Wall ... explodes?

During the storm a couple of nights ago, we heard an almighty thunderclap and our dogs came dashing into the house. Once the rain ebbed and we went outside, we found this scene just around the corner: a wall apparently blown to pieces, with cinderblock chunks thrown as far as 40 or 50 feet. It seems too far for a plain old wall collapse. Could that have been caused by the lightning strike? If so, how? Steam pressure from the waterlogged bricks being suddenly superheated, like a tree strike?

Here's a non-panoramic shot which better shows the remains of the wall, which stood a couple of inches parallel to the the garage in the background.


  1. Assuming that wall was at a similar height to the building next to it, it would seem by simple inspection to be a simple collapse. The lot appears to be filled with many of the blocks in a very close approximation of their original configuration on the wall. The blocks further away from the collapse were no doubt thrown there by the momentum they gained as their potential energy was transferred to kinetic energy. An explosion would have forced the blocks into a wider dispersal pattern, and there would probably be more blocks at a greater distance, owing to the additional energy imparted by an explosion.

    Anyone else have any ideas?

  2. Wow, quite the destruction!  Sounds like a plausible theory that lightning struck it.  Can’t think what else would have exploded it like that.

  3. Cool, look for fulgurites. Fulgurites (from the Latin fulgur meaning thunderbolt) are natural hollow glass tubes formed in quartzose sand, silica, or soil by lightning strikes.

  4. Safety margin for falling structures is commonly between 1.5x and 2x the height of the structure. Given the height of the wall, it looks to me like it simply collapsed. Notice that most bricks are close to the base of the wall and relatively fewer are further out. The further-out ones are from the top of the wall. They had more energy, so they tumbled and rolled when they landed. Additionally, they were carried further from the base as the structure collapsed.

    If it was lightning, you would expect to see scorch marks. Were there any?

  5. I don’t know, but you are in Pittsburgh. I think one of those old useless garages either explodes or collapses every hour or so in this town. And with it goes tens of dollars worth of old rusted tools.

    1. I believe that the mound off to the left in the background is actually a motorcycle crushed by the wall. I say “motor” and “cycle” but it was in similar condition to the wall and I do not believe it had moved an inch in the 4 years I have lived in the neighborhood.

      1. Too bad, because if they had borrowed a technique used by most of their neighbors, the bike could have been completely preserved using nothing more than a blue tarp.

  6. Clearly a blockworm infestation.  Isolate and fumigate before they spread to the whole building.

  7. I would first rule out simple collapse caused by waterlogged soil or water accumulating somewhere which puts pressure on the wall.

  8. David Banner was in there, and he realized he left his car’s top down just as the storm started.

    1.  Then he flipped that mother upside down with Hulk strength.  The upholstery is fine but the paint could use some work.

  9. I am familiar with one site at which the sidewalk exploded next to a tree that suffered an obvious lightning strike.  The concrete was blown apart at a place that was directly over major roots.  The explosion broke windows in a nearby house.  The explanation that neighbors were given was  rapid vaporization of water along the path of the greatest current flow.  I guess that this an anecdatum in support of the steam explosion theory.

    1. Once on a scout hike in Philmont NM, our Ranger saw a lightning storm coming. We found shelter in a large stand of trees. Out at the edge he showed us a pine tree 6 feet in diameter split almost perfectly down the middle from top to bottom from a lightning strike a week earlier. Another tree a quarter mile away nearly as big had been rendered to matchstick sized shrapnel in the same storm.

      1. In Maine about 10 years ago or so, my wife and I decided that the coming hurricane was going to block traffic up too much, and we’d be better sheltering in place at the ancient bed and breakfast at which we were staying. And so we did.

        We left the car parked in front of a pine tree, maybe ten inches in diameter.

