Volcanic mountains

Study: Emergency managers should plan for volcanic eruptions in the southwest


The southwestern United States has thousands of volcanoes that have only been active for a very short time, and a new analysis published in the journal Geosphere urges emergency managers to be aware of the potential for additional volcanic activity.

The study’s authors counted 2,229 volcanoes in 37 volcanic fields located in the southwestern United States and northern Mexico. Despite being dotted with volcanic fields, the region has not received the same attention for its volcanism as other parts of the country such as the Pacific Northwest, home to volcanoes like Mount Saint Helens and the Mount Rainier.

Greg Valentine, lead author of the article and professor of geology at the University of Buffalo, said one of the reasons the southwestern volcanoes haven’t received so much attention is that no eruptions has only happened since geology became an official science in the 1700s. During this time, the Cascade Range of the Pacific Northwest has seen modern explosions, such as Mount Saint Helens.

The type of volcanoes found in the Southwest are also different from those in the Pacific Northwest. As scientists monitor Mount Saint Helens and other volcanoes for activity that could signal another eruption, Valentine said future eruptions in the southwest are unlikely to originate from the same location, or from the same vent, where past eruptions occurred.

This makes monitoring for future breakouts a bit more difficult.

Valentine said that at Mount Saint Helens, scientists know that the next eruption will also occur on the mountain, although the exact location where the explosion will occur on the volcano is unknown. For this reason, they are able to place surveillance equipment around Mount Saint Helens.

“For this problem in the southwest, however, it’s a much more complicated problem because the area we’re talking about is obviously huge,” Valentine said.

He said the eruptions will likely occur in a volcanic field like those documented in the document, but those fields are quite large, making it difficult to determine the best place to place monitoring instruments. Earthquakes can be a harbinger of future volcanic activity and can be detected using instruments such as seismometers. However, if these instruments are located too far from the epicenter, they will not even be detected.

Valentine said the US Geological Survey and university researchers are working to find ways to prioritize areas for monitoring systems.

“We have a large number of volcanoes, they are small, they are monogenetic, they only live once. We know there will be more of these volcanoes in the future. So we should at least think about it from a dangers perspective, ”said Valentine.

A monogenetic volcano is a volcano that erupts once before dying out. These rashes can last a few hours or several decades. They also tend to form volcanic fields.

Valentine’s interest in southwestern volcanoes dates back to her childhood in northern New Mexico.

“As a child, I used to go for a walk in the mesas and I was really interested in the scenery and the rocks etc., and I found out later that it was volcanic,” he said.

Valentine has been researching southwestern volcanoes since the 1990s. He said over time it has become increasingly clear to him that these volcanoes represent a potential danger that people should think about.

Valentine partnered up with Michael Ort, a volcanologist who works at Northern Arizona University, and Joaquín Cortés, a volcanologist who works at Edge Hill University in England.

The last eruption in the southwest is estimated to have occurred less than a thousand years ago. Ort said there was a dispute over which is the most recent – Sunset Crater near Flagstaff, Arizona, or another volcano near the north rim of the Grand Canyon where people who lived in the area at the time placed shards of pottery in the lava. He said these eruptions occurred between 1050 and 1200 AD. Many volcanoes in the southwest have not been studied enough to determine their age, Valentine said. Of the more than 2,000 volcanoes in the region, only about 25% have been dated.

Ort said there is a very low chance – around 8% – that an eruption will occur in any given year in one of the region’s many volcanic fields. He said the possibility of an eruption is not something people should stress, but emergency officials, such as government officials, should be aware of the possibility and should plan for such events.

Ort said people will likely be able to escape future eruptions and he sees them as more likely to impact infrastructure than to be fatal.

However, if the lava were to interact with groundwater, it could become very explosive and dangerous.

Valentine and Ort both talked about these volcanoes, known as Maars, which, rather than forming a cone or peak, leave huge craters behind.

“The rising magma, the molten rock, interacts with the groundwater in a certain way that causes very violent explosions,” said Valentine.

He said it can be seen in the Potrillo field in southern New Mexico and parts of Mexico.

The Potrillo Field is one of the state’s many volcanic fields, Ort said. Due to its size, the authors devoted part of the article to it. There are approximately 124 vents in the Potrillo Volcanic Field. Kilbourne Hole and Hunts Hole in the Potrillo Field are examples of Maar volcanoes.

Kilbourne Hole, located in the Desert Peaks-Organ Mountains National Monument, is over a mile wide and over 300 feet deep.

Regardless of the blast from the eruption, Ort said volcanic activity would impact neighboring communities. For example, ash thrown into the air can impact areas hundreds of kilometers away.

Although the Potrillo Volcanic Field is one of the largest volcanic fields in the state, it has not seen the most recent eruptions. Ort said New Mexico’s youngest volcanoes are near White Sands and Grants, and there are also volcanoes near Taos.

Ort and Valentine plan to further study the volcanoes in the southwest.

Ort said they wanted to know more about how eruptions changed over time and how long they lasted. He said this research could use stratigraphic techniques, such as examining erosion patterns.

While scientists don’t know how often these eruptions occur, Ort said it had been over 900 years since the last one in the southwest and the next eruption is likely to occur as long as humans live in the area.

Valentine said the eruptions could send plumes of gas up to 30,000 feet into the air, which would impact air traffic.

“When the ashes disperse into the atmosphere in one of these plumes, they blow downwind and settle on the landscape and can interfere with power transmission lines to interfere with transportation on highways, roadways. iron. So this kind of rash can actually be quite disruptive, ”he said.

Ort and Valentine both said people don’t need to be afraid of the future of eruptions, but planning is necessary.

“There is a real possibility that one of these monogenetic eruptions will occur within the next 100 years or so,” Valentine said. “It’s not something we have to worry about or fear, but we can plan it. And we can work on ways to improve our preparation. Also in terms of tracking and one of the things to remember is that this is really a huge open field of research. It is a significant danger. But it requires a lot more study.