Scientists detect Marsquakes by analyzing ground vibrations recorded by NASA’s InSight lander and checking whether their waveforms fit a seismic event rather than wind or other environmental noise. They estimate a quake’s distance from the gap between P- and S-wave arrivals, and sometimes estimate its direction from wave polarization. Because InSight used one seismometer station, many events could not be located as precisely as earthquakes monitored by networks on Earth.
How scientists detect a Marsquake
InSight’s Seismic Experiment for Interior Structure (SEIS) measured vibrations from quakes, impacts, and activity at or above the Martian surface. A quake sends body waves through the planet and surface waves along the ground. Seismologists inspect the recorded waveform and the timing and character of its arrivals to decide whether a signal is seismic and what kind of event may have caused it. NASA’s InSight science press kit describes SEIS and the mission’s approach to studying Mars’ interior.
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Separating seismic waves from wind and other noise
A vibration recorded by SEIS is not automatically a quake. InSight’s first likely Marsquake was recorded on April 6, 2019 (sol 128), but scientists were still determining whether it came from inside Mars or from forces above the surface, such as wind. Wind, atmospheric pressure, and magnetic measurements help scientists assess non-seismic disturbances. SEIS also had a vacuum vessel, and the lander used a Wind and Thermal Shield to reduce some environmental effects. NASA’s science press kit and its report on InSight’s first likely Marsquake explain these observations.
How scientists estimate where a quake happened
Location involves estimating both how far away a source was and, when the waveform allows, the direction it came from. On Earth, multiple stations can compare arrival times to triangulate an earthquake. InSight had only one station, so it lacked that ordinary network geometry; scientists combine clues from the single recording only when the data support them.
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P–S timing gives a distance clue
P waves (primary waves) and S waves (secondary waves) travel at different speeds and produce motion in different directions. The time between their arrivals provides an indication of source distance: a larger gap generally means the waves traveled farther. It is not a direct ruler, because wave speeds vary with the materials the waves cross inside Mars. NASA’s InSight science press kit describes the wave observations used to investigate the planet.
Wave polarization can add direction
When the signal is suitable, scientists can use the polarization—the direction in which the ground moves as waves arrive—to estimate a back azimuth, or direction toward the source. The Marsquake Service combines distance and back-azimuth estimates into a location when both can be determined reliably; it does not assign a back azimuth to most events. A 2022 polarization-analysis preprint examined high-quality events recorded through October 2021 and estimated back azimuths for 24 events, including 16 without a Marsquake Service back azimuth. The authors placed most of those events east of InSight, in the general Cerberus Fossae region. This is a result for that study and its method, not a count of all located Marsquakes. Zenhäusern and colleagues’ 2022 preprint gives the analysis.
Orbital images can independently locate an impact
An impact is a special case: if a fresh crater can be identified in orbital images, its surface position offers an independent location to compare with the seismic record. NASA reported an event correlated with a fresh crater in Cerberus Fossae about 1,640 kilometers from InSight. To find candidates, a machine-learning tool helped sift images from the Mars Reconnaissance Orbiter’s Context Camera for possible impact sites, which scientists could then check with follow-up imaging. NASA’s impact-correlation report describes the match and image search.
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1Clear out junk files and repair common Windows errors2Scan for outdated or missing drivers - takes under a minute3Repair Windows errors before they cause bigger problemsWhy many Marsquakes cannot be precisely located
- One station gives limited geometry. Without readings from a network of sites, distance and direction must be inferred from the waveform at InSight rather than ordinary multi-station triangulation.
- Direction is not always readable. Back azimuth is available only when the signal supports a reliable polarization estimate, and it is not assigned to most events.
- Wave travel depends on Mars’ interior. Distance estimates rely on wave speeds through the materials the waves crossed.
- Some sources are harder to detect. Farside waves can lose energy or be diverted as they travel through Mars, and some regions create seismic shadow zones. NASA quoted University of Bristol Earth scientist Jessica Irving: “Farside quakes are intrinsically harder to detect because a great deal of energy is lost or diverted away as seismic waves travel through the planet.” NASA’s report on farside quakes explains the challenge.
NASA’s undated mission summary reports that InSight measured over 1,300 seismic events, and that over 50 had signals clear enough for the team to derive information about their location. The largest cluster of high-quality events came from Cerberus Fossae. Those figures describe NASA’s categories in its InSight mission summary; they are not a universal location success rate for Mars missions.
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A magnitude estimate and a location are separate results. NASA reported an estimated magnitude 5 for the May 4, 2022 quake, while noting at the time that the team still needed to study it further to provide details such as its location and source. NASA/JPL’s report on the event illustrates why detecting or measuring a quake does not necessarily mean its source has been fully located.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.What a Marsquake location does—and does not—mean
A location is an inference whose strength depends on the event’s waveform and the clues available. P–S timing can indicate distance; polarization may add direction; and a visible impact crater can provide a separate surface coordinate. These methods do not yield a precise epicenter for every event. The cited NASA and study sources do not establish one numerical location-error range that applies to all Marsquakes.
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