San Francisco volcanic field
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The San Francisco volcanic field is an area of volcanoes in northern Arizona, USA. The field covers 1800 square miles (4700 km2) the southern boundary of the Colorado Plateau. The field contains 600 volcanoes ranging in age from less than 6 million years old to less than 1000 years, of which Sunset Crater is the youngest. The highest peak in the field is Humphreys Peak which is Arizona's highest peak at 12,633 feet (3850 m). Humphreys Peak is a part of the San Francisco Peaks an extinct stratovolcano complex near Flagstaff, Arizona.
The volcanic field seems to have formed from a geological hotspot, a hot area in the mantle. As the North American plate moves over the spot, new volcanoes appear. Thus, the newest volcanoes are at the east side of the field. Most of the volcanoes are basalt cinder cones, but there are also large lava domes consisting of rhyolite and dacite.
Given that Sunset Crater is such a young volcanic feature of this area and that eruptions have occurred every several thousands of years in frequency, it is likely that there will be a future eruption in the San Francisco Volcanic field. However, it is impossible to predict when and exactly where a new eruption might occur. The USGS (United States Geological Survey) does say that a future eruption would most likely be in the eastern side of the volcanic field, where the most recent volcanic activity has occurred. Such an eruption is likely to be small and pose little or no hazard due to the remoteness of the area.
The volcanic field is not near San Francisco, California and should not be confused with that city.
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