foreshortening as well as foldover, in some 
cases, even make topography effects more 
dramatic. 
4 DATA INTERPRETATION 
Data sets over both test area were 
interpreted visually. A series a schematic 
diagram has been drawn (Figures 2 and 3). 
4.1 The island of La Gonave 
The island of La Gonave can be described as 
an anticline oriented WNW-ESE (Butterlin, 
1960). Several domes (locally named "morne" 
are observed on the coregistered data set 
(Mercier de l'Epinay et al. 1985), they are 
(from NW to SE): 
the Morne Dandeville which affects some 
Miocene sandstones. It is well seen on 
the Seasat image because some stratas are 
perpendicularly oriented to the Seasat 
radar illumination direction, 
the domes of Plaisance and 
Morne-La-Pierre (Eocene of age) are 
observed on both Landsat MSS and Seasat 
data. An ambiguity exists in detecting 
the Morne-La-Pierre since its topography 
is not very well expressed, 
the dome of Pointe Fantasque is very well 
detected and may only be the southern end 
of the anticline. 
Three fault zones can be recognized: 
group 1: N65° to N70°. They are 10 to 
15 Km long and are well detected on the 
MSS images. Some faults oriented NW-SE 
delimit diamond shape areas where recent 
alluvial deposits can be found, 
group 2: subparallel to the anticline 
axis, they affect terrains Miocene of 
age. They are more numerous close to the 
center of the anticline. Their 
orientation indicates a gentle bending of 
the axis of the anticline, 
group 3: N80° to N95° which crosses all 
the structures previously described. 
The island of La Gonave may be interpreted 
as a broad folding structure related to the 
left lateral shear of South-Haiti as defined 
by Calmus, 1984. The signification of the 
domes of Dandeville, Plaisance and 
Morne-La-Pierre is still not explained and 
may be related to some evaporite extrusions 
(Mercier de l'Epinay et al. 1985). 
possible to locate major faults related to 
the left lateral shear of South-Haiti. 
Drainage pattern are detected on both data 
sets but distorsion are less important on the 
SIR-B data. Basaltic rocks are easier to 
locate on the Seasat SAR image. 
5 SUMMARY 
Synthetic Aperture Radar data obtained by 
Seasat in 1978 and by SIR-B in 1984 were 
compared over the Western part of Haiti. Two 
areas were studied : the island of La Gonave 
and the Miragoane area. Boundaries between 
rocks Eocene of age and rough basalts were 
precised as well as 1) domes, 2) ancients 
faults oriented NE-SW, 3) faults oriented 
NW-SE linked to the La Gonave anticline and 
4) faults oriented E-W integrated in the 
tectonic model of the Caribbean plate. 
REFERENCES 
Butterlin, J. 1960. Géologie générale et 
régionale de la République d'Haiti. Trav. 
et Mém. de l'Institut des Hautes Etudes 
d'Amérique Latine. Vol. VI, 194 p., 
Paris. 
Calmus T. 1984. Décrochement senestre 
Sud-Haitien: analyse et conséquences 
paléogéographiques dans la région de 
Camp-Perrin (Massif de Macaya, prequ'île du 
Sud d'Haiti). Ann. Soc. Géol. Nord, t C 
III, p.309-316. 
Ford, J.P., J. B. Cimino, B. Holt and M. 
R. Ruzek 1986. Shuttle imaging radar 
views the earth from Challenger: the SIR-B 
experiment. JPL publication 86-20. 
Mercier de l'Epinay, B., Ph. Rebillard, J. 
Chorowicz, P. Letouzey and J.M. Vila 
1985. Interprétation structurale de l'île 
de La Gonave (République d'Haiti) à partir 
d'images spatiales Landsat-MSS et Seasat 
SAR 1985. Géodynamique des Caraibes symp., 
p.363-369, Technip editon. 
Rebillard, Ph. and D. Evans 1983. Analysis 
of coregistered Landsat, Seasat and SIR-A 
images of varied terrain types. Geophys. 
Res. Letters 10-4, p.277-280. 
Vila, J.M., J. Butterlin, T. Calmus, B. 
Mercier de l'Epinay and B. Van Den Berghe 
1983. Atlas d'Haiti (Ch. Girault ed.), 
CEGET/CNRS Bordeaux. 
4.2 The Miragoane area 
The interpretation map of figure 4 was drawn 
using the map published by Vila and al., 
1983. 
Both Seasat SAR and SIR-B were acquired with 
almost the same radar illumination direction 
(therefore the layover is toward the West). 
The 20° incidence angle of Seasat, as 
mentionned earlier, induces foreshortening 
and foldover which impair greatly the 
interpretation. In mountaineous terrain, 
larger incidence angle such as the one of 
SIR-B over Haiti (60°), improves the 
interpretation ability. But on the other 
hand, the poor SIR-B signal to noise reatio 
did not enable to get a perfect radar image. 
Nevertheless, from both data set it is 
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