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7.1 magnitude earthquake strikes Southern California (latimes.com)
288 points by t23 on July 6, 2019 | hide | past | favorite | 167 comments

> This quake was larger than the destructive 1994 Northridge quake, which measured 6.6 magnitude.

This isn't entirely accurate. While it's "score" was higher, the magnitude doesn't account for things like the type of fault, the type of movement, the depth, the soil, the duration of movement, etc.

Northridge was far more severe than this one, with an "apparent magnitude" greater than 9.

Don't get me wrong, this one sucks for all the people affected, no doubt, but as someone who lived through Northridge very close to the epicenter, it's sort of personal to me.

There are earthquakes, and then there is the ground shaking that results from earthquakes.

The magnitude scale that is most used is an expression of the total energy release in the earthquake is called the 'moment magnitude' or 'work magnitude' because it's measured in those units (Newton meters or dyne-cm). It is calibrated to be similar to the original Richter scale, which was an empirical, I believe unitless, scale based directly on seismometer readings. If someone credible says that an earthquake is a 3 or a 7 or something, they are almost certainly referring to the moment magnitude. The 1989 Loma Prieta event was a M 6.9 event, Northridge was M 6.6 or 6.7.

There is another measure called the 'intensity' that you may be referring to with the 'apparent magnitude' reference. This is a non-quantitative, basically ranked categorical description of the amount of ground shaking and subsequent damage that occurred. The most common intensity scale is the Modified Mercalli intensity scale; it is usually (and correctly) denoted in Roman numerals. The Wikipedia page for the Mercalli scale [1] is good, however I prefer [2]. The intensity has a sort of tree-falling-in-the-woods element to it: the categories are based on how people and the built environment respond to the earthquake, so did earthquakes in the 4.6 billion years before humanity have intensities? They had magnitudes.

Quantitatively, ground shaking is measured as 'peak ground acceleration', a force, usually compared to gravity 'g' (i.e., 9.81 m/s^2), as 'peak ground velocity' which is a velocity (m/s), or as 'peak ground displacement' which is a distance.

The intensity of an earthquake will be related to the peak ground acceleration and velocity, as well as the duration of the shaking. These are functions of both the earthquake properties (magnitude, faulting style, depth) as well as the properties of the ground in the region of the earthquake, and the distance from the earthquake (as the amplitude of the waves decreases with distance). Solid rock does not shake nearly as much as loose or wet sediment, for example, and some geologic basins that are deep pockets of sediment surrounded by bedrock can amplify earthquake waves and make the shaking locally much worse than it was elsewhere, even closer to the earthquake. This was a big deal in Loma Prieta, for example--the damage in Oakland, built on water-saturated sediment, was worse than in some of San Jose, or in my (current) house in the Santa Cruz mountains just a few km away (I was safely dodging tornadoes in Tulsa at the time).

[1]: https://en.wikipedia.org/wiki/Modified_Mercalli_intensity_sc... [2]: https://www.mcsweeneys.net/articles/levels-of-the-mercalli-s...

There's also a noticeable difference in waves. Some quakes hit you with a lateral motion (which, I presume magnifies any possible liquefaction). Some hit with a rolling motion (which really wreaks havoc on masonry). And some hit you with both (those are the ones where you hope the building doesn't collapse on you).

Northridge was violent beyond belief. I lived less than a mile from the epicenter at the time. I remember it distinctly because I stayed up coding all night. It hit at 4:31 AM (the image of the digital clock on the shelf is seared into my mind). It felt as what I can only describe as a train going through the house.

I was nearby too in the valley and running for the doorway was like trying to run in a bounce house. Also, the doorway is no longer recommended: https://earthquake.usgs.gov/learn/topics/megaqk_facts_fantas...

I still had my analog clock set at 4:31 for months after Northridge, it kind of served as a reminder to me that quakes happen, plus I was too lazy to retrieve the batteries that rolled under the bed .. but yeah, 4:31 is burned in my mind too. Occasionally I'll be up in the middle of the night and 4:31 will roll past, and I'll lay there thinking about that quake.

I'll add a bit to my story...It actually involved levitation...

As I said, I was up coding all night. At the time I had a U-shaped desk flanked on all sides by bookcases full of books. Lots of databooks filled these shelves (for software guys: These are books published by chip makers containing their catalog of chips and technical details on each one).

I was working on a the microprocessor code for a high power motor control. The hardware, 100A power supply and test equipment where all on my desk, turned on and operating. I was using a very large ceramic wound resistor in a bucket full of ice as a test load. The bucket was on the floor and connected to the motor driver via very large conductors (think jumper cables).

At 4:31 AM I felt a single jolt. I know because that's when I looked up at the digital clock up on the shelf immediately in front of me. It was a Radio Shack clock with red LEDs for the digits. It was part of their home automation system, with buttons on top to turn on and off various satellite plugs, lights, etc.

