Earthquakes risk in Idaho

Earthquake Risk in Idaho: What Homeowners Should Know

Idaho is located in a seismically active region where the Snake River Plain, Yellowstone hotspot, and Basin and Range extension interact. According to the Idaho Office of Emergency Management, most of the state's earthquake activity occurs along the Intermountain Seismic Belt, which runs from Montana through central Idaho and into Nevada. This belt includes several active fault zones, notably the Lost River and Sawtooth faults.

The USGS Earthquake Hazards Program tracks these faults and provides real-time earthquake data. Idaho's most significant historical earthquake was the 1983 Borah Peak earthquake (magnitude 6.9), which caused substantial ground deformation and damage in the central part of the state. More recently, earthquake swarms near Yellowstone National Park and eastern Idaho have reminded residents that seismic activity is common, although most events are too small to feel.

Earthquake risk in Idaho is not limited to a specific season. It is not caused by weather or temperature. Instead, risk is constant because the ground is always under tectonic stress. While the highest hazard areas are in the central and eastern regions, even western Idaho experiences occasional earthquakes. The USGS hazard map rates Idaho as a moderate risk overall, meaning that damaging shaking is possible but not as frequent as in states like California or Alaska.

How it affects homes

Earthquake shaking can damage homes in several ways. The most common structural damage occurs to foundations, masonry chimneys, and unreinforced walls. Older homes built before modern seismic codes are particularly vulnerable. In mountainous parts of Idaho, strong shaking can also trigger landslides that threaten hillside properties. In valleys with fill soil or high water tables, liquefaction can cause the ground to behave like a liquid, potentially sinking or tilting buildings.

Indoor hazards often cause more injuries than structural collapse. Unsecured water heaters, refrigerators, bookcases, and overhead light fixtures can topple or fall during shaking. Broken glass, gas leaks, and fire hazards add to the danger. The Ready.gov Earthquakes page emphasizes that taking simple steps to secure your home's contents is critical for safety.

Regarding insurance, earthquake damage is not covered by standard homeowners policies. Homeowners in Idaho must purchase a separate earthquake policy or add an endorsement to their existing coverage. Deductibles for earthquake insurance are often 10% to 25% of the dwelling limit, which is important to understand before buying a policy. The FEMA Earthquake Safety page explains how to evaluate your risks and consider retrofitting options. Reviewing your insurance annually with your agent is a prudent step.

How to prepare your home

You can reduce earthquake damage and personal injury by taking the following measures:

• Secure heavy furniture, such as bookcases, cabinets, and entertainment centers, to wall studs with L-brackets or flexible fasteners.
• Install positive latches on cabinet doors to prevent contents from spilling during shaking.
• Strap the water heater and other large appliances to wall studs with metal straps.
• Use flexible gas and water connectors for appliances to help prevent pipe breaks.
• Anchor chimneys and reinforce masonry walls with professional retrofitting if needed.
• Place breakable items, heavy objects, and sharp tools on lower shelves or inside cabinets.
• Hang mirrors and heavy picture frames away from beds and seating areas.
• Learn how to shut off the gas in case of a leak, and keep a wrench handy.
• Create an emergency kit with water, food, flashlights, batteries, a first-aid kit, and important documents.
• Practice 'Drop, Cover, and Hold On' drills with your household so everyone knows what to do.

These steps are endorsed by the Ready.gov and Idaho Office of Emergency Management. Even small retrofits like securing a water heater can prevent major damage and potential injuries.

Frequently asked questions

Are earthquakes common in Idaho?

Yes. Thousands of tiny earthquakes are recorded each year in Idaho and neighboring Yellowstone region, but most are too small to be felt. Moderate and large earthquakes are less frequent, but they have happened in historical times, such as the 1983 Borah Peak earthquake. The USGS maintains a list of recent activity that shows how common these events are.

What should I do during an earthquake?

The recommended action is to drop, cover, and hold on. Drop to your hands and knees, take cover under a sturdy table or desk, and hold on to it until the shaking stops. Stay inside if you are indoors; do not run outside, where falling debris can injure you. If you are in bed, stay there and cover your head with a pillow. More safety tips are available at Ready.gov.

Does homeowners insurance cover earthquake damage?

No, standard homeowners insurance policies do not cover earthquake damage. In Idaho, you need a separate earthquake policy or an endorsement to your current policy. Contact your insurance agent to discuss options and understand the deductible, which is usually a percentage of your dwelling coverage. The FEMA website offers guidance on earthquake insurance.

Official resources

• Idaho Office of Emergency Management
• USGS Earthquake Hazards Program
• Ready.gov – Earthquakes
• FEMA Earthquake Safety