Hotspot volcanoes

Extensive survey of over 1,800 “young” monogenetic volcanoes in the Southwestern United States

A view of the crater of Dotsero volcano, a monogenetic volcano that erupted in Colorado about 4,000 years ago. Credit: Greg Valentine

Study presents extensive investigation of monogenetic volcanoes less than 2.58 million years old in the southwestern United States.

They were born. They live once, erupting for a period that can last for days, years, or decades. Then they darken and die.

This story describes the life of a monogenetic volcano, a type of volcanic hazard that can pose significant dangers despite a fleeting existence.

The landscape of the southwestern United States is heavily marked by past eruptions from these volcanoes, and a new study marks a step toward understanding future risks to the region.

The research, to be published on November 2, 2021, in the journal Geosphere, provides a broad overview of what we know – and don’t know – about this type of volcanism in the Southwestern United States over the past 2.58 million years, a geological period known as Quaternary.

SP crater

SP Crater, a monogenetic volcano near the city of Flagstaff in Arizona. Credit: Greg Valentine

Meanwhile, more than 1,800 monogenetic volcanoes have erupted in the region, according to a tally covering Nevada, Utah, Arizona, Colorado, New Mexico and parts of the eastern edge of California. . Add the Pinacate Volcanic Field, located mostly in the Mexican state of Sonora on the Arizona border, and the number rises to over 2,200, scientists say. (The volcanoes included are those estimated to be of the Quaternary order, but many have not been precisely dated.)

“Monogenetic means ‘one life’,” says lead author Greg Valentine, a University of Buffalo volcanologist. “So a monogenetic volcano will erupt once, and that eruption can last from days to decades, but after that the volcano is practically dead.

Lunar lake

The peaks of monogenetic volcanoes, seen across Lunar Lake in Nevada. Credit: Greg Valentine

“In the United States, most of the volcanic hazard attention has rightly been directed to places like Hawaii, as well as the Pacific Northwest and Alaska, where we have large stratovolcanoes like Mount Rainier. and Mount St. Helens, which will experience numerous eruptive episodes over a long lifespan, with widespread dangerous effects. In the past, these small monogenetic volcanoes have not really been examined with a focus on the dangers; rather, they have been studied primarily for what they tell us about the deep earth. Recently, however, there has been more buzz in the research community about how we need to examine the types of dangers these volcanoes might pose.

“My experience with the general public is that most people are surprised to know that there are so many young volcanoes in the Southwest.”

The authors of the article are Valentine, PhD, professor of geology at UB College of Arts and Sciences; Michael H. Ort, PhD, professor emeritus of geology at Northern Arizona University; and Joaquín A. Cortés, PhD, Senior Lecturer in Geology at Edge Hill University in England.

These volcanoes will no longer erupt. So why study them?

The more than 2,000 volcanoes mentioned in the document have finished erupting, so they no longer pose a threat. But studying them is important because of the potential for new blooms.

“Monogenetic volcanoes tend to occur in areas we call volcanic fields, and the American Southwest is just dotted with them,” says Valentine, who grew up in New Mexico. “These are areas of high volcanic activity where future eruptions could occur, but we don’t know when and we don’t know exactly where.”

The city of Flagstaff, Arizona is located in a volcanic field where several monogenetic volcanoes have erupted in the past, so it’s important for people who live there to better understand the possible dangers.

Marcath cone

A view of Marcath Volcano, a monogenetic volcano in Nevada. Credit: Greg Valentine

“Two of the most recent eruptions in the southwest occurred near Flagstaff about 1,000 years ago, one just outside of town and the other on the north rim of the Grand Canyon,” Ort said. Northern Arizona University is located in Flagstaff. “The people who lived there at the time adapted to the effects of the eruptions, changing agricultural and cultural practices as well as where they lived. We will have to do the same when the next one breaks out. Albuquerque also has young volcanoes along its western margin.

Fortunately, most of the southwestern United States’ volcanoes are found in remote locations, far from major population centers. In isolated areas, threats of eruptions could include ash plumes that disrupt travel (including aerial) or electricity distribution infrastructure, the researchers said.

“One of the youngest eruptions in the Southwest occurred south of Grants, New Mexico a few thousand years ago, and spanned several miles parallel to what is now the Interstate 40 and is part of the Burlington Northern Santa Fe Railway, ”Ort said. “A similar eruption today would wipe out one of the country’s most important east-west transport routes. Several volcanic fields can be found along these roads, from the Mojave Desert in California to eastern New Mexico, including the one around Flagstaff.

“The basic information you need to start understanding the dangers and chances of a future eruption are the number of volcanoes, their age, and the types of eruptions they have,” says Valentine. “What we set out to do in the study is to find all the information we can about these monogenetic volcanoes in the southwestern United States and compile it in one place. How many are there? Their characteristics? We obtained information from state geological surveys, published articles and other sources.

What are the chances of another eruption within a century?

Based on the total number of volcanoes that erupted in the study region alone during the Quaternary period, the chances of a new volcano emerging in the region within 100 years would be around 8%, according to Valentine.

But he notes that this figure embodies a lot of uncertainty. This does not take into account buried volcanoes or the fact that a single eruption can create multiple vents. Further research will be needed to refine this estimate and predict the likely locations of a new eruption.

“There is so much uncertainty here, and that is part of the problem,” he says. “It’s sort of a very open field of research. When you look at the region from a volcanic hazard perspective, we really have very little information. Most volcanoes have not been dated, so we don’t know their age, except that they likely formed during the Quaternary Period. Very few have been studied in detail.

That said, the study results indicate that the frequency of eruptions in the study area may approach that of individual volcanoes in the Pacific Northwest, according to Valentine and Ort. The new document highlights knowledge gaps, and scientists hope it can serve as a launching pad for further, more detailed research. As Ort and Valentine point out, a new southwestern volcano could appear anywhere in any active volcanic field.

“We don’t have infinite resources, so we need to prioritize our efforts to anticipate and plan for hazards,” says Valentine. “But how do you set the priorities? If you monitor the volcanic fields of the Southwest, where do you place the instruments? Being able to better answer questions like these is where we are heading.

Reference: “Quaternary Basaltic Volcanic Fields of the American Southwest” by Greg A. Valentine, Michael H. Ort and Joaquín A. Cortés, November 2, 2021, Geosphere.
DOI: 10.1130 / GES02405.1