Arizona's Volcanic Fields ... home to thousands of young volcanoes

San Francisco volcanic field (I think), Northern Arizona

HERE  … The youngest, Sunset Crater, erupted around A.D. 1085. That eruption forced Native Americans to relocate to what is now National Monument.

While there are no active volcanoes in Arizona, there are volcanic fields capable of producing new volcanic activity:

Geologically speaking, Arizona is home to thousands of young volcanoes.

The San Francisco and volcanic fields in northern Arizona, and the volcanic field on the Arizona-Mexico frontier. In this map HERE  each colored area represents one of these fields. Hover over a color and click on it view a slide show and to learn more about each field. Zoom in and pan around to get a bird’s eye view of the fields.

HERE Why does Northern Arizona have so many geologically young volcanoes? Most volcanoes are located near boundaries of the Earth’s tectonic plates, but Arizona is well within the interior of the North American Plate. Some geologists suggest that there is a site of localized melting, or “hot spot,” fixed deep within the Earth’s mantle beneath northern Arizona. As the North American Plate moves slowly westward over this stationary source of molten rock (magma), eruptions produce volcanoes that are strung out progressively eastward.

The first volcanoes in the San Francisco Volcanic Field began to erupt about 6 million years ago, in an area where the town of Williams is now. Subsequently, a several-mile-wide belt of successively younger eruptions migrated eastward, to the area of modern Flagstaff, and even a bit beyond, toward the valley of the Little Colorado River. Today, this belt of volcanoes extends about 50 miles from west to east.

Although there has been no eruption for nearly 1,000 years, it is likely that eruptions will occur again in the San Francisco Volcanic Field. With an average interval of several thousand years between past periods of volcanic activity, it is impossible to forecast when the next eruption will occur. U.S. Geological Survey (USGS) scientists believe that the most probable sites of future eruptions are in the eastern part of the field and that the eruptions are likely to be small. These future eruptions may provide spectacular volcanic displays but should pose little hazard because of their small size and the relative remoteness of the area.