The jolt felt like The Hulk shoving the house or something like that. One sharp short jolt. My first thought was "this is going to be bad". I had been in a couple large quakes but this jolt had a different feel to it.

That's when it started. And what was bad about it is that the vertical component was significant. Well, significant enough to launch me and every single book and object on my bookcases straight up into the air. The compressed air spring in my chair acted like a pogo stick. I literally got launched upwards, I'll guess at least a foot, if not more.

My last memory of this portion of the event was floating in space with all of my books in the air at the same time. It was very, very weird. Power went out, I fell to the ground and so did everything else around me. The shaking was violent, as I said before, like a train going through the house.

Thankfully the motor driver wasn't hot because I was not driving the load at the time. It ended-up on the floor buried under a pile of National Semiconductor databooks. That would have easily been a fire had the thing been hot and power not gone out.

I later found a massive 8 inch drive that was on a shelf across the room landed just inches from where I fell to the ground. That thing could have sent me to the hospital. Amazing.

I still have the clock somewhere.

(very off topic) @robomartin - Would you be ok to email me (justin@postgresql.org) re that Open-Source Leg project from a while back?

Can't see your contact details anywhere, so using a comment here instead. ;)

Great! :)

It's also larger than the 1989 Loma Prieta earthquake that destroyed a lot of San Francisco, which was 6.9.

A lot of this also has to do with how close to populated areas the earthquake is, and if the same quake happened today, the damage would be much less due to better construction.

Better construction is real. I work for a medical institution that is spending close to $1bln to build a new hospital from scratch because they found it cheaper than to do yet another earthquake retrofit.

destroyed a lot of San Francisco

That's overstating things by quite a bit. There was severe damage and fatalities but 'destroyed a lot of San Francisco' was 1906, an estimated 7.9 followed by fires.

The fires did by far the majority of the damage.

  destroyed a lot of San Francisco
It destroyed hardly any of San Francisco (almost nothing outside the Marina), given that the epicenter was three counties away.

Um, no. LP caused extensive damage in small sections of San Francisco, but the two eqs are nearly the same intensity.

PS: I lost my proverbial "I survived the Loma Prieta in San Jose" t-shirt. Lost half a swimming pool, bookshelves, dishes and so on... our furniture was anchored to the wall studs and computer monitors and other electronics were industrial Velcroed to surfaces.

In terms of magnitude, a 7.1 earthquake shakes 1.6 times as hard as a 6.9 earthquake, due to the scale being logarithmic.

No, the magnitude is not a measure of shaking. There's a comment elsewhere in thread that talks about some of the details.

Note that Loma Prieta is just north of Santa Cruz, over 60 miles from San Francisco.

Not sure how to compensate for distance, but my gut feel says that's about equivalent to a 5.9 in SF itself?

Northridge knocked me out of bed and I woke up on the floor.

Same. And I was in a bunk bed. :(

Almost killed my friend, who just happened to move his bed away from the bookshelf the day before. The bookshelf smashed to the ground right where his bed had been.

We also had to dig my grandparents out of their house with shovels.

Please tell me you dug them out alive?

Yes. :) After the initial shock, they barricaded themselves into the storage room behind the garage, because there was a pull out couch and a phone in there. But we couldn't call them because another phone in the house had been shaken off the hook. So we drove down there as quickly as we could and when we got there everything inside was rubble, the chimney was just a pile of bricks, etc. (although the house itself was still standing).

We got shovels and started digging, calling out their names. Finally got the back and found them sleeping in the pull out sofa! We packed some of their stuff and took them back to our house since we had minimal damage (despite being thrown from bed) and then went back later to survey the damage.

At that point people in the larger multi-family buildings had all evacuated and set up tents in the median strip on the main street (Ventura Blvd). Many of those buildings were condemned.

Simi Valley checking in, everything on the floor! TV, dishes, CDs.

Northridge was horrendous, but I personally didn't suffer any damage other than a book-end falling off my properly secured shelves, and my cat taking a massive piss right in the middle of the floor. My roommate and his girlfriend survived the mirror over their bed crashing down on them somehow, but other than that .. no worries. A well-built house.

My neighbours - well, lets just say that by the time I got my senses together to go outside and inspect things, they'd already packed all their shit and their kids into the SUV and were moving back to Oklahoma that instant, no time to wait - they GTFO'ed out of California... their house wasn't even that damaged, apart from its chimney laying in the street, like every other brick chimney in the neighbourhood ..

Northridge was wild. I'll never forget the feeling of walking around Hollywood that morning, looking at the kitchen and toilet sections of apartment buildings that had their walls stripped off them, like some bear had ripped open a beehive to get to the goods ..

> the mirror over their bed crashing down on them

I could never sleep under a mirror for exactly that reason.

They were young, and had their reasons. :)

My dad was in Northridge for two days to film on Jeopardy and was hit by the quake. he said he saw the pool sloshing around. As a contrast, I've been on NorCal for 28 years and haven't experienced anything larger than a 4.5 or so.

