This is a Magellan radar mosaic of the Navka region of Venus. The mosaic is centered at 15 degrees north latitude and 352 degrees longitude and covers a region 1840 kilometers (1100 miles) east-west and 1600 kilometers (970 miles) north-south. The north-south black bars are regions of missing data. The southern halves of two large volcanoes are located at the top of the image. Sif Mons, at the top-center, is approximately 500 kilometers (300 miles) across and rises about 2.5 kilometers (1.5 miles) above the average elevation of the planet's surface. The 30 kilometer (18 mile) circular region (called a caldera) is the probable source of the many lobate lava flows that radiate downhill. A ten kilometer (6 mile) diameter impact crater surrounded by a dark halo is located on the slopes of the volcano 225 kilometers (135 miles) southwest of the central caldera. To the east of Sif is Gula Mons, a 550 kilometer (330 mile) diameter volcano that is 3.5 kilometers (2.1 miles) high. The summit of Gula Mons is composed of 2 calderas joined by a belt of linear deformation. The southwestern of these 2 calderas is the bright circular region in the upper right of the image. As at Sif Mons, bright and dark flows radiate downhill from the volcano. The concentrated region of bright lines southeast of Gula is the near end of a rift zone that intersects Gula at the caldera. Many other bright linear features cross the mottled plains that surround the volcanoes. In the center of the image is a 40 kilometer (24 mile) diameter impact crater. The bright halo surrounding the crater may be a fairly thin deposit, since the fractures on the underlying plains can still be seen. These plains are probably volcanic in origin; the boundaries between different areas of plains often have a flow-like morphology. There is another smaller volcano in the lower left of the image, emphasizing that this region of Venus has been very active volcanically.
