Seismic Experiment for Interior Structure

SEIS is expected to provide seismic measurements of marsquakes, enabling researchers to develop 3D structure maps of the deep interior.

On 24 December 2021, the seismometer for the InSight mission on Mars detected a large seismic event with a distinct signature.

The event was caused by a meteor impact on the surface of Mars, which was confirmed by satellite observations of a newly formed 150-meter crater.

Other onboard instruments working in synergy with SEIS are the Temperature and Winds for InSight module, the Heat Flow and Physical Properties Package, and the Rotation and Interior Structure Experiment.

[7] The seismometer readings were used to estimate a Martian geological crust thickness between 14 and 18 km (8.7 and 11.2 mi) at the Viking 2 lander site.

[8][9] A single possible candidate for a marsquake was recorded, although it was not confirmed due to the limitations of the design, and interference from other sources of vibration such as wind.

[16] Combination of data with results from the InSight radio science and orbital observations will allow for constraint of the deeper structure.

[24] There is a variety of single-site seismology techniques that can yield data, for example, the detection of an impact on the surface by a meteorite for which the location is identified.

Both Viking Mars landers in the 1970s had a seismometer (part is visible between the calibration targets), but deployment issues hampered meaningful geological data.
Artist's concept of the SEIS instrument deployed on the Martian surface (right-side). On the left is the HP 3 instrument burrowing below the surface.
Animation of the seismometer being lifted off the saucer by the robotic arm and placed on the surface of Mars
Illustration from the USGS of how P and S waves from an Earthquake make a shadow zone because of the core.
Fresh asteroid impact on Mars at 3°20′N 219°23′E  /  3.34°N 219.38°E  / 3.34; 219.38 – before /March 27 & after /March 28, 2012 ( MRO ) [ 25 ] It is hoped SEIS may be able to detect vibrations of a strong enough impact on Mars, and if the impact site is located, it allows even more understanding. [ 24 ]
Cutaway illustration showing interior components of SEIS