OASIS

Aiming to demonstrate the potential of atmospheric measurements to provide early warnings for tsunamis, the OASIS project — Observations of Airglow with Spectrometer and Imager Systems — is hosted at ESO’s Paranal Observatory in Chile.

Tsunamis are giant waves caused by earthquakes under the sea. These earthquakes generate sound waves that travel upwards through the atmosphere. Due to atmospheric density decreasing with altitude, these perturbations that are initially small and undetectable at their origin become significant in the upper atmosphere. There, these perturbations affect the so-called airglow or nightglow –– light emitted naturally by certain molecules excited by the sunlight. Observing this airglow can therefore be used to detect these earthquakes shortly after they occur, providing a potential early warning system for the tsunamis they can generate.

OASIS comprises a container with a spectrometer, GRIPS 19 (Ground-based Infrared P-branch Spectrometer), and two cameras, FAIM 6 and FAIM 7 (Fast Airglow IMager), alongside their associated equipment. These instruments will study the airglow coming from hydroxyl molecules (OH). The cameras will map the spatial distribution of the airglow in the sky, whereas the spectrometer will measure how the OH molecules rotate. All instruments will take measurements every few seconds, every night from dusk until dawn.

This project is the result of a collaboration between ESO and the German Aerospace Center (DLR). OASIS is operated by DLR and hosted by ESO at Paranal. The project’s first test observations were conducted in November 2022, with OASIS being officially inaugurated in April 2024.

Science with OASIS

The primary goal of OASIS is to detect and characterise earthquakes happening on the seafloor, which may cause tsunamis, by monitoring airglow at around 86-km altitude. Chile is close to two tectonic plate borders that frequently cause earthquakes, including some that may rarely result in tsunamis –– a hazard that can cause catastrophic loss of life and damage to infrastructure. These earthquakes produce sound waves, and OASIS aims to measured the effects of these waves to detect and characterise them, and trace them back to their source. Since sound waves reach these atmospheric altitudes in as little as 7 to 9 minutes after being produced, the data could eventually be used to provide early warnings for incoming tsunamis to civilians and mitigate destructive effects. The OASIS experiment aims to demonstrate that such an early warning system based on airglow measurements is possible.

The work may also benefit astronomical observations carried out by the telescopes at Paranal. Airglow emission can affect certain kinds of observations, and while astronomers have developed techniques to mitigate this, OASIS may be of further help. First, knowing the level of airglow in real time –– and potentially forecasting it –– could help to optimise how observations are scheduled. Second, the independent measurements from OASIS could help improve the methods currently used to remove airglow from astronomical data.

OASIS also aims to investigate turbulence in the atmosphere due to breaking gravity waves, which are of lower frequency than sound waves and generated by mountain ranges. Observations taken by OASIS in Paranal will complement over 10 years of previous research performed by the DLR with the Virtual Alpine Observatory project (VAO) and can both improve climate forecasting and further researchers’ understanding of climate signals.

More about OASIS

• Read more about the OASIS project on the DLR webpage

Instruments