That figure, from all 50 states and Puerto Rico, is a sharp jump from the figure in 1994, when the Federal Emergency Management Agency estimated just 75 million Americans in 39 states were at risk from earthquakes.
The authors of the study, which included the U.S. Geological Survey, said the sharp increase in exposure to quake damage was largely because of population increases in areas prone to earthquakes, particularly California, said William Leith, a coauthor and senior science advisor for earthquake and geologic hazards at the U.S. Geological Survey.
“Significantly more Americans are exposed to earthquake shaking, reflecting both the movement of the population to higher risk areas on the West Coast and a change in hazard assessments,” Leith said in a statement.
Of the 150 million, more than 143 million were in the 48 contiguous states.
Authorities calculated the average financial loss to earthquakes in the lower 48 states is roughly $4.5 billion a year, mainly in California, Oregon and Washington state.
“Earthquakes remain an important threat to our economy,” Kishor Jaiswal, a research contractor for the USGS, said in a statement.