Calculo por SQL

DECLARE @v_polygon_string VARCHAR(1000)
DECLARE @g Geography
SET @v_polygon_string = 'POLYGON((
-70.106903276165 -20.253605204701,
-70.107765556612 -20.253818617830,
-70.107654186777 -20.254495614967,
-70.106938131964 -20.254400336391,
-70.106903276165 -20.253605204701
)) '
SET @g = Geography::STGeomFromText(@v_polygon_string, 4977)
SELECT @g.STArea()