House design · Structure and hazards: wind, earthquake, flood and wildfire · design-26

Design for earthquakes

Earthquakes shake the ground sideways. Heavy, brittle and poorly tied buildings fail first, and loose contents injure people.

How

Use the hazard level from design-24. In any seismic zone above the lowest category, have the structure engineered or follow a code path that covers your zone.
Earth walls: unreinforced adobe is prone to collapse even in low-intensity earthquakes. A common defect is the absence of ring beams. Use an engineered design or an earth standard (design-11).
Europe: design to EN 1998 (Eurocode 8) with your national annex. US: ASCE 7 values from the ASCE Hazard Tool. New Zealand: NZS 4297 to 4299 for earth buildings.
Strap water heaters so they cannot move, and have flexible connections fitted where gas lines meet the house (FEMA).
Move heavy or large items stored over 4 feet (about 1.2 m) up to lower shelves or the floor. Fit latches on cabinets and drawers.
Attached garages with rooms above often have less bracing at the vehicle opening; have them checked. Hillside homes can pull away from their foundation and may need added anchoring.
Off-grid heavy items need restraint too: masonry heaters (thermal-8), roof or stand tanks and battery racks. Ask the engineer to detail their fixings.

Safety: Unreinforced heavy walls can collapse without warning in an earthquake.