Moving Mountains

The Earth is truly an amazing planet which we are privileged to live upon for a brief instant of Time.

Scientists from the Swiss Seismological Service at ETH Zurich have been measuring the movement in one of the world’s most iconic mountains – The Matterhorn.

The measuring station on the Matterhorn summit. Image credit: Photo: Jan Beutel / ETH Zurich

Scientist Donat Fäh explains:

“The movements of the underground cause every object to vibrate, which we fortunately cannot feel, but detect with sensitive measuring instruments.”

These so-called natural frequencies depend primarily on the geometry of the object and its material properties. The phenomenon is also observed in bridges, high-rise buildings, and now even mountains.

Samuel Weber, who carried out the study during a postdoctoral period at the Technical University of Munich (TUM) and is now working at the WSL Institute for Snow and Avalanche Research SLF, said:

“We wanted to know whether such resonant vibrations can also be detected on a large mountain like the Matterhorn.” 

He emphasizes that the interdisciplinary collaboration between researchers at the Swiss Seismological Service at ETH Zurich, the Institute for Computer Engineering and Communication Networks at ETH Zurich, and the Geohazards Research Group at the University of Utah (USA) was particularly important for success of this project.

Seismometers recorded all movements of the mountain at high resolution, from which the team could derive the frequency and direction of resonance. The measurements show that the Matterhorn oscillates roughly in a north-south direction at a frequency of 0.42 Hertz, and in an east-west direction at a second, similar frequency. In turn, by speeding up these ambient vibration measurements 80 times, the team was able to make the vibration landscape of the Matterhorn audible to the human ear, translating the resonant frequencies into audible tones.

Researchers from the Swiss Seismological Service carried out a similar experiment on the Grosse Mythen as part of the study. This peak in Central Switzerland has a similar shape to the Matterhorn, but is significantly smaller. As expected, the Grosse Mythen vibrates at a frequency around 4 times higher than the Matterhorn, because smaller objects generally vibrate at higher frequencies.

Scientists from the University of Utah were then able to simulate resonance of the Matterhorn and Grosse Mythen on the computer making these resonant vibrations visible. Previously, the US scientists have mainly examined smaller objects, such as rock arches in Arches National Park, Utah.

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