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Episode 60: Earthquake Machine, Exploding Lava Lamp

  • Earthquake Machine: Nicola Tesla invented a device capable of generating earthquakes. busted
  • Exploding Lava Lamp (and other household items on stove): a lava lamp on a stove can explode with lethal force. confirmed. Other household items tested include:
    • can of beans: small cans probably not lethal but larger cans could be
    • canned meat (spam): probably non-lethal
    • glass jar of milk: possibly lethal if you were looking directly down on it.
    • "Big Bertha" lava lamp: the lamp broke into small spears of glass and shot around. confirmed lethal

Watching slo-mo video of lava lamps exploding was more fun than watching actual lava lamps, but I'm not sure where the MythBusters even found a glass jar of milk. I found the small explosions to be more interesting than the Tesla earthquake myth, given that there was no real way in which the MythBusters were going to replicate the myth this time around. They were surprised at their ability to get the old Carquinez bridge to vibrate, but nothing was violently shaken apart.

Tesla's Earthquake Machine

Myth: Nicola Tesla invented a working earthquake machine

Tesla claimed multiple devices of mass destruction, including a death ray that could destroy 10,000 airplanes and the ability to split the Earth in two with some well-timed explosions. The MythBusters focused on Tesla's own recounting of an earthquake machine that he built.

"I was experimenting with vibrations. I had one of my machines going and I wanted to see if I could get it tune with the vibration of the building. I put it up notch after notch. Suddenly, all the heavy machinery in the place was flying around. I grabbed a hammer and broke the machine. Outside in the street there was pandemonium. The police and ambulance arrived. We told the police it must have been an earthquake. I told my assistants to say nothing."

Tesla also described testing his machine on a 2 foot steel bar:

"For a long time nothing happened. But at last the great steel link became to tremble and finally broke. Crowbars could not have done it, but a fusilade of taps, none of which would have harmed baby, did it."

Searching the patent office, they were able to come up with Tesla's design for the earthquake machine: the Tesla Oscillator. The design was a mechanical oscillator generator featuring a central rod, motor, and air cushion. The speed of the vibration of the rod could be manipulated and Tesla claimed with proper tuning, it could destroy anything.

The destructive powers of mechanical resonance are well-known, with perhaps one of the most famous events being the Tacoma Narrows Bridge collapse. In their very first season, the MythBusters tested this idea with marching soldiers aka "Breakstep Bridge", which was shown to be plausible under revisiting (revisiting was cut from actual episode).

Prototype 1

They built their first prototype using a jackhammer, which has the mechanical oscillation requirement of Tesla's machine. They replaced the chisel with a rod, added an air cushion, and made the frequency tunable -- viola, Tesla Oscillator. But it didn't run very well. Jamie and Adam argued over the design, focusing in on the air spring, which was causing it to oscillate very slowly -- 2-3 hertz. Adam wanted the air spring to stay exact to Tesla's device, but Jamie wasn't happy with the ineffiencies that the air cushion was creating.

Prototype 2: Mechanical springs

Adam and Jamie came up with a compromise that was compatible with Tesla's requirements: Jamie replaced the air cushion with mechanical springs. Tesla had preferred air cushions over mechanical springs because they have no inclination to break. They tested their prototype on a 2 foot bar to replicate Tesla's initial test. The MythBusters had a bit of trouble replicating Tesla's test -- amusingly enough, the mechanical springs that Tesla noted had an inclination to break, broke.

Wave tank

With two failed prototypes, they decided to go back to the drawing board with some visualization tests. They setup a water tank with a bulb bouncing up and down in it. Minute variations in the frequency of the bulb -- 1.5 to 1.6 -- caused major variations in the waves in the tank. With the principles of mechanical resonance visualized in their heads, they went back to prototyping.

