The Olympus volcano on Mars: Geometry and characteristics of lava flows

The HRSC (image 0037) and MOC imagery and MOLA altimetry were used to determine the following parameters of the lava flows typical of the southern slope of the Martian volcano Olympus: the length (13-35 km), the width (0.2-4.8 km), and the angles of ground slopes along which these flows advanced (3.4 degrees-6.9 degrees). To measure the thickness of the flows, we applied a method which had never been used before for Mars. In this method, the apparent thickness obtained from the MOC images and the slope steepness obtained from the MOLA data are used to determine the true thickness. The average estimates of the thickness of lava flows vary from 4 to 11 m and from 4 to 26 in for the volcano flanks and caldera. scarps, respectively. These values are close to those of terrestrial basalt flows and to the lower limit found for the Martian flows by other researchers. Based on the performed measurements, we estimated the lava yield strength (0.9 x 10(3) -3.6 x 10(4) Pa), the supply rate (24-137 m(3)/s), and the viscosity (1.4 x 10(3)-2.8 x 10(7) kg/m s). These values are close to the estimates found for the Martian lavas by other researchers and to the characteristic values of these parameters for terrestrial lava flows with basalt and basalt-andesite composition.