Earthquakes risk in Montana

Earthquake characteristics in Montana

Montana is one of the most seismically active states in the U.S., particularly in its western half. The state sits within the Intermountain Seismic Belt, a broad zone of frequent earthquake activity that extends from northwest Montana down through the Rocky Mountains. This means that while earthquakes can occur anywhere in Montana, the highest risk is concentrated in the western region.

Areas of greatest exposure include the Flathead Lake valley, the Helena and Missoula areas, the Gallatin Valley near Bozeman, and the greater Yellowstone region. Some of Montana's most notable earthquakes include the 1959 Hebgen Lake earthquake (magnitude 7.2), which caused significant damage and triggered a massive landslide, and the 1935 Helena earthquakes, which damaged much of the city. More recently, a magnitude 5.8 earthquake struck near Lincoln, Montana, in 2017, reminding residents that damaging quakes can happen even in areas not traditionally considered high-risk.

Earthquakes in Montana occur without regard to seasons—they can strike at any time of year. The primary hazard is ground shaking, which can be strong enough to damage buildings and infrastructure. Secondary hazards include landslides, rockfalls, and soil liquefaction in susceptible areas, particularly along river valleys and lake shores. While eastern Montana experiences fewer earthquakes, it is not immune; the USGS National Seismic Hazard Map shows that all of Montana has some level of earthquake risk.

How it affects homes

Earthquake damage to homes in Montana typically results from ground shaking. Common effects include cracked foundations, broken chimneys, shifted walls, and damaged rooflines. Older homes, especially those built before modern building codes, are more vulnerable. Unreinforced masonry (brick or stone) homes and those not properly bolted to their foundations can suffer severe structural damage. Inside, unsecured water heaters, appliances, and heavy furniture can topple, causing injuries and additional damage.

Even moderate earthquakes can cause costly damage. For example, the 2017 Lincoln earthquake caused damage to some homes and businesses in the surrounding area. In areas with certain soil types, liquefaction can cause homes to sink or shift. Landslides triggered by shaking can also threaten homes on slopes.

Standard homeowners insurance policies do not cover earthquake damage. To protect your home, you would need a separate earthquake insurance policy or an endorsement. In Montana, earthquake coverage is available from many private insurers. Policies typically have a separate deductible, often expressed as a percentage of your home's insured value (e.g., 10–15%). Before purchasing, review the policy carefully to understand what is covered, including dwelling, personal property, and additional living expenses if your home becomes uninhabitable.

How to prepare your home

Taking steps to strengthen your home and secure its contents can significantly reduce earthquake risk. Consider the following measures, many of which are recommended by FEMA and Ready.gov:

• Bolt your home to its foundation. If your home is not already bolted, hire a licensed contractor to install anchor bolts or plates. This is one of the most effective ways to prevent your home from shifting off its foundation.
• Brace cripple walls. If you have a raised foundation, reinforce the short walls between the foundation and the first floor with plywood or metal bracing.
• Reinforce chimneys. Unreinforced masonry chimneys can collapse. Have a professional evaluate and reinforce or replace your chimney if needed.
• Secure water heaters and appliances. Use straps or brackets to anchor water heaters to wall studs. Secure refrigerators, washing machines, and other large appliances with earthquake-resistant straps or brackets.
• Anchor heavy furniture and electronics. Attach bookcases, shelves, and TVs to wall studs. Use closed hooks or museum putty for hanging pictures and mirrors.
• Install cabinet latches. Use childproof or earthquake latches on kitchen and bathroom cabinets to prevent items from falling out.
• Create a disaster kit. Include water, non-perishable food, flashlights, a battery-powered radio, first-aid supplies, and medications. Ready.gov provides a detailed checklist.
• Practice "Drop, Cover, and Hold On." During an earthquake, drop to the ground, take cover under a sturdy table or desk, and hold on until shaking stops. If no cover is available, crouch against an interior wall and protect your head and neck.
• Have your home inspected. A licensed structural engineer or contractor can identify vulnerabilities and recommend retrofits specific to your home's construction type and location.

Financial assistance for retrofitting may be available through state or federal programs. Contact Montana Disaster and Emergency Services for more information.

Frequently asked questions

Are earthquakes common in Montana?

Yes. Montana experiences many small earthquakes each year, most too small to be felt. The western part of the state is particularly active due to the Intermountain Seismic Belt. While major damaging earthquakes are less frequent, they have occurred in the past and will occur again.

Does homeowners insurance cover earthquake damage?

No. Standard homeowners insurance policies typically exclude earthquake damage. You need a separate earthquake insurance policy or an endorsement to your existing policy. Many private insurers in Montana offer this coverage, but it usually comes with a separate deductible, often 10–15% of your home's insured value.

What should I do during an earthquake?

If you are indoors, drop, cover, and hold on. Get under a sturdy table or desk and protect your head and neck. Stay away from windows and exterior walls. If you are outdoors, move to an open area away from buildings, trees, and power lines. If you are driving, pull over to a clear spot and stay in your vehicle until the shaking stops.

Official resources

• Montana Disaster and Emergency Services – State agency for emergency preparedness, response, and recovery.
• USGS Earthquake Hazards Program – Real-time earthquake information, hazard maps, and research.
• Ready.gov – Earthquakes – Federal guidance on earthquake preparedness, including checklists and safety tips.
• FEMA Earthquake Safety – Resources for risk management, mitigation, and safety.