Hurricane Helene Set Up Future Disasters, from Landslides to Flooding -- Cascading Hazards Like These Are Now Upending Risk Models
An Intensifying Threat in a Changing World
These risks present challenges for everything from emergency planning to home insurance. After repeated wildfire-mudslide combinations in California, some insurers pulled out of the state entirely, citing mounting risks and rising costs among the reasons.
Cascading hazards are not new, but their impact is intensifying.
Climate change is increasing the frequency and severity of wildfires, storms and extreme rainfall. At the same time, urban development continues to expand into steep, hazard-prone terrain, exposing more people and infrastructure to evolving risks.
The rising risk of interconnected climate disasters like these is overwhelming systems built for isolated events.
Yet climate change is only part of the equation. Earth processes – such as earthquakes and volcanic eruptions – also trigger cascading hazards, often with long-lasting effects.
Mount St. Helens is a powerful example: More than four decades after its eruption in 1980, the U.S. Army Corps of Engineers continues to manage ash and sediment from the eruption to keep it from filling river channels in ways that could increase the flood risk in downstream communities.
Rethinking Risk and Building Resilience
Traditionally, insurance companies and disaster managers have estimated hazard risk by looking at past events.
But when the landscape has changed, the past may no longer be a reliable guide to the future. To address this, computer models based on the physics of how these events work are needed to help forecast hazard evolution in real time, much like weather models update with new atmospheric data.
Thanks to advances in Earth observation technology, such as satellite imagery, drone and lidar, which is similar to radar but uses light, scientists can now track how hillslopes, rivers and vegetation change after disasters. These observations can feed into geomorphic models that simulate how loosened sediment moves and where hazards are likely to emerge next.
Researchers are already coupling weather forecasts with post-wildfire debris flow models. Other models simulate how sediment pulses travel through river networks.
Cascading hazards reveal that Earth’s surface is not a passive backdrop, but an active, evolving system. Each event reshapes the stage for the next.
Understanding these connections is critical for building resilience so communities can withstand future storms, earthquakes and the problems created by debris flows. Better forecasts can inform building codes, guide infrastructure design and improve how risk is priced and managed. They can help communities anticipate long-term threats and adapt before the next disaster strikes.
Most importantly, they challenge everyone to think beyond the immediate aftermath of a disaster – and to recognize the slow, quiet transformations that build toward the next.
Brian J. Yanites is Associate Professor of Earth and Atmospheric Science. Professor of Surficial and Sedimentary Geology, Indiana University. This article is published courtesy of The Conversation.
