The NASA InSight mission observed over 2000 marsquakes in the course of its three year mission. These quakes varied in magnitude between 1.5 and 4.5, as well as in spectral content. We present a simple framework to describe the spectral characteristics of all observed marsquakes, based on source process; propagation through the mantle or crust; and local, receiver-side amplification. We assign to each quake an objective measure of its amplitude, as well as the spectral decay created by the duration of the rupture and the dampening of high frequencies due to visco-elastic attenuation. Together, this allows us to obtain characteristic patterns of the whole marsquake dataset, e.g. in terms of event magnitudes, source size, and - for quakes caused by meteoritic impacts - crater size. We show that a significant fraction of all marsquakes - the high-frequency quakes - form a swarm that is likely not caused by tectonic processes in rocks. Our analysis allows separation of the whole marsquake catalogue into three event classes, of tectonic quakes, meteoritic impacts, and swarm events. We finally conclude that the largest marsquake, S1222a, most likely belongs to the group of meteoritic impacts.

SUMMARY X. Huang et al. reported the detection of 67 teleseismic marsquakes identified by P- and S-wave arrivals. The authors used a deep learning phase picker trained on local earthquake data and applied it to narrow-bandpass filtered seismic data recorded by NASA’s InSight seismometer, making use of similarities between local earthquake and teleiseismic marsquake recordings when adjusting for sampling rate and S-P timescaling relations. We review all detections as similarly done for the Marsquake Service catalogue and other studies on this data set, using the complementary wind and pressure data recorded by InSight. As these auxiliary data were not recorded in the second half of the mission, we also infer wind contamination from bandwidths in the seismic data that contain wind-sensitive lander modes. Additionally, we analyse the signal polarization to compare it with the expected characteristics of P and S waves and the background noise. Our review indicates that all 67 detections reported by the authors correspond to atmospheric noise. In most cases, the detections relate to the seismic signature of small wind bursts followed by larger wind bursts, onsets of which are interpreted as P and S waves by the authors. Further, we show that if these events were interpreted as genuine marsquakes, their inferred epicentral distance distribution would not match typical marsquake distances, while their magnitudes would make them the largest events of the catalogue. For future studies that deal with seismic event detection and interpretation from InSight, we recommend a careful consideration of the established event and noise signal markers described in this comment and in the literature to avoid misinterpretation of noise as event signals.

NASA's InSight mission has provided an unprecedented snapshot of Mars' seismicity, despite data analysis challenges arising from low signal-to-noise ratios (SNR) and single-station constraints. High frequency (HF) events-the most common type-were initially assumed to propagate through shallow crustal layers. However, several impacts that occurred late in the mission provided independent distance constraints, indicating that HF event energy must have propagated through the mantle. We analyzed the full HF data set using an extended catalog and denoised waveforms derived with deep learning (DL) techniques. Using a DL ensemble, we picked phase arrivals on denoised envelopes and estimated SNR-dependent pick timing uncertainties based on the removed noise. We computed distances consistent with mantle paths using the latest Mars interior models, while the back azimuth remained inconclusive due to local resonance dominating the HF bandwidth. We compared and grouped HF recordings by their similarity and investigated how attenuation properties shape their envelopes. Additionally, we re-calibrated and assigned magnitudes for the extended catalog. Overall, we (re-)located 1,430 HF events clustered between epicentral distances of around 1,600-3,600 km, but without constraints on the back azimuth, their source region remains speculative. Based on spatiotemporal similarities, we attributed a subset of 1,357 events to a common source region and labeled them as swarm events. The analysis of envelope shape confirms and extends previous results of stratified attenuation properties. Swarm events, with magnitudes between 1.5 and 2.5, are cumulatively equivalent to a single magnitude 4 event and show a high -value and clear seasonal trends in seismicity.

