English: A large volcanic crater known as a caldera is located at the summit of all of the Tharsis volcanoes. These calderas are produced by massive volcanic explosions and collapse.Today's VIS image shows the summit caldera of Arsia Mons. Several small volcanic vents are visible on the caldera floor. It is not uncommon for calderas to have "flat" floors after the final explosive eruption the empties the subsurface magma chamber. There may still be some magma or superheated rock left after the collapse that will fill in part of the depression. Additionally, over time erosion will work to level the topography. Within the Arsia Mons caldera there was renewed activity from several small vents that occurred along the alignment of the NE/SW trend of the three large volcanoes. This ongoing, low volume activity is similar to the lava lake in Kilauea in Hawaii. Arsia Mons is the southernmost of the Tharsis volcanoes. It is 450 km in diameter, almost 20 km high, and the summit caldera is 120 km wide. For comparison, the largest volcano on Earth is Mauna Loa. From its base on the sea floor, Mauna Loa measures only 6.3 miles high and 75 miles in diameter.The Arsia Mons summit caldera is larger than many volcanoes on Earth. Orbit Number: 79230 Latitude: -9.4441 Longitude: 239.984 Instrument: VIS Captured: 2019-10-25 02:43