Review of the seismicity on Mars

Abstract

The InSight mission collected an astounding seismic dataset from Mars during more than four years of operation until it was retired in 12/2022. The Marsquake Service detected over 1300 seismic events. The largest marsquake reached magnitude 4.6. Two other significant events are distant impacts, with magnitudes M4.0 and 4.2 and crater diameters of 130 and 150 m respectively. We present the current understanding of the Martian seismicity and the different types of events observed on Mars.Low Frequency (LF) family are the largest events and include energy predominantly below 1 Hz. They are similar to teleseismic events on Earth, with clear P and S waves. The epicenter is known for about half of the LF events, fewer have constrained back-azimuth. Seismicity occurs at only a few spots around Mars - a large number of LF events are located at 26–30° at the volcanic Cerberus Fossae region. Two events lie beyond the core shadow and have PP and SS phases. High-frequency (HF) family exhibit energy predominantly at and above the 2.4 Hz local subsurface resonance. HF events generally have magnitudes below M2.5 and originate from central Cerberus Fossae. Likely these are shallow events associated with volcanic dykes. HF events have inter and intra seasonal trends not yet understood. A small number of HF events have higher frequency content, up to 20–30 Hz with amplification on the horizontal components, and are termed Very High Frequency (VF) events. The closest VF events include a distinctive acoustic signal, and remote imaging confirms they are impacts.