Recording earthquakes on the Moon, Mars - and now in LUNA
On 6 February, we installed a broadband seismometer in LUNA and started operations. The seismometer is located on the floor of the hall under the regolith layer and will provide continuous data on the level of seismic background noise in the hall as well as on typical signals from the surrounding area (CGN airport, traffic and machine operations on the DLR campus, etc.). These can support users who want to test their own seismic instrumentation for the Moon in LUNA. During the weekend, we also recorded several quakes from the currently seismically active region north-east of Santorini (Greece), as well as a magnitude 7.6 quake near the Cayman Islands (Caribbean, approx. 8450 km away). This strong earthquake caused the ground in Cologne to move for over 4 hours.
As with space missions, the LUNA seismometer provides not only seismic data but also housekeeping telemetry, e.g. on the power supply and temperature of the sensor and electronics, which will be integrated into the LUNA Mission Control System in the next step. In the future, the seismic data will also be publicly available via EIDA (European Integrated Data Archive).
An interesting fact about the quakes in Greece is that quakes of comparable strength (magnitude 5.2) and at a similar distance (approx. 2150 km) have also been recorded by the Apollo seismometers on the Moon and during the InSight mission on Mars. When comparing the recordings, the background noise on the Moon and Mars is noticeably lower – there are no oceans, only a comparatively thin atmosphere or none at all, and no human activity. What is also striking about the lunar data is that the amplitudes on the horizontal components are significantly greater than on the vertical component, and the signals last significantly longer than those of both the earth- or marsquake. This is due to the thick lunar regolith layer, which strongly scatters waves, as well as the fact that the crust on the moon is extremely dry and wave propagation is therefore less attenuated.
Quakes of a comparable magnitude to those on the Cayman Islands are not expected on the Moon. Nevertheless, moonquakes with a magnitude such as that of SMQ 26 shown in the figure can also pose a threat to infrastructure in the immediate vicinity. A better understanding of the seismic activity at the south pole of the Moon is one of the reasons why the Artemis III astronauts will also install a seismometer (Lunar Environmental Monitoring Station – LEMS) at their landing site.
