Which guitar technique did Eddie Van Halen use for his breakthrough song "Eruption"?

The album [Van Halen, 1978] included songs now regarded as Van Halen classics, like "Runnin' with the Devil" and the guitar solo "Eruption", which showcased Eddie's use of a technique known as "finger-tapping".

Tapping is a playing technique that can be used on any stringed instrument, but which is most commonly used on guitar. The technique involves a string being fretted and set into vibration as part of a single motion. This is in contrast to standard techniques that involve fretting with one hand and picking with the other.