[Coral-List] Uplifted coral reefs

[Serge Andrefouet]

Hi Gene,

Interesting. There are no doubts some areas were uplifted and I guess you 
have adequate ground-truthing around Nias, but these images alone would not 
demonstrate anything. The older one has a nice swell coming in (good surf 
that day in Nias I guess), and the later image has calmer seas. Also there 
may be a tide difference. The difference of signal along the crest can be 
only due to different set-up on the flats/crests and thus in differences in 
swell and tide, not uplifting. It is very common to see this on pair of 
images of the same site. No unambiguous changes on reefs detectable from 
space here, just different environmental conditions.

As a clear example of similar pseudo-changes, there are two samples of 
Landsat images of a section of Majuro atoll (Marshalls) during two 
different tide cycles, different south swell conditions and different dates 
on http://imars.marine.usf.edu/~serge/Majuro .

Cheers,

S.



A 04:55 PM 5/6/2005 -0400, Gene Shinn a écrit :
>There has been much discussion on the coral-list about tsunami effects on 
>coral reefs in Indonesia but how many know of the extensive reef areas 
>around Sumatra that were uplifted (100 percent mortality)
>as much as 2.5 meters by the more recent earthquake?  To see a portion of 
>the uplifted reefs, recently surveyed by USGS geologists, see the 
>satellite images at, 
>http://earthobservatory.nasa.gov/Newsroom/NewImages/images.php3?img_id=16892
>Gene
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Serge Andrefouet
UR Coreus - Institut de Recherche pour le Développement (IRD)
BP A5 - 98848 Nouméa cedex - Nouvelle Calédonie
Tél : (+687) 26 08 00 - Fax : (+687) 26 43 26 - andrefou at noumea.ird.nc