Seismic research reveals active faults in Birch Bay area

Published on Wed, May 9, 2012 by Jeremy Schwartz

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Recently released geologic research into the Birch Bay area has uncovered previously unknown seismic faults, but the geologists behind the study say the findings are not cause for alarm.

Researchers with the U.S. Geological Survey (USGS) have spent the past five years poring over aerial laser mapping data for Birch Bay and the Sandy Point area south of Point Whitehorn. Brian Sherrod, one of the four USGS geologists who conducted
the research, said the two previously undiscovered active faults in the area do not significantly increase the risk of a serious earthquake in Birch Bay or Blaine. Rather, the new information gives geologists a better understanding of how the area was formed.

“The chances of having a big earthquake is very, very small,” Sherrod said.

The research revealed the coastline of Birch Bay has been uplifted by an earthquake in the 6.5 to 7 magnitude range at least twice within the last 6,000 years. Sherrod said the remnants of this geological upheaval can be seen in the elevation change along the northeast portion of Birch Bay Drive. That portion of the road used to be a beach while the golf course just to the south was a tidal flat.

“What you’re looking at is the deformation from [an] earthquake,” Sherrod said.

While the faults are described as still active, Sherrod explained this just means they’ve experienced seismic activity in the last 10,000 years. The faults run roughly parallel, with one stretching from Birch Bay State Park along the coastline to Drayton Harbor and the other running just south of Sandy Point.

While the faults do not necessarily increase the earthquake risk, no community along a fault line is ever completely free from danger, Sherrod said. A relatively shallow 6.5 magnitude earthquake, the strongest temblor the new faults are able to produce, would still be incredibly devastating.

“It makes us aware that we live in earthquake country,” Sherrod said.