Lessons from California Mudslides: Science's Credibility Is At Stake

For applied scientists—that intrepid cadre who get their hands dirty in the sometimes dangerous world beyond the ivory tower, participating in difficult decisions with little time and major consequences—getting the right answer is only half the battle. Predicting debris flows—you might know them better as mudslides— is literally more difficult than rocket science, involving deep concepts in complexity theory like nonlinear feedbacks, fractal dynamics, and self-organized criticality. Yet they’re common in mountain regions worldwide, and the associated destruction can be spectacular: One night in 1999, debris flows on Venezuela’s Caribbean coast left 30,000 dead. Early media reports pointed to simple explanations: For example, mandatory evacuation apparently was only undertaken in steep headwater areas, with less compelling voluntary evacuation notices issued for flatter downstream locations where the debris flows, running out from the mountains, ultimately took their heaviest toll. The choice by some Montecito residents in the voluntary evacuation zone to decline science-based advice may point to a more fundamental issue, with implications far beyond southern California.