Authorities said a large eucalyptus tree fell on Hyundai Accent on Irvine Avenue near 17th Street on the boundary line of Newport Beach and Costa Mesa on Thursday afternoon. She was stopped at a red light at the time.
Witnesses tried to help, but couldn't do much because of the massive size of the tree. By the time emergency crews were able to lift the tree, Miller had died.
It's still unclear what caused the tree to fall, but authorities say there's no evidence her car ever hit the tree.
Under a 2002 agreement with Costa Mesa, Newport Beach is responsible for maintaining the trees within the median. Officials say the fallen tree's canopy was last pruned in April.
Newport Beach officials are investigating what caused the tree to fall and said it will inspect all trees planted within the Irvine Avenue median.
The fallen tree was a 60-year-old Blue Gum Eucalyptus. Its total weight was estimated at 10 tons.