Earthquakes risk in Arizona

Earthquake Characteristics in Arizona

Arizona is not typically the first state that comes to mind for earthquake risk, but it does sit within a region of ongoing fault activity. The USGS Earthquake Hazards Program assigns Arizona a level 2 earthquake risk on a 5-point scale, meaning the overall hazard is relatively low to moderate. Most of the state's seismic activity is related to the Basin and Range Province, where the earth's crust is stretching and fault lines remain active.

The areas most exposed to ground shaking are the northwestern part of the state near the Arizona–California border and the southeastern region along the border with Sonora, Mexico. In 1887, a major earthquake centered in Sonora—estimated at magnitude 7.6—caused shaking and minor damage in southern Arizona communities such as Tucson and Bisbee. Smaller earthquakes occur occasionally throughout the state, but damaging quakes are infrequent when compared with states like California or Nevada.

Earthquakes can happen at any time of the year, and there is no "earthquake season" like the monsoon or winter storms. Arizona's known active faults, such as the Sevier fault zone in the north and the Pitaycachi fault in the southeast, are reminders that the ground can shake without warning. Because the state's building codes have evolved over decades, older homes are more likely to suffer damage than newer structures designed with seismic safety in mind.

How It Affects Homes

Even a moderate earthquake can cause damage to Arizona homes. The most common problems include cracks in drywall and masonry, shifting of foundation slabs, and toppling of unsecured furniture or water heaters. Homes built before modern building codes may be more vulnerable, especially those with unreinforced masonry walls or cripple walls. Mobile homes and houses not bolted to their foundations are especially at risk of sliding off supports during strong shaking.

Damage can also extend to utilities and structural elements: broken windows, torn gas lines, and displaced chimneys are all possibilities. An earthquake can also trigger small rockfalls in hillside neighborhoods or cause soil settlement on unconsolidated ground. Even if the structure remains intact, the contents can cause injuries or block exits, which is why securing heavy items matters.

In terms of insurance, standard homeowners insurance policies generally do not cover earthquake damage. You may be able to purchase a separate earthquake policy or an endorsement from your insurer. The FEMA Earthquake Safety page advises homeowners to review their coverage and consider earthquake-specific protection, particularly if you live in an area with higher shaking potential. Speak with your insurance agent to understand your policy and decide whether an earthquake rider is worth the cost.

How to Prepare Your Home

Preparation is important because shaking can happen without warning. The following steps are based on guidance from Ready.gov and FEMA and can help reduce damage and protect your family:

• Secure heavy furniture such as bookcases, cabinets and televisions to wall studs with straps or brackets.
• Install strong latches on kitchen cabinets to prevent contents from flying open.
• Anchor your water heater to wall studs to keep gas or electric lines from rupturing.
• Check your home's foundation for existing cracks and consult a contractor if you see signs of structural issues.
• Store breakable items in low, closed cabinets and use putty or museum gel on collectibles.
• Prepare an emergency kit with water, non-perishable food, flashlights, batteries and first-aid supplies.
• Create a family communication plan so everyone knows where to meet after an earthquake.
• Learn how to drop, cover and hold on, the recommended action during earthquake shaking.
• If you live in a mobile home, make sure it is properly tied down to its foundation according to state guidelines.
• Inspect your chimney for loose bricks and repair any weak spots before they become a hazard.

Frequently Asked Questions

How strong are earthquakes in Arizona?

Most earthquakes in Arizona are small—below magnitude 3.0—and go unnoticed. However, the state has experienced larger events in the past, including the 1887 Sonoran earthquake, and scientists cannot rule out future moderate earthquakes. The USGS maps active faults that can produce ground shaking with magnitudes above 5.0.

Does Arizona have earthquake insurance?

Earthquake coverage is not included in standard homeowners insurance policies. Arizona residents can often purchase a separate earthquake insurance policy from their insurer or through a specialty provider. It is important to read the policy carefully, as deductibles can be a percentage of the home value. Check with your agent to understand your options and what the policy covers.

What should I do during an earthquake?

Follow the guidance from Ready.gov: drop to your hands and knees, cover your head and neck with your arms, and hold on until the shaking stops. If you are indoors, stay there and avoid doorways unless you are near one. Do not run outside during shaking, and do not use elevators. If you are outside, move to an open area away from buildings, trees, and utility wires.

Official Resources

• Arizona Department of Emergency and Military Affairs
• USGS Earthquake Hazards Program
• Ready.gov – Earthquakes
• FEMA Earthquake Safety