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Detection of a Martian Long Range Thermospheric Acoustic Wave by SEIS/InSight

Description: 

We show the first detection on InSight seismometer, SEIS, of a long range, long period thermospheric Acoustic wave generated by the large impact of Sol 1094, which occured at about 3460 km of epicentral distance. Although associated mostly to a pressure wave, the signal is detected by the 3 axis seismometer through compleance effect amplified by the landig site fabric tilt. We then model this signal by Normal mode summation. Normal modes are computed by taking into account the solid-atmosphere coupling and , in the atmosphere, viscosity and C O2 relaxation.

Both the normal modes and ray tracing shows that the signal is generated by acoustic waves trapped between the thermosphere and the martian surface, which bounce several times on the ground and are refracted up to about 100 km of altitude. This demonstrates that long period acoustic waves can propage thousand km away and at altitudes with extremely low densities.

We then invert the source associated to the entry and explosion of the 1094 impactor, which generated on the Ground a 150 m large crater. Although the waveform can be partialy retrieve by a near surface explosion, we show that such a source model request likely too large explosion yield. On the other hand, more complex source generated by both the entry supersonic cone and one or several explosions seems more likely and can be made with impactor with mass and entry velocities fitting much better the crater size constraints.

This observation demonstrate that acoustic signals of impacts can on Mars be detected at teleseismic distances and open new direction for future reprocessing of the InSight SEIS data.

Session: Planetary and Gravitational Wave Seismology [Poster]

Type: Poster

Date: 4/15/2026

Presentation Time: 08:00 AM (local time)

Presenting Author: Philippe H. Lognonné

Student Presenter: No

Invited Presentation: 

Poster Number: 135

Authors