A still picture on the TV news last night showed the rear section of the engine missing large bits of the upper section. That section is only fairly thin and if melting away would cause that "sparkler' effect. Loved the comment on the news from one of the pax "Just like a sparkler ...bit a BIG one"
There also looked like a big hole in the nacelle at around the 2 o'clock position where something appears to have come out!
Edit ..found the picture on
Incident: Cobham RJ1H at Perth on Apr 29th 2014, uncontained engine failure