Image by NOAA Center for Tsunami ResearchPredicted maximimum wave heights from MOST forecast model following the 2010 earthquake in Chile. Click to enlarge image
Animation by NOAA Center for Tsunami ResearchAnimation showing the predicted spread time and wave height following the 2010 earthquake in Chile. Apple Quicktime required to view. Click to start animation.
Image by CeNCOOS, data from NOAA Tides and Currents programTidal plot for February 26-28th at Monterey, CA indicating observed vs. predicted tides. The erratic water height changes at the tide station in the lower graph indicate the tsunami's arrival at 12:30PM on the 27th. Click to enlarge the image.
Image by CeNCOOS, data from NOAA Tides and Currents programTidal plot for February 27-28th at Monterey, CA displaying the water height residuals (observed - predicted). The affect of the tsunami can be seen beginning at 2030 GMT on the 27th. Click to enlarge the image.
Data from CeNCOOS StationTidal plot for February 25-March 4th at Moss Landing, CA displaying the water height residuals (observed - predicted). The affect of the tsunami can be seen beginning at mid-day on the 27th and continuing until March 3rd. Click to enlarge the image.
On the morning of February 27th, 2010, a 8.8 earthquake occurred just off the coast of Chile at approximately 21 miles below sea-level (see USGS report). The quake produced a Tsunami that quickly hit the mainland of Chile and nearby islands, claiming lives and damaging property. The tsunami waves spread in all directions throughout the Pacific Ocean, coming ashore in several nations within 12 hours, but were smaller than predicted by NOAA (see image and animation on right column). NOAA uses NDBC Deep-ocean Assessment and Reporting of Tsunamis (DART) ocean buoys to measure wave heights and predict tsunami waves as they move across the ocean. However, DART buoys are few and far apart in the vast expanse of the Pacific, making accurate predicitions more difficult.
Damage due to tsunami's generated by this earthquake was generally minor outside of South America, with tsunami waves and ocean surges relatively small. Ocean waves were large in California on February 27th but were mostly generated from storms, unrelated to the Tsunami, leading to confusion as to the source of the waves. However, video of the tsunami in California did show the clear arrival of the modest tsunami surge:
- View time-lapse video of first 3 hours of tsunami at Crescent City on YouTube
- View tsunami arrival at Santa Cruz harbor on YouTube (Video 1) (Video 2) (Video 3).
The small tsunami can be detected in California by examining tidal plots from February 27th at coastal tide stations. The predicted tidal change (without tsunami impact) can be compared to the observed tidal change (with tsunami surge) to assess how much of an affect the tsunami had on the coast. The difference in water height (observed minus predicted) shows the tsunami arrival at tide stations (see image on right column for the Monterey, CA tide station). At one example tide station (Monterey, CA) the tsunami surge seems to have caused a maximum water level increase of nearly 0.8 feet above and a decrease of nearly 1.2 feet below the normal tide cycle (see image on right column). Another station (Moss Landing, CA) slightly more protected (inside Monterey Bay and a harbor mouth) showed a similar pattern and timing to Monterey Bay, but a less extreme minimum height for the tsunami surge (see image at right column bottom).
The water level graph from the Moss Landing station also demonstrates the long lasting affect of the tsunami. The dynamic water level (rising and falling faster than normal tides) continued for approximately four days after the initial tsunami wave arrived in this area. This phenomenon, known as a seiche, is similar to water in a bathtub continuing to slosh up and down after a person inside stops moving to disturb the water. A seiche can occur in totally enclosed or partially enclosed (like Monterey Bay) bodies of water. The cause of seiches can be several, but tsunami's are known to produce this effect. The waves of a seiche are referred to as 'standing waves' because they only move up and down, not forward like typical wind (or tsunami) produced waves in the open ocean.
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