See you soon! Can huge mountain peaks resonate? yes! It's the "Matterhorn."

The Matterhorn looks like a huge, immovable mountain that has towered over the landscape near Zermatt for thousands of years. Now a study suggests that this impression is wrong. An international team of researchers has shown that the Matterhorn is not static, but is constantly in motion, gently rocking back and forth about every two seconds. This subtle vibration, which is often imperceptible, is driven by seismic energy from the world's oceans, earthquakes, and human activity on Earth.

Each object vibrates at a certain frequency when stimulated, such as a tuning fork or guitar strings. These so-called natural frequencies depend mainly on the geometry of the object and its material properties. This phenomenon can also be observed in bridges, high-rise buildings, and even on today's mountain peaks.

Samuel Weber said: "We wanted to know if this resonant vibration could also be detected on a mountain like the Matterhorn. He conducted the study during his postdoctoral stay as a professor of landslide research at the Technical University of Munich (TUM) and is now working at the WSL Avalanche Institute SLF. He stressed that the interdisciplinary collaboration between researchers from the Swiss Seismological Office at ETH Zurich, the Institute for Computer Engineering and Communication Networks at ETH Zurich, and the Geological Hazard Research Group at the University of Utah (USA) was particularly important to the success of the project.

To make the study a reality, the scientists installed several seismometers on the Matterhorn, one directly on the summit of the mountain at an altitude of 4470 meters, and the other on Solvay bivouac, an emergency shelter on a northeastern ridge, better known as Hörnligrat. Another measuring station at the foot of the mountain is used as a reference. Jan Beutel (ETH Zurich/University of Innsbruck) and Samuel Weber's extensive experience in installing equipment to measure rock motion on high mountains in the past has made the deployment of measurement networks possible. This data is automatically transmitted to the Swiss Seismological Office.

The seismometer recorded all the movements of the mountain in high resolution, from which the team could derive the frequency and direction of resonance. The measurements show that the Matterhorn oscillates roughly in the north-south direction at a frequency of 0.42 Hz, while in the east-west direction oscillates at a second similar frequency (see animation). In turn, by increasing the speed of these environmental vibration measurements by a factor of 80, the team was able to make the human ear hear the vibrational landscape of the Matterhorn, converting the resonant frequency into audible tones.

Amplified vibrations on the top of the mountain

Compared to the reference station at the foot of the Matterhorn, the intensity of exercise measured at the summit is up to 14 times. For most of the team's data, these movements are small, typically in the nanometer to micron range. The increase in ground movement with height can be interpreted as the peak moves freely while the foot of the mountain is fixed, equivalent to a tree swaying in the wind. This amplification of ground motion on the Matterhorn can also be measured during an earthquake, and the team notes that this amplification may have an important impact on slope stability in the event of a strong earthquake. Jeff Moore of the University of Utah, who initiated the Matterhorn study, explains. "Areas of mountains that have undergone amplified ground movement may be more susceptible to landslides, rockfalls and rock damage when shaken by strong tremors."

This vibration is not unique to the Matterhorn, and the team notes that many mountain ranges vibrate in a similar way. As part of the study, researchers at Swiss Seismological Agency conducted a supplementary experiment in Grosse Mythen. This mountain in central Switzerland is similar in shape to the Matterhorn, but significantly smaller. As expected, Grosse Mythen vibrates at about four times higher frequencies than the Matterhorn, as smaller objects typically vibrate at higher frequencies. Scientists from the University of Utah were then able to simulate the resonances of Matterhorn and GrossMayten on a computer, making these resonance vibrations clearly visible. Prior to that, American scientists had mainly studied smaller objects, such as the Rock Arches in Arches National Park in Utah. Jeff Moore said: "It is exciting to see that our simulation method is also valid for mountains like the Matterhorn, and the results are confirmed by the measurement data." "