In the immediate aftermath of devastating earthquakes such as in the 6 February 2023 Kahramanmara sequence in southcentral T & uuml;rkiye, key stakeholders and the public demand timely and accurate earthquake information. Especially for large events, finite-fault models provide important insights into the rupture process and enable interpretation of the observed ground shaking, which can improve situational awareness and facilitate rapid assessment of future hazards. Using strong-motion waveforms recorded during the Kahramanmara sequence, we simulate a real-time playback and calculate how a finite-source model computed with the Finite-fault rupture Detector (FinDer) algorithm would evolve for the Mw w 7.8 Pazarc & imath;k, & imath; k, Mw w 7.6 Elbistan, and Mw w 6.4 Yaylada & gbreve;& imath; & gbreve;& imath; earthquakes. Using template matching FinDer compares observed and predicted ground-motion acceleration amplitudes to determine the orientation and spatial extent of fault rupture. We test both generic crustal and fault-specific templates from ground-motion models and rupture geometries of the east Anatolian and & Ccedil;ardak- S & uuml;rg & uuml; faults. In the second step, we estimate the seismic slip along the source models from the backprojection of the seismic displacement amplitudes. The algorithms achieve excellent performance for all three earthquakes, and the final source models and slip profiles available within tens of seconds of the rupture nucleation match well with models computed days to weeks after the events occurred. The temporal evolution of the source models for the Pazarc & imath;k & imath; k and Elbistan earthquakes suggests that FinDer can provide insight into the rupture kinematics of large earthquakes. Cascading instrument failures as well as power and data telemetry interruptions during the Pazarc & imath;k & imath; k earthquake led to an early termination of signals at a significant number of near-source stations. We show that FinDer is robust enough to cope with this type of degradation in network performance that can occur in large earthquakes, in general.

SUMMARY The analysis of seismic events recorded by NASA’s InSight seismometer remains challenging, given their commonly low magnitudes and large epicentral distances, and concurrently, strongly varying background noise. These factors collectively result in low signal-to-noise ratios (SNR) across most event recordings. We use a deep learning denoising approach to mitigate the noise contamination, aiming to enhance the data analysis and the seismic event catalogue. Our systematic tests demonstrate that denoising performs comparable to fine-tuned bandpass filtering at high SNRs, but clearly outperforms it at low SNRs with respect to accurate waveform and amplitude retrieval, as well as onset picking. We review the denoised waveform data of all 98 low-frequency events in the Marsquake Service catalogue version 14, and improve their location when possible through the identification of phase picks and backazimuths, while ensuring consistency with the raw data. We demonstrate that several event waveforms can be explained by marsquake doublets—two similarly strong quakes in spatio-temporal proximity that result in overlapping waveforms at InSight—and we locate them in Cerberus Fossae (CF). Additionally, we identify and investigate aftershocks and an event sequence consisting of numerous relatively high magnitude marsquakes occurring within hours at epicentral distances beyond CF. As a result of this review and interpretation, we extend the catalogue in event numbers ($+$8 per cent), in events with epicentral distances and magnitudes ($+$50 per cent), and events with backazimuths and a resulting full locations ($+$46 per cent), leading to a more comprehensive description of Martian seismicity.

The number density of impact craters on a planetary surface is used to determine its age, which requires a model for the production rate of craters of different sizes. On Mars, however, estimates of the production rate of small craters (<60 m) from orbital imagery and from extrapolation of lunar impact data do not match. Here we provide a new independent estimate of the impact rate by analysing the seismic events recorded by the seismometer onboard NASA's InSight lander. Some previously confirmed seismically detected impacts are part of a larger class of marsquakes (very high frequency, VF). Although a non-impact origin cannot be definitively excluded for each VF event, we show that the VF class as a whole is plausibly caused by meteorite impacts. We use an empirical scaling relationship to convert between seismic moment and crater diameter. Applying area and time corrections to derive a global impact rate, we find that 280-360 craters >8 m diameter are formed globally per year, consistent with previously published chronology model rates and above the rates derived from freshly imaged craters. Our work shows that seismology is an effective tool for determining meteoroid impact rates and complements other methods such as orbital imaging.

