BSI Risk Map

Quake Risk for Earthen Buildings

Check before you build.

Scientists update risk maps when they get more information. Most recent is best. If you can't find accurate local maps, check out our estimated risk maps. Our measurement units match those used in New Zealand for their unique standards-based earthen building code.

Download 170 kb map pdfs below:

Online risk information

GEM is an online global earthquake hazard map interactive viewer (excerpts shown below) for PGA (peak ground acceleration), a value used by engineers to determine Ss values.

GEM is based on a metric value of 10% probability in 50 years, while BSI follows the standard/English value also used by New Zealand of 2% probability in 50 years. These are approximate equivalents:

BSI/ standard/ English @ 2% in 50 years: GEM/ metric @ 10% in 50 years: New Zealand code allows:

Medium risk 0.25- 0.6 g 0.05- 0.12 g unreinforced on RC foundation

Higher risk 0.6- 1.7 g 0.12- 0.34 g reinforced on RC foundation

Many government web tools can give precise data for an address. Look for Ss (short period or 0.2 second) values that apply to low-rise buildings. Follow the links below for Australia, Europe, US, or Canada.

Australia

Australia updated their map in 2018. They may not have a web tool, but their seismic hazard map is online.

Europe

The EFHR's online hazard data access allows you to zoom in on a map. Type latitude and longitude, select SA 0.2, POE 2% in 50, rock, arithmetic. Turn on layers for roads.

United States

Use ATC's hazards by location app. After the address, choose seismic, and specify risk category II (unless it's a church or school) and site class D (hard ground unless it's very soft or bedrock). Look for the Ss number.

Canada

Use Natural Resources Canada's seismic hazard values tool. Type your latitude and longitude in, then click submit. Scroll down to see the top table (2%/50 yrs), then click on the 3rd column to the right (Sa 0.2).

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