1st WA DNR Study of Rainier Lahar Damage-- up to $40 Billion

Every 500-1000 years the slopes of Mount Rainier produce liquefied mud flows called lahars that can flow like rivers but have a density similar to liquid concrete. Based on the last Electron Mudflow ~550 years ago, and using HAZUS software, the DNR released a new report that estimates potential damage to property (but not life) based on these lahars for the first time.

The DNR has simultaneously released a new map product at https://fortress.wa.gov/dnr/geology/?Site=lahar that allows exploration of where these lahars may flow.

A News Tribune story states that state geologist Dave Norman believes “it’s unlikely a lahar would fill all six major drainages that flow from Mount Rainier.”