When we think about earthquakes in the United States, the first state that comes to mind is California. But there are many regions across the country that are susceptible to frequent earthquake activity, and many more that have the potential to be affected.

Most homeowners insurance policies and renters policies do not cover earthquakes as part of their standard coverage. If you wish to be covered for this risk factor, you’ll typically have to purchase earthquake insurance separately, either as an endorsement to your basic coverage, or sometimes it is necessary to purchase a separate policy. Depending on what the risk is in your area, additional coverage could be inexpensive — or quite pricey.

Earthquakes and measurement

The United States Geological Survey (USGS) reports that earthquakes pose a “significant risk” to residents in 39 states. Earthquakes happen when fault lines deep below the earth’s surface release energy that has built up, caused by pressure between rocks as the earth’s crust shifts. This release of energy can happen at any time; there is no “earthquake season.”

The amount of shaking that results is often reported using the Richter Scale, which assesses the magnitude of a quake on a scale from 1–9 (or greater). A magnitude 1 earthquake would barely be felt, while any earthquake above 6 is considered “strong,” meaning even well-built structures will experience damage. You might also see reports referencing the Mercalli Scale. This scale measures the effects, or damage done by, an earthquake.

What are the risks in the U.S.?

The fault line we hear about most often is the San Andreas Fault, which is located in California. Because this fault is quite active, California experiences frequent earthquakes, of varying magnitude. Further north, Alaska and Washington are also in an earthquake-prone zone — the entire Northwest is considered to be seismically active, and earthquakes in this region, although less frequent, can be of great magnitude. In 1964, a magnitude 9.2 earthquake hit Alaska; to date this is the strongest recorded earthquake in the United States.

Other regions that we think of less often as earthquake zones are also at risk. The New Madrid fault line, which stretches through the center of the country, includes southeast Missouri, Arkansas, Illinois, Kentucky, and Tennessee. In 1811 to 1812, three very strong earthquakes, estimated to be around magnitude 8 on the Richter scale, occurred on the New Madrid fault line.

Other risks and earthquake insurance

Earthquakes can trigger secondary events, such as tsunamis, landslides, and fires. Older buildings, especially unreinforced masonry such as brick, can be far more susceptible to damage than newer structures that are built to seismic codes.

The Insurance Information Institute notes that the potential costs associated with damage due to earthquakes is rising, attributed to increased building in seismic areas, and “the vulnerability of older buildings.” They also note an increase in earthquakes in areas where the disposal of wastewater from hydraulic fracturing is common.

Earthquakes are common — there are around 20,000 in the United States every year according to the USGS. The majority of these are quite small and do little to no damage. Large, damaging quakes are less common, but depending on the intensity and location, can cause significant property damage.

Premium costs and deductibles can vary widely from one carrier to another. If you’re interested in earthquake insurance, talk to your agent or carrier about what options are available to add it to your policy.

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