        We came out the next morning to find the car parked in front of a pine tree stump and a strewing of splinters and needles…

  10. Did a lightning flash coincide with the thunder, so you know it was that close?  I’d be more on the side of those guessing at water/wind collapse vs. direct lightning strike.  Though thunder itself can be loud enough to rattle things, so a nearby strike might have contributed to rocking things loose just from the sound waves.  I’m going to have to ask you to reconstruct the wall, install an ampmeter and some other instrumentation and report back to us.

  11. My theory is that you had a huge mess of Carpenter Ants. As we all know, when a Carpenter Ant is injured and can’t do much more, they charge their opponent, clench their muscles as much as they can, then explode, shooting poison everywhere. My guess is that you’re lucky there was a wall to protect from the poisons. 

    I wonder what the opponent was?

  12. Lightening strike. The top part of my neighbor’s chimney was struck by lightening once – blew brick clear across a cul de sac, and no scorch marks. Looked a lot like this. That’s my guess, and that age and moisture helped increase the collapse area. 

  13. Clearly controlled demolition as the wall collapsed in free-fall time, which is against the law of physics – I would look for traces of nano-thermite.


  14. I dig my hole; you build a wall.  I dig my hole; you build a wall.  One day that wall is gonna fall.

    1. That’s probably what Remus said right before Romulus jumped over his hole and made with the stabby stab.

  15. We would need closer pictures to look for the glassy lightning tracks.  I would check the split pieces that are thrown the furthest.  I have seen this in the past when people had water leaks in the top cap which give the lightning a path to ground.  Amazing to see.  Our metal mailbox and metal post was once hit by lightning and popped out of the concrete it was set in…  We happened to watch it happen.  

  16. The city usually investigates incidents like that whether through the Fire Department (which isn’t just for fires) or one of the city inspectors.  Has anyone official looked at this?

    1.  Are you saying Rob Beschizza isn’t official?  Because you can just take that attitude of yours and leave, mister.

  17. That rusted motorcycle? It was the anchor for a spatial rift. Nothing can move an anchor unless the rift detaches, and rifts tend to detach in the most spectacular way. At least you don’t have to deal with the Things that come out of the rift any more.

  18. Could it be a difference of pressure caused by the storm ? 

    You know, Storm brings high pressure around the building.
    Pressure equalizes in the building.  
    Storm leaves abruply.
    Building  finds itself suddenly filled with a lot of air that  want to go out.
    Uh-oh moment

    I know this can happen in avalanche clouds, but the pressure then is immense. 

  19. I agree that it is simple collapse.  There is no mortar fill in any of the voids in the blocks and no rebar.  This is the kind of thing that kills people in tornado and hurricane country.   

  20. I was going to ask if they were Chinese bricks (they have problems with exploding walls), but it looks like a simple collapse to me. Probably about ready to fall over and the thunderclap rattled the whole thing.

  21. Sometimes, if there are already a few cracks in the wall, you can do this with a small bomb. You can usually pick up a few rupees and for some reason nobody ever seems to mind.

  22. Could be a silverfish infestation. Punch one of the blocks until it breaks. Be careful not to be standing near lava when you do this, cause the little buggers will push you in.  

  23. Oh, I recognize this.  

    This is where someone momentarily crash-landed during that brawl-in-the-sky/
    “thunderstorm.”  You know.  
    I don’t see any, um, pieces left, so this probably wasn’t the bad guy. And I don’t see scorch marks, so probably not Iron Man, either.  So, I’d have to go with… Superman.  

  24. Like rtresco, same thing happened to my neighbor’s chimney the week after I moved in here.  Lightning strike blasted brick 50 feet in all directions, no scorching to speak of.  Theory was it hit the wet flashing (and whatever that grounded to)…

  25. I fix stuff like this for a living, much directly though insurance companies.  I’d easily say lightning. The spread of damage is much further than a simple collapse. It’s an insurable incident. If this is your property call an agent and have them send an adjuster to look at it. They’ll probably agree. All that jazz about looking for lightening glass is mostly Hollywood rumor and “I read it on the internet” wishing. It doesn’t happen much on strikes that cause residential damage as a lot of the energy in the strike is going into causing the resulting damage..

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