tonight’s preliminary reading was a magnitude 5.1 earthquake in La Habra, just south of the Los Angeles – Orange county line. (It was initially reported as a 5.4, but the instant readings usually are corrected down a bit as more data is received.) A 5.1 shake is still a long way from “The Big One” (it’s coming folks, really, really) but it’s big enough to cause some damage.

So far there are only reports of some “moderate” damage with no details on what that means, other than one report of a road being blocked by a rock slide and a local fire station that’s been damaged. All of Disneyland’s rides had their safety systems kick and and stop the rides, and now they’re shutting down the park early. A few pictures of pantries and shelves dumped on the floor are popping up. We hope that there aren’t any injuries, but a 5.1 is strong enough to potentially cause them. I wouldn’t be a bit surprised if by morning there aren’t at least a few dozen homes and buildings with some significant damage.

The other bit of news that’s coming out early in this one is that the earthquake occurred right on the Puente Hills thrust fault, which is the fault that was responsible for the 1987 Whittier Narrows earthquake. That was a 5.9 quake that killed eight people, injured hundreds, destroyed 123 homes and over 1,000 apartments, damaged over 500 homes and 2,000 apartments, with a total of over $350 million in damage. Even more importantly, it’s the fault line that runs straight under downtown Los Angeles. The downtown with all of those really, really tall skyscrapers that have never truly had the earthquake building codes tested much out in the real world.

One might be tempted to say, “Well, so what? This wasn’t a 7.5 or an 8.5 quake on that fault and all of those buildings didn’t get tested. It was just a 5.1 in La Habra.” The thing is, it’s a known phenomenon that some earthquakes, particularly quakes in the high 4’s and 5’s, are “pre-shocks,” the opposite of aftershocks. It’s not a huge likelihood, but it’s sure enough to make the USGS, Cal Tech, the fire, police, emergency services, the city emergency command posts, and everyone else involved stay on their toes tonight. The odds drop off by the hour, and they’re sort of long to begin with. On the other hand, if it does happen, we’re all gonna be in a world of hurt.

The other thing that I’m noticing with this quake (and the one eleven days ago) is how much information is available instantly on social media, particularly Twitter. CalTech and the USGS have bots set up that you can follow (I do) which will tell you immediately the time and location and magnitude of any quake, with a link to a map. That bot has been lighting up Twitter, with over twenty aftershocks in the last hour.

I also follow the LA Times on Twitter, as well as several news reporters and stations. When something like this happens, you start finding out about it far, far faster than you ever did before. (Remember the shooting at LAX last year where the TSA agent got killed? The first news reports of that were from Twitter, particularly since there were some celebrities near the site of the shooting and they have LOTS of followers.) You need to use some common sense in interpreting the raw information and know who to trust and who to take with a grain of salt. Having said that, it’s astonishing to me to see how fast information gets out if you know who to follow and get it from.

Finally, the Angels and Dodgers were playing a pre-season, exhibition game at Dodger Stadium when the quake hit. Listen to one of the great voices of the game, Vin Scully, describe it. The man’s got a story for every occasion, and he’s always calm and comforting. I swear, he wouldn’t change that tone if the alien mothership landed in Dodger Stadium. And he would have a story that was relevant for the occasion.