Scientists study Socorro magma body to improve volcanic understanding

Although volcanoes have been widely studied, unraveling the mysteries of underlying magma transport proves to be a difficult quest. Grant Block, a graduate student in the Department of Physics and Astronomy at the University of New Mexico, recently conducted an extensive study of the Socorro Magma Body (SMB) in Socorro, New Mexico, which provides a window into the magmatic processes important in volcanic activity (although there is no such activity above MSY).

Block, with his Ph.D. Advisor Professor Mousumi Roy collaborated with the University of Alaska Fairbanks to deepen the understanding of SMEs. The research titled “Pressurizing Magma Within Heterogeneous Crust: A Case Study at the Socorro Magma Body, New Mexico, US” was recently published in the journal Geophysical research letters.

This paper models how crustal magma is stored in magma bodies (regions that are mostly liquid magma) and “mushes” (mostly solid crystals and some liquid magma). The mush areas are thought to be too viscous to erupt, but are likely weaker than the surrounding rock.

The goal of this project was to try to better understand the mechanisms behind the pattern of central uplift and peripheral subsidence, called “sombrero deformation,” observed at the surface above the SMB. The SMB is a mid-crustal magma body with no magma transport or volcanism above, making it a perfect “laboratory” for studying the dynamics of mid-crustal magma bodies in general.

“Deepening our knowledge of mid-crustal magma bodies will help us better understand the complete magma transport systems of the crust where they are located. It is these systems that power every volcanic eruption on Earth, so their study is crucial” , Block said.

More specifically, Block and his team were interested in the role of “mush” in these systems. Slush is magma that has crystallized to the point where it is too viscous to erupt, but is even more deformable than the surrounding rock. It is believed to play an important role in the dynamics and evolution of magma reservoirs such as the SMB.

Surface deformation at the Socorro Magma Body (SMB) was used in this project to study magma-mush interaction. Previous surface deformation measurements at the SMB show long-lasting “sombrero” deformation.

“Our goal for this project was to use surface deformation measurements above the SMB to better understand the role of mush in the SMB. This could enrich geoscientists’ understanding of crustal magma transport systems as a whole ” Block said.

Block’s research was computational, meaning he developed computer simulations of a simplified SMB system that he ran at UNM’s Center for Research Computing (CARC). The development of these simulations was based on satellite radar data analyzed by collaborators at the University of Alaska Fairbanks. Block was able to show that his simulations agreed well with the pattern of surface movements observed from radar data analyzed by the University of Alaska Fairbanks.

“This agreement allows us to use parameters from my models, such as the geometry and viscosity of a mushy or otherwise conformal region around the SMB, to make predictions about real SMB systems (which is very difficult to observe directly).These parameters we found could be tested further in future studies,” Block said.

The new satellite radar measurements are consistent with the previously reported pattern, confirming that this deformation has remained remarkably constant for almost 100 years. Block and Roy suggest that this is due to a large, weak, conformal region surrounding the SMB, which could be mush.

Their computer models reproduce a durable and consistent pattern of sombrero deformation, dependent on the properties of the mush as well as the pressurization of the magma body, and the authors suggest that these factors could explain why this pattern is relatively rare.

The scientists were able to see that their simulations were able to have good agreement with the data when they had a conformal region of lower viscosity than the background structure surrounding a periodically and asymmetrically pressurized SMB source. This docile region could be reduced to nothing or otherwise weakened. This question will be the subject of future work.

“No one in New Mexico is in imminent danger of volcanic unrest from WNS or anything else in the state. However, right beneath our feet is an ideal testing ground that will help scientists to understand volcanoes around the world. And beyond the SMB, there is so much to do. New Mexico’s rich natural landscape and history have been shaped by magmatic activity, from Valles Caldera to El Malpais via Bandelier.

“We live in a state shaped by volcanoes and our state can now play a major role in understanding and protecting people from volcanoes. This is something every New Mexican can be proud of,” Block said.

The researchers were able to conclude that a conformal (potentially mushy) region surrounding an asymmetric pressure source is a reasonable approximation for the mechanics of the SMB, verified with ground surface velocity data.