While it may be surprising to hear, Arizona is home to seven young volcanic fields. Three fields, the San Francisco, Uinkaret, and Pinacate, are active (meaning they’ve erupted in around the past 12,000 years or have the potential to erupt again in the future). Aidin Robbins visited one of these fields, checking out the confusing nature of Arizona’s volcanoes.
Volcanoes typically devlope near tectonic plate boundaries, but the closest one to Arizona is the San Andres Fault in California more than 400 miles away. And yet hundreds volcanoes can be found throughout the state.
Most volcanoes in the specific field Robbins visits are cinder cones. These were formed by short and explosive eruptions that created symmetrical mounds. Why exactly the volcanoes formed where they did is a question asked by many scientists.
Currently the leading beliefs are that either crustal rifting, where the earth’s crust stretches thin, or an unmoving hotspot in the Earth’s mantle led to the creation of these volcanoes. Hotspots on land aren’t very common but they are possible. Yellowstone, for example, is a hotspot.
Plenty of questions still remain surrounding Arizona’s volcanic fields. If it’s a hotspot, why hasn’t it formed large volcanoes at a few prominent vents like they usually do? Why are there hundreds of small cinder cones? When will the next eruption occur?