Earthquakes risk in New Hampshire

Earthquakes in New Hampshire: what makes them different

New Hampshire is not California, but it is not seismically silent either. The state sits within the Northeast seismic zone, a region hundreds of miles from any plate boundary where earthquakes occur because of stresses inside the North American plate itself. The USGS Earthquake Hazards Program records small earthquakes across New England every year, and New Hampshire has a documented history of felt and damaging events.

The best-known example is the December 1940 earthquake centered near Ossipee, in the state's Lakes Region, estimated at roughly magnitude 5.5 — strong enough to crack walls and topple chimneys. Earlier, the 1755 Cape Ann earthquake off the Massachusetts coast, estimated in the magnitude 6 range, shook much of what is now New Hampshire, and colonial records describe several strong shocks felt in the region. A more recent reminder came in 2012, when a magnitude 4.0 earthquake near Hollis, Maine was felt widely across the state.

One feature of eastern earthquakes matters a great deal for homeowners: they are felt over much larger areas than western earthquakes of the same size. The region's cold, dense, ancient bedrock — including New Hampshire's granite — carries seismic waves efficiently, so a moderate quake near Ossipee may be felt in Boston, Vermont and southern Maine. The good news is that most New Hampshire homes are wood frame rather than unreinforced masonry, so shaking often causes less structural damage than a comparable California event.

Earthquakes are not seasonal, but the consequences can be. A winter quake that damages a chimney or gas line arrives in the middle of heating season, with snow on roofs and a higher chance of power outages in freezing temperatures.

Risk is not uniform across the state. The strongest historical activity has been recorded in the central Lakes Region around Ossipee and Wolfeboro, and New Hampshire Homeland Security and Emergency Management treats earthquakes as a statewide hazard with pockets of higher risk. Shaking tends to be amplified in areas underlain by thick, soft glacial sands and clays, including parts of the Merrimack and Connecticut River valleys and sections of the coastal plain. Older downtowns built with brick and stone face more damage potential than newer wood-frame subdivisions.

How it affects homes

Most earthquake damage in New Hampshire would come from shaking rather than ground rupture. Typical problems in eastern U.S. earthquakes include:

• Cracked plaster, drywall and exterior finishes, often around door and window openings.
• Chimney damage — unreinforced brick and stone chimneys are among the most vulnerable parts of an older New England home and can crack, shift or fall.
• Foundation cracks, especially in older stone or lightly reinforced concrete, and separation where a house is not anchored to its foundation.
• Toppled water heaters, furnaces and appliances, plus broken gas connections that create fire risk.
• Interior damage from falling bookcases, televisions, mirrors and heavy items.
• Aftershocks, which can further damage already weakened structures.

Insurance considerations. A standard homeowners, renters or condo policy does not cover earthquake damage. Coverage is normally added as a separate earthquake endorsement or a stand-alone policy. In New Hampshire, earthquake coverage is generally available and premiums are typically far lower than in high-hazard states such as California, but the deductible is often a percentage of your dwelling coverage rather than a flat dollar amount, which means a substantial out-of-pocket cost before benefits begin. Read exclusions carefully — masonry veneer, chimneys and detached structures such as garages and sheds are sometimes treated differently. Fire damage that follows an earthquake is generally covered if your policy covers fire, but confirm that with your agent. Federal disaster assistance, when it is available, is not a substitute for insurance.

How to prepare your home

Retrofitting a New England home for earthquakes is mostly about keeping the structure together and preventing secondary hazards such as fire and falling objects.

1. Anchor and brace the structure. Have a licensed contractor or structural engineer confirm that the house is bolted to its foundation and that cripple walls in the basement or crawlspace are braced with plywood.
2. Deal with the chimney first. Have a mason inspect, brace or rebuild unreinforced brick or stone chimneys; strapping and reinforcement greatly reduce the chance of collapse.
3. Strap the water heater. Secure it to wall studs with metal straps and use flexible connectors for water and gas lines.
4. Control gas and fire risk. Install flexible gas appliance connectors, consider an automatic seismic gas shutoff valve, and keep a wrench near the meter so you can shut gas off manually.
5. Secure furniture and contents. Anchor bookcases, shelving, dressers, televisions and mirrors to walls, use cabinet latches, and store heavy items on lower shelves.
6. Plan and practice. Teach everyone in the household to Drop, Cover and Hold On, choose a safe spot in each room, and keep sturdy shoes and a flashlight beside each bed.
7. Build a kit. Store water, non-perishable food, medications, a first-aid kit, a battery or hand-crank radio and extra flashlights, plus copies of key documents.
8. Review your coverage. Ask your insurer what an earthquake endorsement would cost and what the deductible would be.

Frequently asked questions

Does New Hampshire actually get earthquakes?

Yes. The USGS records earthquakes in and around New England every year, though most are too small to feel. Damaging earthquakes are uncommon, but the state has experienced them: the 1940 Ossipee earthquake, estimated at about magnitude 5.5, is the strongest on record here, and moderate events such as the 2012 Hollis, Maine earthquake were felt across New Hampshire. That history is why the state plans for earthquakes as a real, if infrequent, hazard.

Is earthquake insurance worth it in New Hampshire?

That depends on your home, your equity and how much repair cost you could absorb on your own. Because New Hampshire's risk is moderate rather than severe, premiums are usually modest compared with high-hazard states, but deductibles are often a percentage of dwelling coverage. Compare the cost of an endorsement with the repairs you would most likely face — chimney rebuilding, foundation work or replacing contents — and ask your agent what the policy excludes.

What should I do during an earthquake in New Hampshire?

Indoors, Drop, Cover and Hold On under a sturdy table or against an interior wall, away from windows and tall furniture; if you are in bed, stay there and protect your head with a pillow. Outdoors, move away from buildings, streetlights and power lines. If you are driving, pull over away from bridges and overpasses. Afterwards, check for injuries and gas leaks — if you smell gas, leave the building and call for help from outside — and expect aftershocks.

Official resources

• New Hampshire Homeland Security and Emergency Management — state hazard information, preparedness guidance and emergency alerts.
• USGS Earthquake Hazards Program — real-time earthquake maps, historical catalogs and hazard information for New England.
• Ready.gov — Earthquakes — federal guidance on what to do before, during and after an earthquake.
• FEMA Earthquake Safety — risk management and mitigation resources for homeowners and communities.