Static Electricity is quite normal in Volcanoes Eruptions, But according to these Scientist who studied Mt. Redoubt Eruption January 2009, Stated what they where seeing in these eruptions after 1992 including Mt Redoubt, was what they called: "A New Kind of Lightning"!
"We saw lots of lightning - 20 to 30 minutes of lighting," said Thomas. "We saw even more lightning than we would typically see during a major thunderstorm." Not only was the amount of lightning unusual, but so was the kind of lightning coming from the volcano. "At the moment the eruption started, there were these sparks of lightning coming from the vent of Redoubt that only lasted 1 to 2 milliseconds," said McNutt, " This was a different kind of lighting that we have never seen before." http://www.insidescience.org/research/a_new_kind_of_lightning