I was in an earthquake in DC in 2011 that, while lower on the Richter scale, felt way worse than the one that happened in LA today.

I didn't even feel the one yesterday either.

Was giving my daughter a bath when it started. At first I thought I was fainting, because it was a really slow rolling motion like I was on a boat. Then noticed the shower door moving.

My daughter kept saying she wanted to go see the earthquake. I think she thought it was outside.

Same about the fainting. I was standing in line at Target on the 4th, and I could have sworn I was gonna pass out there and then until the lady behind me asked if anyone else had felt that. Then I noticed the aisle signs swinging!

I always look for liquid surfaces, water in a glass etc. They will be busy oscillating much before the body makes sense of whats going on...

Ah yes, the Jurassic Park method of shake detection.

> “The mirror shaking was easy … put a little vibrating motor in and shook it.” Lantieri said. “But the water was another story. It was a very difficult thing to do. You couldn’t do it. ”

> “In order to replicate that for the eventual shot, they “fed a guitar string through the car, down to the ground, and then I had a guy lay under the car and pluck the guitar string,”


Wow, great anecdote hah I never would have thought that’s how they did it

I always get the names of the different types of quakes confused, but this one was definitely a lot of long slow movement. I have felt some that were more like loud bangs and big jolts, but this one was just like being on a boat.

I wonder if the P Wave is what gave you that feeling.

These are surface waves, which have a much greater amplitude on the earth's surface than P-waves (which are faster). It's pretty unlikely that anyone can feel P-waves unless they are fairly close to the epicenter. P-waves are also basically a very short pulse; the S waves, which come later, last a bit longer, but also may have relatively low amplitude, and then the surface waves come last and cause the most perceptible (and damaging) ground motion.


I definitely felt the p waves in the Seattle quake about 18 years ago. It felt like an initial whump, followed by the shear shaking a moment later.

LA Times published an article earlier today about how yesterday's quake may have increased the strain and could lead to a larger one like this: https://www.latimes.com/local/lanow/la-me-ln-did-california-...

More info in this article (linked to from the one above): http://temblor.net/earthquake-insights/southern-california-m...

When you go to that area and stand on one of the mountains -- say, on the west ridge of Death Valley -- you can clearly see how the region is a bunch of vertical columns of continental crust that have toppled over, like dominoes. If I call correctly, as the North American plate is pushed up, it gets pulled apart (because the Earth is spherical?) and the cracked pieces fall onto each other. The valleys in between fill with sediment over time, but get deeper also as the mountains roll over further.

Point is, I wonder if this was the sound of Badwater Basin (lowest point in North America) getting a little bit lower...

Close, but not exactly.

Today's earthquake was a strike-slip earthquake, where two parts of the crust slide laterally by each other on a fault plane inclined close to vertically in the crust. The fault is probably oriented NW-SE [1], parallel to the San Andreas fault, although from the pattern of energy release from the earthquake (known as the focal mechanism[2] or moment tensor[3]) it also could be on a NE-SW oriented fault, with the direction of shear being the opposite. Because this was a strike-slip earthquake on a vertically-inclined fault, there won't be more than a few cm of uplift or subsidence of any parts of the earth's surface.

The domino-style faulting that occurs in the Basin and Range of the US, basically from Owens Valley to Salt Lake City, is an expression of 'normal faulting' (rather than strike-slip faulting). Normal faults are inclined from the horizontal, and the block of crust above the fault slides down the fault, like down a ramp. After a lot earthquakes (hundreds to thousands of M6+ earthquakes) the blocks have rotated on a horizontal axis quite a bit, so that they are no longer upright [4]. Furthermore, and quite importantly, as a result of this faulting, the crust (or at least the upper crust where the faulting happened) is both thinner from top to bottom than it was previously, and wider than it was previously--we say that the crust got 'extended' because it is horizontally lengthened/widened. You are absolutely right that Death Valley is forming in this kind of environment.

There are two main reasons for crustal thinning and extension. One reason is that the boundary of that part of the crust moved away, so the crust stretched or extended to fill the gap. The other is that the crust was too thick and high, so it spread out. The continents are kind of like rafts of granite floating on more dense, hot, ductile rock below (the mantle). The density contrast between the lighter crust and the mantle is sort of like icebergs floating in sea water, so most of the continents are below the surface of the ocean basins. When a big mountain range is built that gets high, it also has to have a thick root to support its surface elevation, like the undewater part of an iceberg. However, the crust isn't always strong enough to support a big mountain range for a long time, and so it will break apart under the force of gravity and spread out laterally, reducing the gravitational potential energy contrast between the (formerly) high mountains and the surrounding lower elevation crust.

