24 March 2010

Tsunami from Chile Quake Hits Ducie Atoll

The tsunami which moved westward from coastal Chile following the earthquake, was projected to hit Ducie Atoll within a few hours, according to projections issued by the Pacific Tsunami Warning Center, operated by the NOAA.

These are two projected times, giving the first time and then the Pitcairn Island group as a comparison...


A 5 meter wave hit Juan Baptista Island (Robinson Crusoe), according to the National Geophysical Data Center of the National Oceanic and Atmospheric Administration.

In response to the NOAA office, they provided this information in regards to the tsunami in the area of Ducie Atoll.

..."our forecast model did show a 0.17m maximum wave amplitude just east of Ducie Island in deep water. This is pretty big wave. If I use the Green's law to extrapolate the run-up at Ducie Island, it would be in the range of 1-2 meters. However, Ducie Island has a fringing reef, which dampens the wave energy (some studies show the reefs can reduce the run-up by as much as 40% or more). So the run-up at Ducie Island could have been somewhat less than 1-2 meters. This is just our estimate, in the absence of an inundation (fine-mesh) model for the Pitcairn Islands region."

Even a small tsunami would have washed the Atoll, which has a surface height of ca. 3.6576 m (12 feet) and is one 1/3 miles long, and a mile wide. Vegetation increases the overall height.

There is no information available on how the tsunami would have impacted any of the Pitcairns. The Tsunami Office commented that: "The only tsunami observations we have from the Chile 2010 tsunami near Pitcairn Island are from tide gauges in French Polynesia, Rikitea, Tahiti, Hiva Oa, and Nuku Hiva.."

This is a representation of the magnitude of the tsunami within the Pacific basin.
The maximum magnitude indicated is 1 meter.

Location map for Ducie Atoll, showing its location in the southern Pacific Ocean, at the east end of the Pitcairn Islands. Note that it is located within the region where the maximum magnitude of the tsunami occurred.
With the earthquake happening at ca. 3:30 a.m. local time, Ducie Atoll would have had impact within a few hours.

Current conditions at Ducie Atoll are unknown, as there are no residents on this little speck of a place, and the atoll is too remote to be regularly visited, and for any assessment to be made.

Ducie Atoll — with a land area of 0.7 km2 — is among the Pitcairn Islands, including Henderson, Pitcairn and Oeno Islands in the deep Pacific along the Tropic of Capricorn.

According to the National Geophysical Data Center, the last large tsunami that occurred in the region took place in 1946, when a 9.5 meter wave also was recorded as hitting Juan Fernandez Island.

1 comment:

Sue G. said...

Thanks for the info, Jim. Very interesting. --Sue and Scott Gardner, Lincoln, NE

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