We present inversions for the structure of Mars using the first Martian seismic record collected by the InSight lander. We identified and used arrival times of direct, multiples, and depth phases of ...body waves, for 17 marsquakes to constrain the quake locations and the one‐dimensional average interior structure of Mars. We found the marsquake hypocenters to be shallower than 40 km depth, most of them being located in the Cerberus Fossae graben system, which could be a source of marsquakes. Our results show a significant velocity jump between the upper and the lower part of the crust, interpreted as the transition between intrusive and extrusive rocks. The lower crust makes up a significant fraction of the crust, with seismic velocities compatible with those of mafic to ultramafic rocks. Additional constraints on the crustal thickness from previous seismic analyses, combined with modeling relying on gravity and topography measurements, yield constraints on the present‐day thermochemical state of Mars and on its long‐term history. Our most constrained inversion results indicate a present‐day surface heat flux of 22 ± 1 mW/m2, a relatively hot mantle (potential temperature: 1740 ± 90 K) and a thick lithosphere (540 ± 120 km), associated with a lithospheric thermal gradient of 1.9 ± 0.3 K/km. These results are compatible with recent seismic studies using a reduced data set and different inversion approaches, confirming that Mars' potential mantle temperature was initially relatively cold (1780 ± 50 K) compared to that of its present‐day state, and that its crust contains 10–12 times more heat‐producing elements than the primitive mantle.
Plain Language Summary
The seismic recordings from the InSight mission have proven that Mars is an active planet. Among the several 100s of detected marsquakes, 17 have a sufficient quality to constrain the internal structure of Mars. We found that most of these marsquakes occurred at depths shallower than 40 km, and are located in the Cerberus Fossae region. There are faults in this area, which could be a source of quakes. An important finding is that as on Earth, the crust is made of two types of rocks formed when hot molten material is cooling, quickly near the surface, and slowly in depth because temperature under the planet's surface is higher. Combining our seismic data with other independent geophysical measurements, we are able to reconstruct the thermal history of Mars. Our results indicate that Mars has a relatively hot mantle, and that the uppermost mantle temperature was initially colder than at the present.
Key Points
We inverted for the 1D structure of Mars and for the quake locations using a new 17 events body wave data set from the InSight mission
Our novel inversion scheme constrains the surface heat flux to 22 ± 1 mW/m2 and a lithospheric thermal gradient of 1.9 ± 0.3 K/km
Our results suggest a mantle initially at 1780 ± 50 K, and a crust 10–12 times enriched in radiogenic elements relative to the bulk mantle
Ground motion from seismic events detected by the SEIS/InSight seismometer on Mars could potentially trigger dust avalanches. Our research strongly suggests that the seismic event S1000a may have ...triggered a significant number of dust avalanches. In contrast, following the seismic event S1222a, there was only a modest increase in avalanche occurrences. Orbital observations of the area surrounding the projected location of the S1222a quake reveal notable topographic features, such as North-South ridges and impact craters. We utilize orbital imagery to evaluate the rate of avalanches and explore how the S1222a event might have influenced this rate. The S1222a event appears to be a plausible factor contributing to the observed increase in avalanches. Our further analysis of the epicenter location aims to clarify how it aligns with the avalanches’ spatial distribution, offering insights into the regional topography.
•On May 4, 2022, a major martian seismic event was recorded.•We identified possibly seismically induced dust avalanches in the area of the estimated epicenter.•We discuss avalanche triggering conditions and derive a possible epicenter location based on avalanche spatial density.
The Marsquake catalogue from InSight, sols 0–478 Clinton, John F.; Ceylan, Savas; van Driel, Martin ...
Physics of the earth and planetary interiors,
January 2021, 2021-01-00, 2021-01, Letnik:
310
Journal Article
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The InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) mission began collecting high quality seismic data on Mars in February 2019. This manuscript documents the ...seismicity observed by SEIS, InSight's seismometer, from this time until the end of March 2020. Within the InSight project, the Marsquake Service (MQS) is responsible for prompt review of all seismic data collected by InSight, detection of events that are likely to be of seismic origin, and curation and release of seismic catalogues. In the first year of data collection, MQS have identified 465 seismic events that we interpret to be from regional and teleseismic marsquakes. Seismic events are grouped into 2 different event families: the low frequency family is dominated by energy at long period below 1 s, and the high frequency family primarily include energy at and above 2.4 Hz. Event magnitudes, from Mars-specific scales, range from 1.3 to 3.7. A third class of events with very short duration but high frequency bursts have been observed 712 times. These are likely associated with a local source driven by thermal stresses. This paper describes the data collected so far in the mission and the procedures under which MQS operates; summarises the content of the current MQS seismic catalogue; and presents the key features of the events we have observed so far, using the largest events as examples.