It is thought that in the western US, both processes (the moving boundary condition, and the gravitational collapse and spreading of the crust) have been the cause of the crustal extension that produced the domino-style block faulting. The big collapse was probably during the Miocene, say about 15 million years ago, which produced a lot of the faults and smaller mountain ranges that we see today. Many geologists think that California was one or two hundred kilometers closer to Colorado, and the area that is now Nevada and western Utah was narrower and much higher--say a mean elevation of over 10,000 feet. This has been nicknamed the 'Nevadaplano' in reference to the Altiplano of Bolivia and Peru, which is an analogous geologic feature. I think that there is also a slight component of extension between the North American and Pacific plates at this latitude, i.e. the Pacific plate is mostly sliding by North America on the San Andreas and parallel faults, but it might also be moving away from North America (i.e. Kansas) at a few mm per year.

[1]: https://earthquake.usgs.gov/earthquakes/eventpage/ci38457511...

[2]: https://en.wikipedia.org/wiki/Focal_mechanism

[3]: http://seismo.berkeley.edu/~rallen/eps122/lectures/L12.pdf

[4]: https://en.wikipedia.org/wiki/Tilted_block_faulting

You can see something similar in the Valley of Fire in Overton, Nevada. If you go on a Fire Canyon Road and look south, you can see the green hills in the back with red rocks in the middle and white in the foreground. It’s pretty surreal.

This is a fascinating insight; I would love to see these columns of continental crust. Any ideas of a particular location to view them?

In the meantime, I wonder if there are any good photos of them? I wouldn't know what to search for.

I was describing the top of Wildrose peak there -- one of the coolest views I've seen in my life. I want to go back and try Telescope peak, which is right next to it and a bit higher and more strenuous, sometime.

These hikes aren't nearly as hot as the valley, and probably manageable even in the summer. Much of Death Valley's heat comes from the air being more compressed the lower you go, so if you're 6000 ft up it's not that bad at all. Although, be careful.

Here's some pictures I found online: https://www.americansouthwest.net/california/death_valley/wi... . Note that the rock below you has clearly toppled over to almost a 45 degree angle. All the mountains in the distance are like that also.

A few hours later I was on a different ridge and a bunch of fighter jets flew through a canyon _below_ me. Death Valley is awesome. (although that may have been right outside of it?)

I searched "west ridge of death valley" and found this: https://live.staticflickr.com/4895/44030456180_28939e0a06_b.... . Maybe this was what gp was talking about?

Recent LA transplant here. Fight or flight did not kick in. Instead, I was mostly confused and kinda paced about the flat while the earth shook. I always imagine myself acting quick on my feet like a movie hero. Two learnings; I know what an earthquake feels like and I need to increase my disaster preparedness.

I'm from Nepal. We had a 7.8 earthquake in 2015 which was pretty devastating.

When the first quake happened, I did run. But it didn't really occur to me that we'd had an earthquake until after. It was like I was auto responding to an emergency, but the mind hadn't had time to process that it was an earthquake.

And, this is considering the fact that we'd sort of known that a big one was due soonish.

Get off HN right now and go and make your bug-out bag.

It should contain all your valuable documents, medication if you need it, first-aid kit, spare water bottles, emergency food and water for 5 days, backup cell device, etc.

Nobody living in a quake zone should be content with themselves unless they have a proper bug-out bag prepared .. you don't want to be fighting for scraps in SoCal after a big quake.

(I once watched two little old ladies - grandma's - beat the shit out of each other in a 711, fighting over the last bottle of water on the shelf..)

Any time you enter a room, look for a strong table. It'll become habit after a couple quakes. :)

After something bigger, you'll be one the lookout for unreinforced masonry, and crossing the street to avoid it. For example: http://www.stuff.co.nz/the-press/news/christchurch-earthquak...

Here some good material on unreinforced masonry:


After something bigger, where buildings collapse and stories of families where half got out and half didn't, you will always be aware of the quickest exit and where to be outside so buildings don't collapse on you

If you spend more than 3 hours a day near such a table, then place some water bottles and optionally non-perishable food close to the table.

That's what a far away earthquake feels like. A close one, even a much smaller but nearby magnitude 4 feels very different.

It's like what happens to thunder when it's far away.

Here to plug the American Red Cross emergency apps. They have high quality, offline-available info on preparation and survival of various natural disasters. I believe they also push out real time info on them about relief efforts, shelters, etc. Here is the Earthquake app: https://apps.apple.com/us/app/earthquake-american-red-cross/...

Just downloaded it. Great app. Lots of useful info. Thanks!

Maybe the timing was coincidental, but it looked like reddit was down for a few minutes after the earthquake (I checked some other sites to make sure it wasn't just my router being silly after power came back). Reminded me a bit of how almost every news website (barring Slashdot) went down on 9/11. I wonder how many sites could handle the load if a serious disaster happened. Makes me reconsider where I'll be able to get info when something bad happens

HAM Radio or SDR! It's worth picking up something as inexpensive as a Baofeng or RTL2832U transceiver, even just to listen on common frequencies.

I have one of those cheap RTL-SDR dongles that I use for listening to ADS-B messages. Other than listening to FM radio, do you know if any other good uses in a disaster situation?

