The National Weather Service in Eureka issued a coastal flood warning on Thursday in anticipation of anomalous high tides that hit early Friday. While there were few issues caused by the flooding, the king tides offer a preview of what future sea level rise could mean for Eureka and the rest of Humboldt Bay.
“This is about one foot higher than a typical high tide,” said Jennifer Kalt, director of the nonprofit Humboldt Baykeeper. “With one foot of sea level rise, what we saw today will be the average monthly high tide.”
In fact, the astronomical tide event was even higher than expected as it reached a peak of 9.28 feet in the North Spit. But other fortunate weather factors helped mitigate any risk of damage from flooding.
Only within the past decade are geologists realizing that the area around Humboldt Bay is sinking due to tectonic subsidence. The average sinking is at nearly the same rate that sea levels are rising, compounding the effect and doubling the relative sea level rise. In contrast, Crescent City appears to be on a tectonic uplift that would minimize the effects of rising sea levels. And for better and for worse, the science at the core if this issue is still fairly new; the theory of plate tectonics only came to be understood in the past 75 years.
“A lot of this science is advancing,” said Kalt. “10 years ago, no one knew that the Humboldt Bay area was sinking so rapidly due to tectonic subsidence.”
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