Field tests of a unique compact laser inclinometer were conducted in Kamchatka over the course of a year. The device measures tilts of the Earth’s surface with precision down to billionths of a degree. The new instrument has already demonstrated outstanding results: it detects not only earthquakes, but also microscopic deformations caused by tides, storms, and even passing trucks. This opens the way to more accurate forecasting of seismic and volcanic activity.

How the Laser Inclinometer Works

The principle is simple but ingenious. A laser beam is reflected from a thin layer of liquid inside a cuvette. When the surface tilts even slightly, the reflected beam shifts, and ultra-sensitive sensors detect this movement. The liquid damps its own oscillations through friction with the bottom, eliminating interference from wind or vibrations.

The inclinometer operates across an exceptionally wide frequency range, from 0.00001 to 20 Hz. This allows it to capture ultra-low-frequency signals that conventional seismographs simply cannot detect.

The instrument was installed in a seismic chamber of the Kamchatka Branch of the Unified Geophysical Service of the Russian Academy of Sciences and the Institute of Volcanology and Seismology of the Far Eastern Branch of the RAS. Observations were carried out from December 2022 to December 2023, exactly one year.

What Was Recorded Over the Year

The results are impressive. Over 12 months, the surface tilted by about 20 microradians. Scientists observed recurring oscillations with periods of 5 to 10 days and amplitudes of around 10 microradians, which are likely linked to volcanic activity.

“During the observation period, the Earth’s surface tilted by approximately 20 microradians. We saw repeated changes with intervals of 5 to 10 days and amplitudes of about 10 microradians. Such oscillations may be associated with volcanic activity,” said Rodoslav Izrapil, head of the information center of the Joint Institute for Nuclear Research at Vitus Bering Kamchatka State University.

The sensitivity proved to be extraordinary. The device detected solid Earth tides, deformations of the crust caused by the gravitational pull of the Moon and the Sun, microseisms from ocean storms, where standing waves press on the seabed and transmit vibrations to land, and even vibrations from passing delivery vans.

Signals from volcanoes are especially valuable. As pressure builds up inside a volcano, its slopes rise, and the inclinometer records tilts as small as 50 nanoradians. This is considered a precursor to an eruption.

Future Prospects: A Network Across Kamchatka

Scientists propose creating a network of such inclinometers across the entire peninsula. Using two devices placed close together would further increase accuracy, as comparing their data would help eliminate noise. In the long term, this approach could help forecast not only eruptions, but also zones where seismic energy accumulates before earthquakes.

In Brief

A laser inclinometer capable of detecting Earth surface tilts with precision down to billionths of a degree was tested in Kamchatka for a year. It recorded tides, storms, volcanic activity, and even passing trucks. This represents a major breakthrough for forecasting earthquakes and eruptions. Scientists plan to deploy a network of these instruments across the region. Kamchatka is becoming a testing ground for a new era in seismology.