Earthquake Risk
Environmental Risk Factor
Earthquake risk affects millions of Americans living near active fault lines across the country. While California and Alaska have the most frequent earthquakes, significant risk also exists in the Pacific Northwest from the Cascadia Subduction Zone, the New Madrid Seismic Zone in the central US, and along the Wasatch Front in Utah. Building codes and construction quality significantly affect earthquake vulnerability. Older buildings and unreinforced masonry structures are most at risk. The potential for catastrophic damage from a major earthquake in a densely populated area remains one of America's highest-consequence natural hazard risks.
How It's Measured
Earthquake risk is assessed using USGS seismic hazard maps that show the probability of exceeding various ground motion levels. Factors include proximity to active faults, historical earthquake frequency, maximum expected magnitude, soil type (which affects ground shaking amplification), and building vulnerability based on age and construction type. The Modified Mercalli Intensity Scale describes observed effects, while magnitude measures energy released. We also consider local building code enforcement and seismic retrofit requirements.
Health Effects
- ⚠️Crush injuries from structural collapse
- ⚠️Injuries from falling objects and broken glass
- ⚠️Secondary fire injuries from damaged gas lines
- ⚠️Mental health trauma and PTSD from major events
- ⚠️Waterborne disease from damaged water and sewer systems
- ⚠️Long-term displacement stress from damaged housing
Data Sources
- 📊USGS National Seismic Hazard Model
- 📊FEMA Hazus earthquake loss estimation
- 📊State geological survey fault maps
- 📊ANSS earthquake monitoring network
How to Protect Yourself
- ✓Secure heavy furniture, water heaters, and appliances to walls
- ✓Know how to shut off natural gas, water, and electricity
- ✓Keep emergency supplies including water, food, and first aid for 72 hours
- ✓Practice Drop, Cover, and Hold On
- ✓Consider earthquake insurance if you live in a high-risk zone
- ✓Have your home evaluated for seismic retrofit if built before modern codes