Prototype 3: air-powered autotool

They next tried an air-powered autotool that was already so close to Tesla's design that all they had to do was mount a plate on it -- so that it could be attached to the target object. They tried running the test on the 2 foot steel bar again, but they couldn't tune the device and the bar: the frequency of the device was about 52 hertz; the lowest natural frequency of the bar was in the hundreds. They next tried a 2' foot bar of 2" square tubing -- they got a bit more shaking, but not enough. Then they went to a 20' bar, which had a natural frequency of 7 hertz. Still no destructive vibrations.

Prototype 4: Grant's electromagnetic linear motor

Grant already had an electromagnetic linear motor in his possession for an outside consulting gig. The motor was frictionless, like Tesla described, and it was also tunable in .01 hertz increments. All they had to do was clamp the motor to the side of the steel bar. The 20 foot bar started bouncing up and down with a steady beat -- the deflection from the 5lb device was much more than Adam standing on it could create.

1/6 scale test

They built a 1/6 scale of Tesla's building and a 1/6 scale oscillator out of a microcassette recorder. Nothing happened. Breaking with their scale, they attached Grant's device to the mock building, which didn't produce destructive forces either. At this point, the MythBusters were about ready to call it busted, but Adam wanted to attach Grant's motor to a large structure -- like a bridge -- to see what would happen.

Bridge Test

They went out to the old span (circa 1927) of the Carquinez bridge (Wikipedia article) that links Vallejo, CA, to Crockett. The old span is a steel cantilever design and was the first major bridge in the San Francisco Bay Area.

Grant's motor was clamped to one of the bridge supports and they began the process of tuning in the motor. Adam and Jamie stood on the bridge as they were doing this, showing their confidence in this being busted. Adam: "MythBusters is nothing if not a compendium of ways in which Jamie and I have been wrong."

To their surprise, they were able to get the entire bridge to start oscillating. Adam could feel the vibrations hundreds of feet and several supports away. Jamie compared the vibrations he was feeling to a big semitrailer truck cruising by. Jamie: "It actually makes a little concerned, believe it or not."

After an hour of testing, though, they weren't able to get anything stronger than the vibrations they initially felt. No earthquake.


Exploding Lava Lamp

Myth: In 2004, a Washington state resident was killed by a lava lamp left on a stove -- it exploded and pierced his heart with a shard of glass.

Kari went to The Bone Room to check obtain a human rib cage and cast a ballistics gel mold around it. She also suspended a balloon heart inside so they could easily tell if it was pierced.

Grant investigated the contents of lava lamps and found many potentially flammable contents: mineral oils, wax, and alcohol.


  • lava lamp bottle
  • portable stove
  • ballistics gel chest positioned close to the stove

Test 1: safety-cap-style lava lamp

The stuck the lava lamp bottle on the stove. After a bit of heating, the safety cap of the lamp blew off, hot lava lamp contents geysered out of the top, and with no liquid left in the bottle, it quickly shattered on top of the stove.

Test 2: bottle-cap-style lava lamp

They next test a bottle-cap style lava lamp. There was a small leak out of the top of the lamp at the pressure built up, which lead to flames leaping over the bottle. The bottle exploded everywhere and left some pieces of glass on the ballistics gel chest -- no wounds, but definitely potential for injury.

Test 3: securely fastened bottle top

The bottle cap in the second test allowed some of the pressure to escape, so Tory epoxied the top of the next test lamp to help the pressure build up even more. It wasn't enough epoxy, though, as the bottle still leaked out of the side. They decided to help the explosion along by squirting some cold water onto the lamp.

Grant: "The theory was that the shock of the cold water would cause the glass to fracture -- BOOM!"

As Grant was speaking while shooting the cold water, the lava lamp exploded. A large shard of glass was left in the ballistics gel chest.


They didn't want to stop there, though. For fun they decided to start testing other household objects placed on stoves.