After ~4 years of deployment on the martian surface monitoring the planet’s ground motion, the InSight seismometer is now retired. Here, we review the procedures and methods the Marsquake Service (MQS) used to curate the seismic event catalog and describe the content of the catalog. The marsquake catalogue is different from normal catalogues on Earth as it aims to provide the authoritative catalog for the mission, covering the entire planet, using only a single station. As of January 1st, 2023, the MQS catalog contains 1319 seismic events of which 6 are known meteorite impacts. We have also identified 1383 superhigh frequency events that are interpreted as thermal cracking nearby the InSight lander. Late in the project large distant events occurred that allowed MQS to detect surface waves. Multiple events have been associated as impacts using orbital imaging, confirming the MQS single station location procedures. All of these new seismic phases have contributed to advance our understanding of the internal structure of Mars. The marsquake S1222a, the largest event recorded during the mission (MW 4.7) occurred in March 2022 and is also documented in our latest MQS catalog, V13, with many associated seismic phases including both Rayleigh and Love waves, their first-order overtones, and multi-orbiting surface waves that have not been identified in other marsquake records from our previous catalogues. The InSight mission is now closed but the MQS operation continues to analyze the ~4 years of seismic recordings on Mars and a final catalog, including event-specific products such as filter banks, and spectra, is in preparation. This final catalog will inform capabilities and field strategies in geophysical explorations for future martian science missions.

The crater density on planetary surfaces is used to determine their ages throughout the solar system, which requires a model for the rate of meteorite impacts of different sizes. For craters smaller than 30 meters, this rate has been observed from the generation of new craters in repeated orbital images. For larger craters, the rate was extrapolated from the lunar surface ages, taking into account the atmospheric removal of small craters. It has been observed that both estimates do not match for crater diameters smaller than 30 meters. The NASA InSight seismometer SEIS provided a new independent constraint, when it recorded seismic signals of several impacts during its mission. These confirmed impacts are part of a larger class of marsquakes (Very High Frequency, VF), all of which have characteristics consistent with an impact origin. We show that these VFs are plausibly caused by meteorite impacts and derive the impact rate required to explain their numbers. An empirical scaling relationship is used to convert between seismic moment and crater diameter. We apply area and time corrections to derive a global impact rate and find that the derived rate is 210--290 craters >8m globally per year, consistent with previously published chronology model rates and above the rates derived from freshly imaged craters.

After more than 4 Earth years of operation on the martian surface monitoring the planet’s ground vibrations, the InSight’s seismometer is now retired. Throughout the mission, analyses of body waves from marsquakes and impacts have led to important discoveries about the martian interior structure of the crust, mantle, and core. Recent detection of surface waves, together with gravimetric modeling enabled the characterization of crustal structure variations away from the InSight landing site and showed that average crustal velocity and density structure is similar between the northern lowlands and the southern highlands. Especially for the observed overtones and multi-orbiting surface waves in S1222a, we find the depth sensitivity expands down to the uppermost mantle close to 90 km. Furthermore, our 3D wavefield simulations show significantly broadened volumetric sensitivity of the higher-orbit surface waves. These new constraints obtained by our surface wave analyses provide an important opportunity not only to refine and verify our previous radially symmetric models of the planet’s interior structure but also to improve understanding of seismo-tectonic environments on Mars. Here, we summarize our recent effort in the analyses of surface waves on Mars and discuss the inferred crustal property and its global implications.

Abstract We report observations of Rayleigh waves that orbit around Mars up to three times following the S1222a marsquake. Averaging these signals, we find the largest amplitude signals at 30 and 85 s central period, propagating with distinctly different group velocities of 2.9 and 3.8 km/s, respectively. The group velocities constraining the average crustal thickness beneath the great circle path rule out the majority of previous crustal models of Mars that have a >200 kg/m3 density contrast across the equatorial dichotomy between northern lowlands and southern highlands. We find that the thickness of the Martian crust is 42–56 km on average, and thus thicker than the crusts of the Earth and Moon. Considered with the context of thermal evolution models, a thick Martian crust suggests that the crust must contain 50%–70% of the total heat production to explain present‐day local melt zones in the interior of Mars.

