Rio Grande Rise

The Rio Grande Rise is an aseismic ridge located in the South Atlantic Ocean. Aseismic ridges are long, mountainous underwater structures that are distinct from oceanic spreading centers because they do not experience earthquakes. These ridges are typically formed by volcanism from a hot spot, creating a series of volcanoes. The Rio Grande Rise, along with the Walvis Ridge, is believed to have originated from a hot spot near the Mid-Atlantic Ridge during the initial opening of the South Atlantic Ocean between 100 and 80 million years ago. Drilling samples indicate that the Rio Grande Rise was once a volcanic island approximately one mile high.1