Unraveling active magma by drilling in the heart of volcanoes

Volcanic eruptions, while undeniably fascinating, are relatively infrequent occurrences when compared to the dormancy that most volcanoes experience. Understanding the characteristics and behaviors of magma prior to an eruption is critical for effective volcanic activity forecasting.

A groundbreaking study led by LMU volcanologist Dr. Janine Birnbaum has for the first time reconstructed the conditions present within a magma chamber, offering insights into the response of magma to drilling activities. These significant findings have been published in the journal Nature and have the potential to advance magma monitoring techniques while introducing new applications.

Magma traverses from deep within the Earth's interior towards the surface, frequently halting within the crust for extended periods ranging from years to millennia. During this time, it undergoes cooling, crystallization, assimilation of surrounding crustal material, and alterations in its dissolved gas content, particularly in water and carbon dioxide—key components that drive volcanic eruptions.

An eruption is triggered when a disturbance affects the magma system, such as an increase in heat, the introduction of additional magma from below, or gas bubble formation—akin to an over-pressurized soda can that ultimately bursts.

Drilling in Krafla volcanic field in Iceland

To gain a deeper understanding of volcanic behavior in the intervals leading up to eruptions, it is essential to acquire precise data regarding the temperature, pressure, and gas composition of magma located within the Earth's crust. However, the inaccessibility of magma at such depths presents challenges for direct measurement.

In their recent study, the researchers capitalized on the advantageous proximity of magma beneath the Krafla volcanic field in northeastern Iceland to the surface. In a serendipitous event during the 2009 operations at the Krafla Geothermal Station, the Iceland Deep Drilling Project 1 (IDDP-1) well unexpectedly intersected a magma body at just over 2 kilometers deep. The introduction of cold drilling fluids resulted in the rapid cooling of the magma, transforming it into small fragments of glass.

Upon examination of these glass fragments, researchers faced an intriguing anomaly: despite the presence of numerous small bubbles, the quenched magma exhibited a gas content that was lower than what was expected under the observed temperature and pressure conditions. To unravel this phenomenon, LMU researchers employed a novel numerical model, indicating that the magma lost gas during the drilling process prior to achieving full solidification into glass.

Prior measurements indicated that the magma's cooling duration from approximately 900 °C to a glass state around 520 °C spans several minutes. The researchers hypothesized that this timeframe permitted gas to escape from the melt, subsequently causing the formation of visible bubbles.

Gas escapes within five minutes

Thus, the gas content in the glass chips does not indicate the initial conditions but instead reflects the effects of this dynamic process. "It's like a blurry photo," notes Birnbaum.

"However, if we account for our exposure duration and the velocity of our system, we can determine its original starting point." By simulating the rate of gas escape, the researchers reconstructed the initial gas content, which revealed that the "missing" gas was expelled within five minutes of the drilling operation.

These findings hold promise for enhancing safety in future geothermal exploration efforts on active volcanoes, while also offering avenues for targeted magma drilling aimed at monitoring activities and facilitating green energy extraction.

Publication details
Janine Birnbaum et al, Disequilibrium response to tapping crustal magma reveals storage conditions, Nature (2026). DOI: 10.1038/s41586-026-10317-w

Journal information: Nature

Key concepts: magma, geothermal resources, volcanic activity, volcanic eruption prediction