M4.6 Earthquake – 2 km ESE of Berkeley, CA
45 comments
·September 22, 2025smcleod
vallismortis
It was centered half a mile from Berkeley Lab at 2:56am, on the Hayward Fault. Knocked out the elevators in my building and one other building, but other than that no obvious issues. We've been told to be on alert for anything that looks off. Hard to predict how this affects some of the Lab equipment.
FWIW, I've been expecting something like this. The Pacific Rim ("ring of fire" or whatever you want to call it) has been overly active, and that second 7+ magnitude earthquake in Kamchatka was definitely not a coincidence. That said, earthquakes are not my area, but it is a topic we talk about in terms of catastrophic failure of storage systems as "Hayward Fault Tolerance" where we have tertiary backups in a region outside of the earthquake zone.
sbuttgereit
And that was just the automated response... it was downgraded to 4.3 an hour after the event.
4.3 will certainly get your attention if you're relatively close-by... but yeah, worth a "did you feel that?!" on the local news and not much more.
numpad0
Magnitude scales and felt shocks don't really correlate well. These are like Wh and V, only roughly indicative of each others. You have to look into maximum recorded accelerations.
bombcar
Everyone is secretly (or openly) waiting for Teh Big One we’ve been promised for decades, when Western California will fall into the ocean and Las Vegas become a seaport.
Taniwha
There's an SF short story (Larry Niven I think) about a seismologist who predicts the big one, but the math is not quite right, the story gets out, panic ensues everyone heads for Nevada, he guy is still working in his lab trying to figure why the sign on his equation is coming out negative when all the rest of the US falls into the sea leaving just his part of CA
cheschire
“… Alaska can come too.”
BoorishBears
I was awake and it was definitely stonger than any I've experienced in my 3 years in SF
I'm pretty sure this is the closest epicenter to SF I've seen too (at least one that was noticeable)
brian-armstrong
Many of us on this website live in the bay area. The earthquake woke us up with a stern jolt and now you're witnessing a shared moment in the community as we try to drift back to sleep.
SequoiaHope
I was in a hot tub with friends! We wall went to Portola Music Festival and we were having a nice connective low key evening when this big shake surprised us!
wateralien
I was in a self-driving cab while live-tweeting an founder therapy circle on my way to my rooftop co-living space for a seed round pitch for my biohacking startup!
jl6
Peak California, right here sir.
haunter
/r/bayarea thread already has hundreds of comments
https://old.reddit.com/r/bayarea/comments/1nnia94/earthquake...
sedatk
This was the strongest earthquake I felt since I moved to Bay Area ten years ago. Luckily, it was quite short. Woke me and all my friends in the SF and vicinity up though.
huevosabio
Same. Been 12 years in SF and this was the strongest. We were awake as well so we felt the whole thing. I think I saw the walls move.
Luckily it was short.
rbanffy
Contrast that with my experience in Ireland - 10 years and I heard thunder only twice, and saw a lightning strike only once. We sometimes get alerts due to some tropical storm that made its way up here, and the most we need to do is to collect our garbage bins and avoid biking because of the gusts.
marcosscriven
I’d say the same about East Anglia in UK, but in early ‘90s there was a tremor strong enough to notice. It was particularly strange then because you had to wait for the news on TV or radio to mention it.
idiotsecant
There's no thunder in Ireland? Why?
subharmonicon
Second strongest I remember in my 16 years here, with the 2014 Napa Quake being notably more shaking.
ghaff
I was in SF on a trip at the time and I got woken only by a few friends texting me to check that I was OK.
SllX
I usually don’t wake up to these but this one jolted me awake. I wish I had slept through this one though.
sidcool
Seems like a minor earthquake. Does it deserve top of HN?
rbanffy
I would assume someone new to CA would find it concerning.
It's fun to think about it - some Japanese people would move to CA just because of the more stable geology.
roenxi
> The U.S. Geological Survey's most recent forecast, known as UCERF3 (Uniform California Earthquake Rupture Forecast 3), released in November 2013, estimated that an earthquake of magnitude 6.7 M or greater (i.e. equal to or greater than the 1994 Northridge earthquake) occurs about once every 6.7 years statewide. The same report also estimated there is a 7% probability that an earthquake of magnitude 8.0 or greater will occur in the next 30 years somewhere along the San Andreas Fault.
~ https://en.wikipedia.org/wiki/San_Andreas_Fault#The_next_%22...
I question their research skills. I would avoid California if geology was my main motivator.
kijin
There is an 80% probability that an earthquake of magnitude 8-9 will occur in the Nankai trough (massive subduction zone along the Pacific coast of Japan) in the next 30 years. Yes, you read that correctly. Eighty percent. It's almost a certainty.
San Andreas sounds like nothing by comparison, especially since it doesn't pose as much of a tsunami risk.
bamboozled
Why would Japanese people move to CA for the more stable geology ?
notmyjob
Because there are no longer any other good reasons to move here.
ChrisMarshallNY
Japan is one of the most seismically-active areas in the world.
As a result, [modern] Japanese construction is incredibly resilient.
I've never been in Tokyo, during a strong quake, but I'm told the skyscrapers wave around like drunken dancers.
0manrho
It's a point of comparison to illustrate the differences. CA is seismically active, but not to the degree of Japan. Reading any further into it than that was clearly not the intent and would be foolish.
0manrho
It is a minor earthquake, especially for a region with generally high standards and tolerances for actual earthquakes. It's enough to certainly notice (if you're awake) and make people look at each other like "Whoa, neat" but that should be the start and end of it.
ChipopLeMoral
The votes seem to suggest it
AlecSchueler
It's notable for people in California where a lot of HN users are based.
sethammons
The point is it is not notable. It is business as usual. These happen multiple times a year. It is nearly as notable as a rainy day in LA in the summer.
AlecSchueler
I must have been confused by all of the people in this thread publicly noting it and explaining how they perceived it.
TinkersW
No it isn't, I grew up in NorCal with earthquakes, a 4.6 is a complete nothing burger, you shrug and continue about your day.
BoredPositron
It's gone sooner if you don't interact with the thread...
tgsovlerkhgsel
Isn't this the opposite of how it works? My understanding there is some algorithm that severely downranks threads that get a lot of comments in relation to the upvote count.
perching_aix
Is HN's content recommendation algorithm public?
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t0lo
My prayers to dismantle the AI industry have been answered
4.6 is really small, what's the actual news here? Was it strangely shallow or something?