Earthquake detector could have helped during quakepocalypse

[Andrea] built a seismic wave detector that warns of a possible impending earthquake. Because P waves travel much faster than the “make everything shake” S waves, building a device that detects P waves serves as an early warning system that alerts building occupants to go under a door frame. [Andrea]‘s build detects these fast-moving P waves and only took an hour to make.

Last August, those of us on the east coast of the US had to live through Quakepocalypse, a magnitude 5.9 earthquake centered around Middle of Nowhere, Virginia. For those of us who have decided to stay, rebuild, and put our garden chairs upright again (so brave…), [Andrea]‘s build could have been very useful.

The mechanics of the build is very simple: a pair of springs and levers are electrically wired together so that whenever there’s a sudden shock, a buzzer goes off. It’s very similar to an ancient Chinese earthquake detector that detects P waves by dropping a ball into a frog’s mouth.

While we’re not sure if a few of [Andrea]‘s devices would be needed to detect P waves coming in off-axis, the build is simple enough to build dozens of them. Check out the video of the build in action after the break here.

 

Comments

  1. chris says:

    this video is private?

  2. David S says:

    Also, while P waves travel at nearly twice the speed of shear waves, how much time does that really buy you for big shaking considering that energy also follows an inverse-square relationship so the further away you are, the more likely you don’t need to run and hide (although the type of ground you’re sitting on will also have a strong impact on the shaking).

  3. rand says:

    Appears to be….

  4. Baz says:
  5. Mike Field says:

    5.9? Ha! Last year I had the joy of a 7.1 10km away. Did I pick the wrong night to leave the water in the sink… The P-wave woke me, just longer enough to say “What the F@#k?” and the S-waves trashed everything.

    In any sizeable aftershock you feel the P-wave before the S-wave, but as they are all local you only get a seconds notice – just long enough to turn to each other and say “Earthquake????”, and then play “guess the magnitude”.

    Even that gets tiresome after a while. Check the link if you want to see a mashup of the 7,640 quakes we have had in the last year.

    Unless there is a really, really, really big shake (8 plus) to give you enough warning to do anything useful (e.g. to pull your trousers up if are were using the toilet), and thankfully really big shakes are really rare!

  6. MrB says:

    The door frame thing is kinda a myth. The door can come back and nail you, or you might end up blocking an exit. Best to always get under a table.
    See #6 here

    http://www.consrv.ca.gov/index/Earthquakes/Pages/qh_earthquakes_myths.aspx

    I dont want any of my fellow HaD pals getting bruises..or dead.

  7. Ross says:

    Fish thanks make a good P wave detector.
    I had a camera setup on a marine tank and you can see the fish hide as the p waves hit before the main waves shake the tank.

    4.8 aftershock

    4.9 Aftershock

    6.3 aftershock
    – No power/video, earthquake detector smashed all over the floor.

  8. fartface says:

    And every single “p wave detector” I have seen fails to work around any freeways, highways, city streets, or railways.

    Far too much heavy equipment make “p waves” and trucks slapping a highway seam makes p waves.

  9. Andrea says:

    Hi,
    I have uploaded a new video about the sensor you see at the top of this page. The mechanics is the same, but it looks more sensitive because I’ ve improved the alarm circuit.

  10. John says:

    Hey – I live in “Middle of Nowhere, Virginia” please have a little respect.

  11. morganism says:

    actually, get into an interior corner of the room, and pull a table over you.

    doorways dont cut it.

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