Important breakthroughs were made not only in understanding how magma moves in general, but how it works specifically at Oldoinyo Lengai. This spectacular volcano, located in northern Tanzania, is the world’s only active carbonatite volcano. Miriam Reiss, a volcano seismologist at Johannes Gutenberg University Mainz (JGU), heads a committed group of researchers. For the last 18 months, they have been continuously recording and analyzing seismic earthquake data. Their research exposes the secret recipe behind the bizarre magma makeup of the volcano. This magma exhibits the most extreme compositional deviations from classic magmas.
Oldoinyo Lengai is an unusual and curious volcano in many respects, attracting volcanologists and visitors from around the globe. In general, it is the extraordinary fluidity and high temperature of its magma that differentiate it from the other volcanoes. Here, the fast-moving magma is at a cool 550 degrees Celsius. Common magmas tend to be much cooler, often between 650 and 1,200 degrees Celsius. This unusual feature could be key to how magma and gas move through the Earth’s crust.
Seismic Data Analysis and Findings
The research team zeroed in on a nine-week period in the larger 18-month dataset gathered at Oldoinyo Lengai for additional analysis. They found two different types of tremor related to the movement of magma underneath the volcano. One of them had come from a depth of at least five kilometers. The second type was recorded around the foot of the volcano.
“For the first time, we were able to determine the precise location where tremor occurs,” – Reiss.
The pattern of these tremors indicates a connected network more than 10 kilometers (6.2 miles) under the surface of Oldoinyo Lengai. Reiss explains further, “We discovered that two types of tremor seem to be linked: One originated at around five kilometers depth and the other near the base of the volcano—with a time delay between them. It’s no mystery that these signals are related, so what we have is a highly direct, tightly linked system here.
The results offer new understanding into how subsurface magma movement can generate volcanic tremors and drive volcanic eruptions. As Reiss explains, tremor events are a sign that magma is on the move, and these are frequently harbingers of volcanic eruptions themselves.
Implications for Volcano Seismology
This unprecedented study significantly pushes the frontier of volcano seismology. It goes a long way toward improving our ability to forecast future eruptions. The researchers believe that understanding which tremor signals indicate an imminent eruption versus those that are merely background noise is crucial for future predictions.
“But which tremor signals are true precursors of an eruption, and which are just background ‘gurgling’? Our results lay the foundation for improving eruption forecasting in the future,” – Reiss.
Specifically, Reiss highlights the value of understanding these signals and wave types that are created by magma movement beneath the surface. To her, that’s the most exciting part—studying the many signals and wave types that result when magma moves under the surface. It’s a side of volcano seismology that absolutely enchants her.
Furthermore, the study has a profound effect on the scientific community and human lives in terms of public safety. By improving eruption forecasting, it can dramatically lower the risks associated with volcanic eruptions.
Unique Characteristics of Oldoinyo Lengai
Oldoinyo Lengai’s continued existence as the only active carbonatite volcano on the planet makes it truly unique amongst its volcanic peers worldwide. Unlike silicate volcanism, which predominates in most of the world’s active volcanoes, carbonatite volcanism includes explosive and effusive eruptions of magma high in carbonate minerals. This special make-up is part of what gives it its cooler temps and more flowy consistency.
The research team’s recent findings reinforce Oldoinyo Lengai’s role as a natural laboratory for studying volcanic processes. Learning more about its special magma-making properties is a key to unlocking potentially life-saving knowledge about volcanic activity around the world.