United States Geological Survey says it will now include earthquakes caused by human activity on its seismic risk maps.
It follows a sharp rise in earthquakes linked to wastewater disposal wells used by the oil and gas industry in Oklahoma.
Last year the state experienced more than 900 earthquakes measuring magnitude 3 or greater, compared with just two of similar size in 2009.
The seismic risk maps are used by emergency management officials as well as major engineering and design associations to guide how strong to construct buildings.