  • can of beans: Tory: "Not as exciting as the lava lamp, this can of beans." The top of can popped open and the contents came shooting out, mostly intact and can-shaped, and landed on the stovetop. Non-lethal.
  • big can of beans: after much waiting, they got a good-sized explosion. Tory: "I can taste beans in the air". Possibly lethal
  • canned meat (spam): very similar small can of beans: the top popped open and the contents popped out. Non-lethal
  • jar of milk: the jar exploded mostly upwards, though the bottom half did slide over to the ballistics gel chest. Possibly lethal if you were looking directly down on it.
  • big bertha lava lamp: the lamp broke into small spears of glass and shot around. Possibly lethal.


I was wondering if the machine would have done more if it had been placed somewhere different. Such as a beam that supported the base of the bridge.

What company made the "electromagnetic linear motor"?

So what are the chances that the bridge colaspe was some one trying to duplicate the Tesla experiment using more weight??

Well here is a hypothesis, resonating frequency according to Tesla, "vibrations could destroy anything" could it be possible that the horrible tragedy in Minnesota, could have been a combination of the vehicle traffic as well as the construction crews working on the bridge with jack hammers. Could somehow the frequency of the structure "bridge" was met and due to this action caused a chain reaction and basically the bridge destroyed itself, I know sounds kinda crazy but look at 2 episodes of Mythbusters to which they demonstrated that it was potentially possible. 1. Break step Bridge and 2. Earthquake machine. and read some of Nikola Tesla's publishings.

The Mythbusters should have replicated the design. There is a book that details on how to do so, called "Tesla's Earthquake Machine."

With regards to Tesla's earthquake machine, Mythbusters cannot replicate it because they cannot replicate the genius that was Tesla.

Not saying that Tesla did create an earthquake device, but I'd like to say that Adam and Jamie are far more intelligent than I am. However, as much as they know I am sure that Tesla dwarfs there scientific prowess. What the Mythbusters did was test their own creations and that's where the busted verdict came from not Tesla's device.

Yeah, I'm at the very least a year late to this topic. Probably no one will even read this, and that may not be a bad thing. Regardless, has anyone bothered to go back and study HOW Adam and Jamie LOOKED when they declared the Earthquake Machine busted when compared to things that were most definitely, without shadow of doubt, busted?

I've only recently started regularly watching Mythbusters, as it's available on demand via Netflix, but the first thing I noticed on this particular episode was that they both appear to have lied. In fact, Jamie, even as unshakeable as he normally seems, did a lot of shrugging and minimising of the results. This, as well as how they decided to shift from the actual topic over to pseudo-speculations about Tesla's inspiration of Mark Twain and other pointless noninformation (a common tactic used by politicians and PR persons to obscure the actual facts), has led me to my conclusion. It seems to me that they had a different opinion, perhaps plausible, but for whatever reason, (maybe a social liability clause or some other such thing in their contracts with Discovery,) they decided to halt the experiment after what wasn't even deemed a full hour before declaring the whole concept busted.

I also think it's interesting that they chose a bridge for this experiment. It seems to me that they could've done better had they stuck to the scale constructions. Bridges are designed with conflicts in frequency to avoid just such an occurrence.

Seriously, through, at first I thought it was kind'a strange how something with "unexpected" and "spooky" results would be declared busted simply because they didn't achieve a full-blown earthquake on such a large scale in what amounted to less than a full hour. But when I saw the conclusion, with their personal mannerisms and all the distracting and irrelevant details thrown in, I immediately noticed that they didn't seem to possess as firm a conviction as they do when busting a myth that was totally, undeniably obliterated.

Great episode, especially interesting to me as I had had a lava lamp explode three feet from me on a desk. Sounded like a bomb, glass shards flew by my ear, and very hot "lava" went everywhere including ruining my company's external modem and my keyboard. I'll never have one in the house again.

What makes me curious is what would happen if they had used a bigger earthquake machine? They said the 5pound machine could move a bar of steel with more force than a 150-200pound man jumping on it. It was able to create enogh vibration on a bridge where you could feel it hundreds of feet away. What would a 100pound machine do? Thats still pretty small scale (1 man could carry it) but 20times more weight.

Also bridges will handle vibrations better than buildings will.