Burson was mentored by Hanna-Barbera voice artist Daws Butler, and when
Butler died in 1988, Burson took over Butler's roles as Yogi Bear,
Huckleberry Hound, Snagglepuss, Quick Draw McGraw and other characters
in H-B's stable. Burson also replaced Mel Blanc as Bugs Bunny, Foghorn
Leghorn, Pepe LePew and others. He even succeeded Jim Backus as Mr.
Magoo.
Burson also worked as an announcer, and may be best known in that role
for his early work on a Dianetics commercial that ran and ran and ran
for years. (This was the one with the volcano.)
You'll find a sad mention at the link of Burson's unsuccessful struggle
with alcoholism.
<http://www.newsfromme.com/archives/2008_08_01.html#015596>
Here's a sample of Greg Burson's work in cartoons and commercials:
<http://www.newsfromme.com/archives/2008_08_01.html#015597>
One of the volcano spots, from 1989: