New Mexico is home to many hundreds of volcanoes that erupted during the last several million years. However, the exact timing of these eruptions has proven difficult to determine by many previous studies. An ongoing NSF-funded project, led by NM Bureau of Geology researcher Matthew Zimmerer, examines the timing of eruptions during the last 500,000 years in order to understand the patterns of volcanism in space and time. This information provides the foundation for an assessment of volcanic hazards in New Mexico.
The new geochronology indicates a more active volcanic history than previously recognized and is identifying new patterns of volcanism. The eruption frequency during the last 100,000 years is approximately one eruption per 3,700 years, which is slightly higher than the long-term average eruption frequency of one per 7,800 years during the last 500,000 years. Another exciting discovery is that the locations of volcanic vents within individual volcanic fields are migrating from the west to the east-northeast at a rate of 2-5 cm/year and is possibly related to the southwestern movement of the North America plate over a relatively stable source of magma generation. A component of this study, published in the Journal of Volcanology and Geothermal Research in January 2016, showed that the youngest eruption at Valles Caldera occurred at about 68,300 years ago, ending a nearly 30-year-quest by scientists to determine the last pulse of activity at the New Mexico’s dormant supervolcano. This work may lead to new initiatives to understand the history and hazards of volcanism throughout the southwestern United States.