FRS and MURS frequencies would probably be most ubiquitous and useful in an emergency. If you get a second SDR, you can "hop" and listen to trunked frequencies used by emergency services, local and federal channels. Or you could buy a scanner from Uniden for something a little easier. I can highly recommend the SDS-100 - https://uniden.com/products/sds100-true-i-q-x2122-digital-ha...

Find out what frequencies are used in your area for HAMs participating in disaster response.

Even better, get your ham license before you need it, and practice getting on the air with emergency nets and just to chat with fellow hams.

Any HN regular should be able to study for a few hours and pass the Technician test. This gives you access to all the VHF and UHF frequencies that are often used in emergency communications. A bit more study and you can get the General license, which lets you use more HF (potentially longer range) frequencies.

Here is a good place to start:


Many hams start with a cheap Baofeng handheld. These sell in the $25-60 range. Here's one I have and recommend - it's at the high end of that range but has several improvements over the cheaper ones including a better antenna:


Ham radio has been popping up on HN a lot lately. Besides emergency communications, there are a lot of interesting things you can do once you get your license. Feel free to holler with any questions!

> Any HN regular should be able to study for a few hours and pass the Technician test.

This isn’t hyperbole. I got my Technician license after literally only studying for an hour (admittedly I had some prior experience, but most of what the test is just memorizing various things you should know).

Second this. There are a few study apps that make use of free time on the toilet for a few weeks and you’re good to go.

I have probably a dozen RTL SDR’s strewn about boxes and junk drawers, but the idea of relying on them in an emergency is unsettling. The little baofengs have a terrible interface but last a long time on a charge and are pretty rugged.

The point about practicing is legit. Most comms with these radios happen with relays, but you’ll want to know where people will be in simplex (walkie talkie style) operation if there’s no infrastructure.

I had the exact same thought also because of 9/11. I am in British Columbia and I got a vague provincial emergency alert saying there was no tsunami threat. Amazon Prime was also failing at the same time. Facebook was loading but then the USGS site was failing.

Remember the phones after 9/11? Long distance calls were touch and go for, IIRC, days. Barely worked at all day of, might get through on like your tenth try and then probably get disconnected after a minute or two. Good thing ICQ existed.

Relatedly, remember when long distance vs. local was something you had to consider when making a call? Hahaha.

In Japan during the 3/11 earthquake, the only way people were able to stay in touch was via Twitter and other online chat apps (LINE, Viber, etc). The phone lines couldn't handle the load.

Maybe the proliferation of more 5G towers could make the internet more resistant?

usgs.gov was returning 504 within 10 minutes of the event.

I grew up in Ridgecrest during the time it became known for earthquakes (e.g. https://www.youtube.com/watch?v=8k8f2gJjXkQ&feature=share ). That commercial isn't far off in that it got to the point that we no longer ran for cover. I remember watching TV and feeling the ground roll underneath me and not being phased.

Random notes:

- The epicenters tends to be relatively close (<20 miles) and relatively shallow (<10 miles).

- I think the 7.1 brings this into the territory of stronger than we had growing up.

- I've seen people mention that it didn't impact a densely populated area. Normally I feel the same relief about that except this time I know the people which brings a different perspective

- My biggest concern is for those who were evacuated from the hospital in the 100 degree weather. A childhood friend's dad is bedridden, trying to recover, and is now out in the heat.

- I've seen reports of roads to towns like Trona being closed off. Unsure if that is all routes and how long until they re-open but that is probably my next biggest concern.

Epicenter is very far inland, approximately halfway between Bakersfield and Las Vegas. (Not Angeles) Densely populated areas are minimally affected.

I was in the 8.8 earthquake in chile (2010), near the epicenter. for the following days, a lot of replicas over 7.0 occurred. if your construction follows the regulations, it will be fine (some minor repairs), but any structural damage can and will be the death sentence for that structure. In those times, we were worried about the lack of water,food and electricity.a big freezer stuffed with food can last a week without electricity, because of the insulation and the amount of water inside

I live in a two-floor building though, and the oscillations are amplified by tall structures, so be safe

I think that depends on the dominant frequency of the earthquake.

What happened to proof reading? I do not understand how the second paragraph of a major article in the LA times could have an error like this:

"Scientists said it the fault causing the quakes appears to be growing."

In some situations it can be more important to get the news out than to have it perfect. Whether this is one of those situations I don't want to make the call on since I'm two continents and one ocean away from it but I can imagine that there is some pressure with an event like this.

We were rocking pretty good in Orange County. Can't imagine being at the epicenter. It lasted long enough to where we start questioning if we needed to do anything.

Was browsing hackernews and suddenly felt bed shaking , thought it was due to tiredness (been to beach).

First time felt earthquake .. Surreal experience

The sound is the worst part for me. Nothing else even comes close to replicating it. All the little things rattling, and the deep rumbles of your whole house moving around.

