Friday, September 18, 2015

Chilean Tsunami Strikes Crescent City

The California Crescent City, not New Orleans. Yesterday I reported on a huge earthquake, 8.3 on the Richter Scale, which struck Chile late Wednesday, sending tsunami warnings across the Pacific Ocean.  The earthquake apparently caused relatively little damage in Chile, with only one person reported killed initially. Good news. And there is no further reports of tsunami damage, even more good news, since tsunamis are often more damaging than the earthquakes that spawn them

However, I looked at the tide gauge from Crescent City California, and I believe you can see the signal from the quake:

Look at the odd wiggles and jumps in the red line starting at the end of the third peak on Thursday, you can see several quick changes in tide height that stand out. If you look at the green line, the anomaly (Observed height minus the astronomical tide+the wind predictions, you can see a series of wiggles which I believe are the long period waves from the earthquake (tsunami). You can see similar, but less extreme waves in the tide gauges from a number of stations from California to Alaska. These waves were only a few inches tall, and were likely not apparently to viewers, but may have caused odd currents in the harbor, similar to, but smaller than those caused by the Japanese megaquake in 2011:

Crescent City is particularly vulnerable to tsunami damage by virtue of it's location on the exposed coast, and underwater topography; tsunamis from the 1964 Good Friday Quake in Alaska destroyed much of the town's waterfront and killed 12 people.

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