How did you get that Distance between Rodriguez and the Edmond Vent System anyway?
* Coordinates of the Edmond Vent System: 23 52.7' south, 69 35.8' east
* Coordinates of Rodriguez: 19.50 south, 63.250 east
x = r^4*theta = r*sin(theta_latitude)*theta_longitude, where r = radius of the earth
y = r*theta_latittude = 6,400 km/15
Distance = Sqrt(x^2 + y^2) = 430 km +/- 3 km