Crater Isabella, the second largest impact crafter on Venus with a diameter of 108 miles (175 kilometers), as seen by the Magellan spacecraft's radar. he feature is named in honor of the 15th Century queen of Spain, Isabella of Castile.
Located at 30 degrees south latitude, 204 degrees east longitude, the crater has two extensive flow-like structures extending to the south and to the southeast. The end of the southern flow partially surrounds a pre-existing 25 mile (40 kilometer) circular volcanic shield.
The southeastern flow shows a complex pattern of channels and flow lobes, and is overlain at its southeastern tip by deposits from a later 12 mile (20 kilometer) diameter impact crater, Cohn (for Carola Cohn, Australian artist, 1892-1964).
The extensive flows, unique to Venusian impact craters, are a continuing subject of study for a number of planetary scientists. It is thought that the flows may consist of 'impact melt,' rock melted by the intense heat released in the impact explosion.
An alternate hypothesis invokes 'debris flows,' which may consist of clouds of hot gases and both melted and solid rock fragments that race across the landscape during the impact event. That type of emplacement process is similar to that which occurs in violent eruptions on Earth, such as the 1991 Mount Pinatubo eruption in the Philippines.