Fig. 2: Comparison of seismograms of earthquakes, moonquakes, and marsquakes.

a Recording of an earthquake in Eastern Turkey of magnitude 6.1, source depth 12 km, at station BFO¹⁵ on March 8, 2010. The epicentral distance is about 2730 km. Various seismic phases, including P- and S- arrivals and surface waves, are clearly visible. b Recording of a shallow moonquake (depth: 50 km) of magnitude 4.07 on January 3, 1975, at Apollo 16. Epicentral distance is about 2690 km, similar to a, but the seismogram has a different, spindle-like shape. Scattering within the dry, porous crust masks any clear phase arrivals, and small attenuation leads to a prolonged waveform. c Marsquake S0235b recorded by SEIS¹³ on June 26, 2019, at an epicentral distance of about 1540 km, with a magnitude of 3.3. Clear P- and S-arrivals are readily apparent, but surface waves are missing, which could be related to source depth or scattering. d Marsquake S0128a recorded by SEIS¹³ on April 7, 2019, with an estimated magnitude between 1.8 and 2.3. This event contains high frequencies, has a spindle-like shape, and no clear phase arrivals. The large amplitudes starting at around 18 min are caused by motion of the robotic arm. This Mars seismograms show a decay time longer than that of Earth and shorter than or comparable to the Moon. This indicates that Mars’ attenuation is stronger than that of the Earth, but weaker than that of the Moon. As attenuation strongly depends on thermal conditions and volatile/water content, such difference may reflect the different environments of the three bodies. Note that the timescale is different in a and b, and c and d, respectively. Amplitudes are not to scale between the different subplots.