3 ms·

The wikipedia page mentions occurrences in the years 869 and 1888.

• almostnormal 3y ago
  Even back at those times earth quakes (2 miles/s) were a bit slower than the speed of light.
  • Izkata 3y ago
    I don't know about 1888, but I'm fairly sure that electrical infrastructure didn't exist over a thousand years ago.
    • lunarimiso 3y ago
      Well, with that attitude it didn't
      • wheelerof4te 3y ago
        It did exist before the Younger Drias period, though. Atlantians used it to power their space ships.