A 700-mile-long fault line that runs along the West Coast is overdue for a massive earthquake that scientists warn could sink parts of the US.
New research found that a 8.0 magnitude or higher quake along the Cascadia Subduction Zone, combined with rising sea levels, would cause coastal land to sink up to 6.5 feet within 30 minutes of a major tremor.
The team generated tens of thousands of earthquake models to estimate the potential range of earthquake-driven subsidence — sinking land — that can be expected from the next large Cascadia earthquake.
They determined that the most severe effects would hit southern Washington, northern Oregon and northern California, densely populated areas in the region.
This event would result in significant expansion of the coastal floodplain — an area with a one percent chance of flooding each year — increasing it from 35 square miles to 116.
If such a quake struck today, the researchers estimate that an additional 14,350 residents, 22,500 structures and 777 miles of roadway would fall within the post-earthquake floodplain, more than doubling flood exposure.
The Cascadia Subduction Zone has historically produced 8.0 or larger magnitude earthquakes every 400 to 600 years, with the last striking in 1700.
This suggests the ‘sleeping giant’ is poised for another big one soon.
