Weird loud booms in northern California

Mysterious booms are rattling citizens of El Dorado County, California. Quarry owners require government permission to use explosives. The local Naval Air Station denies any supersonic flights over the area. Some have suggested that perhaps wineries are employing propane canons to scare away birds. From CBS Sacramento:

According to USGS, there aren’t enough seismic stations to pinpoint the exact location. Meanwhile, some say the booms have been around so long and happen so often they barely notice them anymore. Still, others want to solve the mystery.

“I would like to know what it is, yeah. And I’d like to know when it’s going to stop too,” said (Pleasant Valley resident Peter) O’Grady.

"Source Of Loud Boom In Foothills A Mystery" (via The Anomalist)


  1. Mysterious loud sounds seem to be the big Fortean meme these days.  I’m not complaining, but christ, last century they had UFOs – and all we get are MBSs (mysterious bloody sounds).  I blame the Inception trailer.

  2. I live in Tuolumne County which is right next to that county, and we too are experiencing loud booms, around 9-10 at night, and it was determined to be a number of Dry Ice Bomb’s – Though I am not entirely sure I believe that.

    1. That must be in one hell of a container.  I mean I’ve done similar things with 2L soda bottles before, but I doubt it would register as a “big” boom over a mile away (especially if there are trees or the land isn’t completely flat).

      1. Yeah, I live in a really small town, called Twain Harte, there are about 2500 people in my town (and that is stretching it), and it’s full of tree’s, hill’s, etc. We’re in the heart of the foothills, so to hear that loud of a boom, multiple nights in a row. It sounded like a gunshot but it echoed for far too long. 

        But as a kid when I would come up here to visit, I can remember laying in the forest looking up at the stars and seeing stealth jet’s pass me, and you heard them LONG before you saw them, flying low under the radar, with absolutely no lights, painted black. 

        Strange lights, etc are the norm here, so I really don’t believe the Dry Ice thing.. However I am not really a conspiracy theorist so this revelation surprises me.

        Edit // Apparently I am not the only one :

  3. Yep, I’m right on the border of Sacramento & El Dorado County and heard those booms a couple of times the other morning when I was out in the backyard feeding the cat. I thought it was a sonic boom. Who knows, Chuck Yeager lives around here, so maybe he was up to something ;). 

  4. I was living in Tokyo late last year when this “Boom” phenomena was going viral. Night after night the distance rumbled, boomed and vibrated like a jet tearing the sky except continuing for periods of minutes and even hours on one night. Japanese people are amazingly incurious sometimes and everyone I asked about it just shrugged and said “Dunno..” It went on for about a week and then just stopped. If I hadn’t heard it myself I would’ve dumped this phenomena into the Crop Circle bin.

    1. Whatever it is, its been around for ages.  I recently watched an interview with John Keel from the early eighties, where Keel talks about what he calls “sky quakes” – basically describing almost word for word what you describe there.  So whatever is – mundane atmospheric phenomenon, or Illuminati joy-riders thrilling across unknown velocities and skyways – it’s not new.

        1.  Well, its likely something relatively mundane, that people have become more aware of recently, owing to an explosion in social media and the generally jittery and apocalyptic mood of the times.  At any rate, I hope it isn’t Yahwah giving a few premonitory blasts on his trumpet.

        2.  You know, that’s really interesting. I have no idea what these booms are, and it’s been like a puzzle work for me to ponder what they might be. Not once had I considered water. Thanks for mentioning it.

  5. My guess: Its either something mundane… or its the Aurora bouncing in and out of the atmosphere after overflying russia/china (which since it has been going on for more than 20 years is kind of mundane now too).

  6. Residents in the town of McAdam, New Brunswick, Canada were also reporting loud booms earlier this year. I’m not sure if the cause was ever resolved but last I heard it was an earthquake swarm.

  7. I have the strangest feeling that somehow the Mythbusters have something to do with it, has anyone checked to see if they’re filming in the area? 
    Jamie: “Today we’re seeing if you can make an omelette without breaking any eggs”
    Adam: “What’s the big box of explosives for?”
    Jamie: “Ratings”

  8. It’s interesting that there were a large number of earthquakes in southern California at roughly the same time…

    I have to agree with Michael M.- it would probably be a good idea to see where the Mythbusters are filming though.

  9. would it be hard to get a number of people together in the area (3+), have them set up microphones outside, synchronize the recordings by playing a bit of a radio station out loud at a preset time, and share the results after a couple of booms have been heard? triangulate based on gps coordinates and the delay until the boom is heard at each mic. source found.

  10. Take a GPS receiver, with one pulse-per-second output. Take a microphone. Connect the microphone to one (e.g. left) and the GPS-PPS to the other channel of a sound card input. Record via e.g. Audacity. Do it simultaneously at several places. With today’s size of hard drives the recording can go for many hours to couple days.

    A single-second accuracy can be achieved by syncing the computer clock via e.g. NTP (or even with the GPS receiver on a serial port). A submicrosecond accuracy then can be derived from the edge of the PPS signal and counting samples from it.

    Compare the precise time-of-arrival of the signal at several places with known position (again, the GPS will do a good job here).  Use the meteorological values for air pressure/temperature/humidity to get reasonably accurate speed of sound. Calculate the position of the source.

    1. I would second this idea but add that I would treat this as a triangulation problem using spherical geometry rather than planar circular geometry which will tend to either prove or disprove an airborne  source of the booms.  Either that or if you try to solve the triangulation in a planar and find that none of the circles touch, then you know that the source was elevated.

      Ugh, nevermind. you would have to know exactly when the event started, I guess visually or something, in order to calculate this!

      1. That’s what I meant! This is the same time-of-arrival method used by passive radars, e.g. this:

    No. Nothing to do with underground frack mining at all. None whatsoever, na ah. No siree-bob! Oh no, no, no, no, no.
    Makes too much money to be a problem for anybody, even if they can set fire to their tap water!

    1. Well I don’t know about in California, but here in NC we haven’t started doing fracking yet.  And from everything I’ve seen it’d be highly unlikely we’d do it on the coastal areas of the state anyway. 

      Besides realistically this seems like an atmospheric phenomenon.

      1. Atmospheric? Causes by what, several times a week? It just seems man made to me and nothing to do with weather.

  12. My parents live in Pleasant Valley, and they hear the booms every weekday between 11am and 3pm. I’ve never heard them, as my visits are usually on weekends. But… I do recall hearing sonic booms in the summers when I’d visit my grandparents up there. I’d see the jet go by sometimes (not always). That was in the mid 1970s, though. Here’s another story from the local Placerville paper:

  13. “The local Naval Air Station denies any supersonic flights over the area. ” Well, that’s that then. C’mon! If there’s a Naval airbase in the area that’s it, 100%. Practically the whole southern east coast from Virginia Beach to Parris Island is military – sonic booms go off all the time and EVERY time the local base says, “Weird. Not us though.” When pressed by local media they always say their pilots know better and are under orders. Doesn’t mean anything.

Comments are closed.