Totally. The fact that the sound just comes from everywhere makes you realize how puny you are. The massive rock you've lived on forever, and get by day to day without thinking about in detail, is all of a sudden very, very real.

Yea, the first time I felt a decent sized quake I realized, oh, it’s not a localized shaking — the whole damn earth is moving.

I grew up in a canyon with a fault that splinters off the San Andreas Fault. You could hear the Earthquake right as it approached and as it rolled away. Always wild. A p wave could wake you, you would hear a rumble, start to shake, and hear it leave.

I had my first earthquake a few years a go and it is for sure a weird feeling. I’ve never felt an entire building move until that, it’s a unique feeling

My first experience of earthquake was when I was on vacation on Big Island. The wall rattled like someone is keeping hitting it with full force. Then things on table shaking. I tried to phone the frontdesk of the hotel I'm staying to check it, and the line was busy for at least 10 minutes. Guess everybody is wondering what's going on.

I'd been awake for over 24 hours when I felt my first earthquake. I also wrote it off as exhaustion.

The Northridge quake and its aftershocks screwed with my sleep patterns for weeks. Every single time an aftershock fired up, it was a no-sleep night that day.

Its very important to work on ones mindfulness during quakes.

happened to me in Delhi. My couch started shaking on its own. Thought my sibling was playing. Turned out to be an earthquake.

This article sure went up quick!

"This article documents a current earthquake. Information regarding this event may change rapidly and may be unreliable."

I'm flying to LA next week for the first time, and am a little worried after the quakes. I appreciate much of the comments on preparedness and observing what's happening around you, but am looking for some more details, like:

- how to spot "unreinforced masonry" in order to avoid it?

- why is a strong table to be looked for inside, to get underneath it?

- I would imagine basements are bad to be in, is that so?

- I would imagine upstairs is a bad place to be too, right?

- does the ground really split underneath your feet?

Honestly, I wouldn't worry too much. These earthquakes are far enough away that LA shouldn't be feeling too much and they should calm down soon. The likelihood of other earthquakes cropping up seems relatively low.

> why is a strong table to be looked for inside, to get underneath it?

Modern buildings don't usually completely collapse ("pancake"), and being under a sturdy table can absorb the weight of partial collapse: as an example, an interior wall collapsing onto you. See [0].

> I would imagine basements are bad to be in, is that so?

All I know about this is that having a (code-compliant) basement makes the entire house more resilient, but I couldn't find anything about being _in_ the basement during an EQ being good or bad. Know that basements in low-density structures are quite scarce[1] in Southern California, though -- I've lived in LA for four years and don't remember ever being in one, except in large apartment buildings.

Don't try to get out of a basement if you're in one when an EQ hits. Most injuries are a result of people breaking their ankles and legs trying to move while the ground is shaking.

> I would imagine upstairs is a bad place to be too, right?

It's a tradeoff. In the event of a structure collapse, you have further to fall but less structure to fall on top of you.

> does the ground really split underneath your feet?

Yes, if you're straddling the fault line and standing near the epicenter. (You won't be doing that).

There has never been a confirmed case of someone falling into an "earthquake chasm", but it might be something to worry about if you're a cow grazing in a Bay Area field[2].


Take a look at this study[3] of the 74 deaths caused by the '94 Northridge EQ. It's the best data we can use to project what would happen if a major EQ hit LA today.

[0]: http://www.cnn.com/2013/07/04/tech/innovation/the-earthquake...

[1]: https://www.latimes.com/home/la-hm-basement-side-20150509-st...

[2]: https://www.realclearscience.com/blog/2013/01/do-people-ever...

[3]: http://www.iitk.ac.in/nicee/wcee/article/11_979.PDF

Who else in the bay area will finally get its earthquake-readiness kit tomorrow morning? :)

I’ve been thinking of getting us one of those for the past 15 years!

Maybe tomorrow will be the day...

Good thing burning man is so soon, half of silicon valley is probably already well stocked and prepared.

Would be cool if Siri had a better answer to "what do I do during an earthquake?"

If my time in Japan has taught me anything, it’s to get under something. The big danger is stuff nearby toppling onto you and immobilizing you. Bookshelves, wardrobes, floating cabinets, drop ceilings, and such can hurt you unless you pop under a table or desk quickly.

In Japan, they have earthquake simulators that drive this point home. The old version is a truck whose bed is fitted with a simulated apartment on hydraulic shakers. The newer version is VR.

Your second concern is fire. In Japan, gas is always run through a sensor that cuts the line if shaking is too intense. I’m not sure if California has the same. If there’s a gas leak nearby, that’s the next serious danger after falling objects.

Get under a strong table, away from glass.

Do NOT get in a doorway, unless it is one without a door. The door is more dangerous than any other damage.

Do NOT run outside, unless it's faster than getting under a table. And if you do go outside, get away from power lines.

* don't run during an earthquake, you'll break your leg.

* bathrooms with plumbing in the walls are supposed to be a little stronger.