NASA's InSight has detected a large magnitude seismic event, labeled S1222a. The event has a moment magnitude of M(W)(Ma)4.7, with five times more seismic moment compared to the second largest event. The event is so large that features are clearly observed that were not seen in any previously detected events. In addition to body phases and Rayleigh waves, we also see Love waves, minor arc surface wave overtones, and multi-orbit surface waves. At long periods, the coda event exceeds 10 hr. The event locates close to the North-South dichotomy and outside the tectonically active Cerberus Fossae region. S1222a does not show any evident geological or tectonic features. The event is extremely rich in frequency content, extending from below 1/30 Hz up to 35 Hz. The event was classified as a broadband type event; we also observe coda decay and polarization similar to that of very high frequency type events. Plain Language Summary After 3 years of seismic monitoring of Mars by InSight Seismic Experiment for Interior Structure instrument, we detected a marsquake largest ever observed during the mission. The event is larger by factor of 5 in seismic moment compared to previously detected events. With such an energetic event, we discovered various seismic features that was never observed before. For the first time, we were able to detect body waves and surface waves with their overtones. The large variety of detected seismic phases will enable us to probe the internal structure of Mars. Second, the event was located outside a well-known seismically active region of Cerberus Fossae. This might indicate that event do not come from the same fault system with other major marsquakes. Finally, this event shows simultaneously features of marsquakes that were previously classified into different types. S1222a is classified as a broadband event with a wide frequency range of seismic energy. At the same time, the coda shape and decay at high frequency resembles that of very high frequency type events. It was an open question how different types of marsquakes are excited of what makes such differences and such event will be a key to uncover such mystery of marsquakes.

Marsquake recordings by NASA’s InSight seismometer often have low signal-to-noise ratios (SNR) owing to low marsquake amplitudes - only a handful of events are over M3.5 and epicentral distances are large, due to the single station being located in a seismically quiet region, and highly fluctuating atmospheric, spacecraft and instrumental noise signals.We have previously shown [1] how deep convolutional neural networks (CNN) can be used for 1) event detection - thereby producing an event catalogue consistent with the manually curated catalogue by the Marsquake Service (MQS) [2], and further extending it from 1297 to 2079 seismic events - as well as for 2) separating event and noise signals in time-frequency domain. Due to the low number of events readily-available for network training, we trained the CNN on synthetic event data combined with recorded InSight noise.Here, we construct a semi-synthetic data set (with real marsquake & noise data) to assess the denoising performance of the CNN w.r.t. to various evaluation metrics such as SNR, signal-distortion-ratio, cross-correlation, and peak amplitude of the recovered event waveforms, and compare modifications of the CNN architecture and the training data set.For a large number of identified events [1,2] no distance estimates are available (or only with high uncertainty), and for all but a small subset the back azimuth is unclear, as the relatively high background noise often obscures this information in the waveforms. We explore how the denoised waveforms can support the phase picking and polarisation analysis of marsquakes, and with that their localisation, as well as their general characterisation. References:[1] Dahmen et al. (2022), doi: 10.1029/2022JE007503[2] Ceylan et al. (2022), doi: 10.1016/j.pepi.2022.106943

InSight’s seismometers recorded more than 1300 events. Ninety-eight of these, named the low-frequency family, show energy predominantly below 1 Hz down to ∼0.125 Hz. The Marsquake Service identified seismic phases and computed distances for 42 of these marsquakes, 26 of which have backazimuths. Hence, the locations of the majority of low-frequency family events remain undetermined. Here, we use an envelope shape similarity approach to determine event classes and distances, and introduce an alternative method to estimate the backazimuth. In our similarity approach, we use the highest quality marsquakes with well-constrained distance estimates as templates, including the largest event S1222a, and assign distances to marsquakes with relatively high signal-to-noise ratio based on their similarities to the template events. The resulting enhanced catalog allows us to re-evaluate the seismicity of Mars. We find the Valles Marineris region to be more active than initially perceived, where only a single marsquake (S0976a) had previously been located. We relocated two marsquakes using new backazimuth estimates, which had reported distances of ∼90o, in the SW of the Tharsis region, possibly at Olympus Mons. In addition, two marsquakes with little or no S-wave energy have been located in the NE of the Elysium Bulge. Event epicenters in Cerberus Fossae follow a North-South trend due to uncertainties in location, while the fault system is in the NW-SE direction; therefore, these events are re-projected along the observed fault system.

