Starting in the late 1980s, magazines like Hit Parader started to use the terms "thrash" and "thrash metal" interchangeably for speed metal. The dumb kids who were buying Pantera CDs really got into this and started repeating it. Pantera is more popular (like Whitney Houston or Madonna) than underground thrash, so that was what the media parroted in its usual useless manner.
Thrash is not Speed Metal or "Thrash Metal"
Of interest to fans of:
* Cryptic Slaughter
* Fearless Iranians From Hell