Not an EMP, but nature can do similar. We don`t have recordings of what a pole shift does.
https://www.history.com/news/a-perfect-solar-superstorm-the-1859-carrington-event
A Perfect Solar Superstorm: The 1859 Carrington Event | HISTORY
In 1859 a massive solar flare spewed electrified gas and subatomic particles toward Earth, wreaking havoc on telegraph networks.
https://www.history.com/news/a-perfect-solar-superstorm-the-1859-carrington-event