Abstract Using seismic recordings of event S1222a, we measure dispersion curves of Rayleigh and Love waves, including their first overtones, and invert these for shear velocity (VS) and radial anisotropic structure of the Martian crust. The crustal structure along the topographic dichotomy is characterized by a fairly uniform vertically polarized shear velocity (VSV) of 3.17 km/s between ∼5 and 30 km depth, compatible with the previous study by Kim et al. (2022), https://doi.org/10.1126/science.abq7157. Radial anisotropy as large as 12% (VSH > VSV) is required in the crust between 5 and 40 km depth. At greater depths, we observe a large discontinuity near 63 ± 10 km, below which VSV reaches 4.1 km/s. We interpret this velocity increase as the crust‐mantle boundary along the path. Combined gravimetric modeling suggests that the observed average crustal thickness favors the absence of large‐scale density differences across the topographic dichotomy.

The current Martian cratering rate has been determined either from repeated orbital imaging (e.g.[1][2]), or using lunar rates extended to Mars in combination with crater counting [3]. Eight seismic events detected by the NASA InSight seismometer have been confirmed as impacts by orbital imaging [4]. Six of those events are part of the Very High Frequency (VF) group of marsquakes, which consists of 70 events in total. The impact signals are very similar to other VF events, suggesting that more or all VF events could be impact related. The unique characteristics of VF events, such as a long seismic coda interpreted as a result of shallow source in a strongly scattering near-surface layer [5] and their temporal and spatial distributions, are consistent with impact origin.Assuming all high quality VF events are impacts allows us to place a novel constraint on the impact rate on Mars, independent of the formation of easy-to-spot large blast zones, necessary to identify fresh craters in orbital images. We test the compatibility with the existing cratering rate estimates by using two approaches to derive a first seismically constrained impact rate for Mars. First, we use the Gutenberg-Richter law to determine the slope of the VF event magnitude-frequency distribution. The impact rate is derived by applying a relationship between seismic moment and crater diameter [6]. We refine our estimates by extrapolating the detectability of each event using a semi-empirical relationship between crater size and seismic amplitude [6]. We find that both approaches give similar rates, varying slightly depending on the detectability conditions assumed by each method. The cumulative rates N(D≥8m) = 1-4x10-6 /km2/yr are higher than those from previous imaging studies, but consistent with isochron rates [3].The discrepancy with imaging-based rates could indicate that there are impacts which are missed in imagery due to absent blast zones or that are located in unfavourable terrain, unaccounted for in the imaging-based area correction. References:[1] Daubar et al. (2013). doi: 10.1016/j.icarus.2013.04.009[2] Daubar et al. (2022). doi: 10.1029/2021JE007145[3] Hartmann (2005). doi: 10.1016/j.icarus.2004.11.023[4] Daubar et al. (2023). InSight Seismic Events Confirmed as Impacts Thus Far. Lunar and Planetary Science Conference 2023 abstract.[5] van Driel et al. (2021). doi: 10.1029/2020JE006670[6] Wójcicka et al. (2023). Impact Rate on Mars Implied by Seismic Observations. Lunar and Planetary Science Conference 2023 abstract.

The seismic activity of a planet can be described by the corner magnitude, events larger than which are extremely unlikely, and the seismic moment rate, the long-term average of annual seismic moment release. Marsquake S1222a proves large enough to be representative of the global activity of Mars and places observational constraints on the moment rate. The magnitude-frequency distribution of relevant Marsquakes indicates a b $b$-value of 1.06. The moment rate is likely between 1.55x1015Nm/a $1.55\times {10}<^>{15}\mathrm{N}\mathrm{m}/\mathrm{a}$ and 1.97x1018Nm/a $1.97\times {10}<^>{18}\mathrm{N}\mathrm{m}/\mathrm{a}$, with a marginal distribution peaking at 4.9x1016Nm/a $4.9\times {10}<^>{16}\mathrm{N}\mathrm{m}/\mathrm{a}$. Comparing this with pre-InSight estimations shows that these tended to overestimate the moment rate, and that 30% or more of the tectonic deformation may occur silently, whereas the seismicity is probably restricted to localized centers rather than spread over the entire planet.

