COSTA MESA — What caused a 10-ton tree to fall on a woman's car while she waited at a stop light remained unclear to public safety officials and seismic and horticultural experts Friday.
But theories — from moist soil to trimmed roots to this week's earthquake — emerged from the tragedy that claimed Haeyoon Miller, 29, who died following the impact on 17th Street and Irvine Avenue on Thursday afternoon.
A 3.5 earthquake that took place off Newport Beach about 2:56 a.m. Thursday may have played a role, though there easily could have been other contributing factors, according to Lisa Grant Ludwig, a UC Irvine seismologist.
About 380 people in Costa Mesa reported feeling the earthquake on the U.S. Geological Survey site, according to Ludwig.
"[That's a] good indication right there that that location was shaken relatively strongly," she said. "It's possible."
But soil conditions, whether the ground was wet or slanted, and the health of the tree, are all potential factors that could have felled the 50-foot blue gum eucalyptus, she said.