* blankets can help protect you from breaking windows.

* if you are outside, watch out for trees, powerlines, things falling off buildings (tile roofs, pots), esp. brick buildings

Break your leg? I find that one hard to believe.

The ground literally rolls up and down like a wave. You can see it move if you stand still in an open field.

It’s definitely not something you want to run on.

have you ever been in an earthquake? esp. outside? it's like trying to run on the swells of an ocean.

Here are results on the web for what do I do during an earthquake.

Yeah, I looked at them, but I would imagine that saving ~15 seconds in getting the info to people could prove really valuable at a large scale.

That was a comment on the uselessness of Siri, except for voice recognition of a web search query I guess.

what is its current answer?

Standard web results. I guess I would have preferred some kind of quick tts summary from ready.gov or something.

Google Assistant on android gives a summary. It seems incomplete but it has a small summary thumbnail and the first two items. It's from Victoria State Emergency Service in Australia for whatever reason.

I've found Google's AI to be significantly better than Siri.

Would be nice if Siri told me an earthquake is coming within seconds

As someone living on the second floor of a rather old (built in 1940s) apartment building in Northern California, I’d love to hear any suggestions for ensuring it’s safe in the event of an earthquake like this.

Why is there no mention of China Lake here? If the quake was NE of Ridgecrest, does that put it on the rather extensive China Lake weapons facility?

There was one paragraph:

> The quake caused further damage to a U.S. weapons testing facility outside Ridgecrest, the Naval Air Weapons Station China Lake, although details were sparse early Saturday. “NAWS China Lake is not mission capable until further notice; however, security protocols remain in effect,” the naval base said on its Facebook page after the latest temblor. The installation is the Navy’s largest single landholding, sprawling over 1.1 million acres, an area larger than Rhode Island.

Presumably the federal government is taking care of China Lake and doesn't want anyone to know about it. I don't see why they would invite the press onto a classified weapons research facility just to catalog earthquake damage. When you're a wealthy landowner housing thousands of explosive munitions in an active fault zone, presumably you build it to withstand earthquakes.

But yes, AFAICT from the maps, the epicenter was basically right under China Lake.

>When you're a wealthy landowner housing thousands of explosive munitions in an active fault zone, presumably you build it to withstand earthquakes.

The Naval Air Weapons Station China Lake in Ridgecrest was evacuated and deemed not "mission capable" https://ktla.com/2019/07/06/naval-air-weapons-station-china-...

I'm not saying this is related but I suddenly thought about the internet problems lately.

Animals sometimes can feel earthquakes coming. Little is known about this but it is suggested that it has to do with electromagnetic fields.

We experience problems on earth when there were bug sun flames.

Could a big earthquake influence our communications?

The earthquake even cause the Mars Reconnaissance Orbiter to lose its signal lock.


This shook my hotel in Vegas. We evacuated but it was pretty minor. I'm glad to be leaving tomorrow!

The windows and doors were creaking and making loud cracking noises. Both times it felt like an unbalanced washing machine on a different floor.

I’m sure it must have been rough for people near the epicenter and I hope everyone is okay.

Here in Los Angeles we felt it for sure but a quick survey of friends around town indicates that there wasn’t much damage.

Thankfully everyone is reporting in safe from what I've seen on facebook (I grew up in the area). As mentioned elsewhere, my biggest concern is those evacuated from the hospital into 100 degree weather.

We had some very minor shaking in Tijuana.

Thankfully the epicenter appears to not be in a densely populated area. Hopefully those in Ridgecrest are all ok.

I feel bad for all the stores that just finished putting everything back up on shelves. There were libraries looking for volunteers to help pick up fallen books.

That said, it does look like there was some damage from this one. The news is showing videos of burning buildings

Bit off topic, but it's amazing when you're in another time zone how hard it is in 2019 to actually workout when an event occurred, there are dates everywhere attached to this event, some with the timezone listed, some without. When you do have the time zone, conversion isn't trivial.

I hope someday at least the Internet works on UTC :)

Felt it here in Vegas. I can’t believe that was all the way in Southern California!

It wasn't really. It's at the south end of the Owens Valley, about as close to Vegas as LA.

Downgraded to a 6.9

Must still be working on estimate. Back to 7.1

And back to 6.9!

The email from USGS said 4.8, I was surprised it was so far off. They still have not sent a revision. Usually they are much better about this.

That may have been for another, smaller quake (one of the larger aftershocks of yesterday's 6.4 event). It looks like there was a 4.6 aftershock which may have triggered the email (the email system is automated).


I prefer the caltech site for fast no-nonsense page loads: Map: http://scedc.caltech.edu/recent/ List: http://scedc.caltech.edu/recent/Quakes/quakes0.html

back to 7.1

They must have just pushed a security patch.

Very worried. Good time to start reprioritizing things in my life.

After checking the build quality of the places around here (SFO bay area) I'm getting concerned too.

