Watson Lecture: Michael Lamb Examines the Fire–Flood Cycle

In light of the fires that have burned throughout the Greater Los Angeles region, Michael Lamb, professor of geology, has revised the topic of his Watson Lecture.

Why do debris flows often occur after wildfires, and what can be done to forecast their impact? On January 29, 2025, at 7:30 p.m. PT in Caltech's Beckman Auditorium, Michael Lamb, professor of geology, will discuss the threat of debris flows in the steep, burned hills that border many Los Angeles-area communities.

In a public talk called "The Science of Post-Wildfire Debris Flows," Lamb, who studies the shape and evolution of Earth's surface as a geomorphologist, will discuss his team's latest research on debris flows, fast-moving torrents of water, mud, and rocks that are dangerous to life and property. Debris flows often occur after wildfires in a phenomenon known as the fire–flood cycle. This cascade of disasters has plagued California for more than a century.

"Earth's landscapes are dynamic, but change slowly over geologic time often with little notice from people," Lamb says. "But after wildfires in Southern California, floods can deliver a century's worth of erosion in a single event."

For more information on debris flow hazards please see the California Watershed Emergency Response Teams (WERTs) report online. A report on the Eaton Fire is available.

Starting at 6 p.m., members of Lamb's research group will be present to answer questions about their work.

On campus, Lamb runs a flume lab called the Caltech Earth Surface Dynamics Laboratory, where researchers have the ability to investigate water and sediment flow in a controlled environment. His studies on the mechanics of erosion, transport, and deposition of sediment extend beyond Earth to other planets, and he has been a member of the science team for several Mars rover missions. Prior to joining the Caltech faculty in 2009, Lamb earned a PhD in earth and planetary science from UC Berkeley.

The Watson Lectures offer new opportunities each month to hear how Caltech researchers are tackling society's most pressing challenges and inventing the technologies of the future. Starting at 6 p.m., join a community of curiosity outside Beckman Auditorium to enjoy food, drinks, and music together before the talk. Interactive displays related to the evening's topic will give audience members additional context and information. Guests are also encouraged to stay for post-talk coffee and tea as well as the chance to converse with attendees and researchers.

Learn more about the Earnest C. Watson Lecture Series and its history at Caltech.edu/Watson. Watson Lectures are free and open to the public.

Advance registration is full for this event. There will be a stand-by line. A recording will be made available after the live event.