Stone was part of an all-star cast of scientists and public safety officials assembled by the city of La Cañada Flintridge to address the threat of dangerous flooding and erosion in the wake of the Station fire, and related mitigation efforts.
Panelists included Dr. Lucy Jones and Dr. Susan Cannon of the United States Geological Survey (USGS), Los Angeles County Fire Asst. Chief Johnny Jee and Los Angeles County Sheriff’s Capt. David Silversparre.
Cannon, an preeminent expert on debris flow, said the USGS has devised empirical and statistical models to help predict the probability of debris flow and the volume of potential debris flow in the San Gabriel Mountains.
The scientists tested the models with two scenarios, an intense three-hour duration rainstorm, and a moderate 12-hour duration rainstorm. In both cases, Cannon explained, there was a probability of 80% that the rainfall would result in substantial debris flow.
“If you live in a dangerous place and it’s raining it is better to leave in advance,” Cannon said. “One possible combination too is if we are having one big long soaking rain and there is a burst of rainfall on top of that, that is something that should be a heads up.”
The foothills are no stranger to mudslides, Cannon said. The most significant incident took place on Dec. 31, 1933, when, following a massive rainstorm, mudslides wiped out 500 homes and killed 30 people.
Under current conditions, Cannon said, a serious storm could send debris as far as Foothill Boulevard or beyond.