We present the first observations of seismic waves propagating through the core of Mars. These observations, made using seismic data collected by the InSight geophysical mission, have allowed us to construct the first seismically constrained models for the elastic properties of Mars' core. We observe core-transiting seismic phase SKS from two farside seismic events detected on Mars and measure the travel times of SKS relative to mantle traversing body waves. SKS travels through the core as a compressional wave, providing information about bulk modulus and density. We perform probabilistic inversions using the core-sensitive relative travel times together with gross geophysical data and travel times from other, more proximal, seismic events to seek the equation of state parameters that best describe the liquid iron-alloy core. Our inversions provide constraints on the velocities in Mars' core and are used to develop the first seismically based estimates of its composition. We show that models informed by our SKS data favor a somewhat smaller (median core radius = 1,780 to 1,810 km) and denser (core density = 6.2 to 6.3 g/cm3) core compared to previous estimates, with a P-wave velocity of 4.9 to 5.0 km/s at the core-mantle boundary, with the composition and structure of the mantle as a dominant source of uncertainty. We infer from our models that Mars' core contains a median of 20 to 22 wt% light alloying elements when we consider sulfur, oxygen, carbon, and hydrogen. These data can be used to inform models of planetary accretion, composition, and evolution.

The S1222a marsquake detected by InSight on 4 May 2022 was the largest of the mission, at MwMa 4.7. Given its resemblance to two other large seismic events (S1000a and S1094b), which were associated with the formation of fresh craters, we undertook a search for a fresh crater associated with S1222a. Such a crater would be expected to be similar to 300 m in diameter and have a blast zone on the order of 180 km across. Orbital images were targeted and searched as part of an international, multi-mission effort. Comprehensive analysis of the area using low- and medium-resolution images reveals no relevant transient atmospheric phenomena and no fresh blast zone. High-resolution coverage of the epicentral area from most spacecraft are more limited, but no fresh crater or other evidence of a new impact have been identified in those images either. We thus conclude that the S1222a event was highly likely of tectonic origin. During its time on Mars, NASA's InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) mission recorded over 1,300 seismic events, known as "marsquakes." Of these, a number were identified as coming from meteoroid impact cratering events on the surface. The largest event identified by InSight, labeled S1222a, bore some similarities to two large impact events recorded earlier in the mission. In order to investigate whether the S1222a event might also have been caused by an impact event, we undertook a comprehensive search of the region in which the marsquake occurred. We did not identify any fresh craters in the area, implying that the marsquake was likely caused by geological processes. The S1222a marsquake detected by InSight on 4 May 2022 somewhat resembled previous impact-generated eventsWe performed an image search in the estimated source region, using data from multiple Mars orbiter missionsNo new impact crater has been discovered in this area, pointing to a tectonic origin for the quake

Abstract Prior to the 2018 landing of the InSight mission, the InSight science team proposed locating Marsquakes using multiple orbit surface waves, independent of seismic velocity models, for events larger than MW4.6. The S1222a MW4.7 of 4 May 2022 is the largest Marsquake recorded and the first large enough for this method. Group arrivals of the first three orbits of Rayleigh waves are determined to derive the group velocity, epicentral distance, and origin time. The mean distance of 36.9 ± 0.3° agrees with the Marsquake Service (MQS) distance based on body wave measurements of 37.0 ± 1.6°. The origin time from surface waves is systematically later than the MQS origin time by 20 s. Backazimuth estimation is similar to body wave estimations from MQS although suggesting a shift to the south. Backazimuth estimates from R2 and R3 are more scattered, but do show clear elliptical motion.