Make sure to have a backpack with some essential items there. Have some gallons of water and make sure to have a plan in the eventuality of an accident, for example, make sure to close the gas main valve. Sync with your family on where to gather if they are at work/school, etc.

I was there for the 9.1 @ Chile in 2010 and all of this was super helpful, within 10 minutes my whole family was gathered in our parents house and we were already saving water in our bathtub and pans (which was super handy, because we had no water for about 3 weeks)

How ere you able to save water? Was there water pressure for a short period of time?

I always imagine water pressure being lost right away, so if you didn’t have water already stored you’d be SOL

Not OP, but the distribution system of water is almost entirely fed by gravity from a water tower. Losing water pressure usually means loss of the power to the pumps supplying the water towers, not breaks in the pipelines themselves. There's enough water stored in the water towers to satisfy usually a few hours of demand, and the water in the pipes might satisfy a few hours more if you live at a low enough elevation.

One of the issues in an earthquake is potential damage to the major distribution pipes. From “source” to “buffer” (local reservoirs used to maintain pressure) and the extent to which things in the network of pipes can be rerouted depends a lot on how it was built. In heavily built up areas there’s often “secondary buffers” like storage on the roofs of buildings in New York City.

Pressure in the “customer end” of the water supply network will still be available for a little while (minutes to hours) in the event of damage but damage will take time to repair and the impact of the damages ongoing effect and the time to repair make one of the most basic survival tips for the average person not otherwise maintaining survival supplies: “fill the bathtub and anything else you’ve got”. You might have 15 minutes before the broken pipe washes away enough dirt that pressure drops enough to stop the flow from your tap.

It was not lost right away, it was working for several hours, around 12, but with a very low pressure. Since this happened on February (summer time) we were lucky one of our neighbors had a pool full of water we used for the toilet :)

> After checking the build quality of the places around here (SFO bay area) I'm getting concerned too.

Infrastructure or buildings? Wood-frame buildings without a soft story are pretty safe, at least in terms of not killing you.

Buildings mostly, I guess they will move harmonically with the ripples as wood is pretty flexible but I still freak out thinking they could fall over my head lol

Check this out: https://resiliencymaps.org/

Some googling tells me Florida and North Dakota are the safest states in the US.

Outside US it's Antarctica, but it sounds rather inconvenient..

Florida has hurricanes though.

Not to mention the risk of "Florida man".

There's a reason for all those Florida man stories! Might change your mind about them: https://www.miaminewtimes.com/news/how-floridas-proud-open-g...

Or the sunny day floods and the eventual submersion.

Also alligators!

Also sinkholes and flooding caused by global warming!

In Florida you are a dice roll away from getting your house leveled every decade.

I would think Arizona is safer than Florida. A lot of DR datacenters in Phoenix.

Arizona ranks very low on frequency of natural disasters, but there is a lot of temperature related aggression. Its kind of normal to be threatened with a gun.

That is absurd. I’ve lived in Arizona for almost 15 years and I don’t think I know of a single person who has ever been threatened with a gun.

Over 40 years in AZ and same experience.

What's the source of that information?

Personal experience. Here is a study to back up the relationship between heat and aggression:


If true, this doesn't bode well for the recent heat wave in Alaska, which is already the most violent and dangerous state in the US.

I'm in North Dakota right now for a few days from SF... you'd be trading earthquakes for mosquitos, ticks, and snow!

A startup @yourjumpstart for earthquake insurance pays out even if you have no damage, assuming you are in the epicenter of a large enough earthquake.

Considering the trouble that more established insurance companies have with large natural disasters, I would be a bit wary of a startup for something catatostrophic like earthquakes

I just looked into it. Their max payout appears to be $10,000. That's not a lot. It's not to rebuild your house or anything, it's just to pay for a hotel for a while and maybe some new food.

I always considered earthquake insurance a waste of money. The premiums are high and deductibles are quite high so a quake would have to be very strong to do enough damage that cost of repair was more than the deductible. And if that was the case then there would be widespread damage and a huge amount in claims. Seems unlikely even a big insurance company could remain solvent and pay out.

Insurance companies are insured against big payouts (reinsurance). As long as it’s not the literal apocalypse, they will pay.

LA getting "the big one" would be a hell of a local apocalypse, at least.

In "A Tale of 5 Crashes" the gold requirements from fire insurance in San Francisco in 1906 caused the increasing of rates in England

Agreed. There is no way that a startup is capitalized enough to survive a payout. Their CEO and investors must be sweating bullets over the next few days, worrying if an earthquake hits closer to LA

I'm sure they're just reselling a real insurer's product with some marketing and a web 2.0 website. No way an undercapitalized startup is allowed to actually underwrite their own insurance contracts.

yeah, according to their FAQ:

> Jumpstart is a surplus lines insurance broker working in full compliance with applicable insurance regulations. The insurance described here is effected with certain Underwriters at Lloyd's, London.

Let me guess, that startup is in southern California.

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