PDF file - Laboratoire de Géologie de l'Ecole normale supérieure - Ens

VIGNY ET AL.: ARABIA PLATE MOTION
Figure 3. Arabian sites velocities in the ITRF2000 reference frame, relative to Arabia defined in this work. Black
arrows depict our solution, white arrows are for McClusky et al. [2000]. For our solution, ellipses show the 99%
confidence level of the velocity uncertainties given in table 2. Numbers next to arrow heads indicate the station
velocity in mm/yr.
clearly outside the deforming zone: CBL0, LLL0 and
GOR0 [Vigny et al., submitted, 2004]. Inversion of the
velocities at these 6 sites leads to an angular velocity
vector (47.69°N, 98.32°W, 0,330°/Myr). In spite of a
poor fit at SEY1 (4 mm/yr), the RMS residual on the 6
velocities is 0.8 mm/yr (Figure 5). We checked the
stability of our solution in the same way as for Africa.
The unweighted inversion leads to nearly the same
8
angular velocity vector (only the latitude differs by
0.04°) but removing SEY1, for which the time series
shows numerous gaps, slightly changes the solution
(48.12°N, 97.75°W, 0.329°/Myr) (Table 3). Our
solution for Somalia thus significantly differs from
previous ones because it uses constraints in the northern
part of the plate (sites CBL0, LLL0 and GOR0). Sella et
al.’s [2002] and Fernandes et al.’s [2003] models show