Nuclear bomb test or earthquake? How we tell the difference

The first 200 people to sign up at https://brilliant.org/stevemould/ will get 20% off an annual premium subscription. I use a slinky to show how we we're able to tell the difference between earthquakes and an underground nuclear bomb tests Visit my blog here: http://stevemould.com Follow me on twitter here: http://twitter.com/moulds Buy nerdy maths things here: http://mathsgear.co.uk