•The Marsquake Service is providing updated catalogues of Martian seismicity as recorded on InSight.•465 distant marsquakes have been identified in the first 478 martian days (sol) since InSight landed.•This version of the catalogue includes an additional 712 events that may be due to local cracking from thermal forcing.
Abstract
For over three Earth years the Marsquake Service has been analyzing the data sent back from the Seismic Experiment for Interior Structure—the seismometer placed on the surface of Mars by ...NASA’s InSight lander. Although by October 2021, the Mars seismic catalog included 951 events, until recently all these events have been assessed as lying within a radius of 100° of InSight. Here we report two distant events that occurred within days of each other, located on the far side of Mars, giving us our first glimpse into Mars’ core shadow zone. The first event, recorded on 25 August 2021 (InSight sol 976), shows clear polarized arrivals that we interpret to be PP and SS phases at low frequencies and locates to Valles Marineris, 146° ± 7° from InSight. The second event, occurring on 18 September 2021 (sol 1000), has significantly more broadband energy with emergent PP and SS arrivals, and a weak phase arriving before PP that we interpret as Pdiff. Considering uncertain pick times and poorly constrained travel times for Pdiff, we estimate this event is at a distance between 107° and 147° from InSight. With magnitudes of MwMa 4.2 and 4.1, respectively, these are the largest seismic events recorded so far on Mars.
The NASA InSight mission on Mars is a unique opportunity to study atmospheric processes
both from orbit and in situ observations. We use post-landing high-resolution satellite images to monitor dust ...devil activity during the first 8 months of the mission. We perform mapping and semiautomatic detection of newly formed dust devil tracks and analyze their characteristics (sizes, azimuths, distances, and directions of motion).We find a large number of tracks appearing shortly after landing, followed by a significant decrease of activity during late winter, then a progressive increase during early spring. New tracks are characterized by dark linear, to slightly curvilinear, traces ranging from a few to more than 10 m wide. Tracks are oriented in the ambient wind direction, according to measurements made by InSight's meteorological sensors. The systematic analysis of dust devil tracks is useful to have a better understanding of atmospheric and aeolian activity around InSight.
Seasonal seismic activity on Mars Knapmeyer, M.; Stähler, S.C.; Daubar, I. ...
Earth and planetary science letters,
12/2021, Letnik:
576
Journal Article
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•InSight SEIS finds seasonal variations of “High Frequency” type Marsquake occurrence.•Likely driving forces are solar illumination, the CO2 ice cycle, or annual solar tides.•No relation to the ...orbital periods of Phobos and related tides is found.
The rate of occurrence of High Frequency (HF) marsquakes, as recorded by InSight at Homestead Hollow, Elysium Planitia, increased after about LS=33∘, and ceased almost completely by LS=187∘, following an apparently seasonal variation with a peak rate near aphelion. We define seismic rate models based on the declination of the Sun, annual solar tides, and the annual CO2 cycle as measured by atmospheric pressure. Evaluation of Akaike weights and evidence ratios shows that the declination of the Sun is the most likely, and the CO2 cycle the least likely driver of this seismic activity, although the discrimination is weak, and the occurrence of a few events in August 2020 is in favor for a triggering by CO2 ice load. We also show that no periodicity related to Phobos' orbit is present in the HF event sequence. Event rate forecasts are presented to allow further discrimination of candidate mechanisms from future observations.
The NASA InSight mission to Mars successfully landed on 26 November 2018 in Elysium Planitia. It aims to characterize the seismic activity and aid in the understanding of the internal structure of ...Mars. We focus on the Cerberus Fossae region, a giant fracture network ∼1,200 km long situated east of the InSight landing site where M ∼3 marsquakes were detected during the past 2 years. It is formed of five main fossae located on the southeast of the Elysium Mons volcanic rise. We perform a detailed mapping of the entire system based on high‐resolution satellite images and Digital Elevation Models. The refined cartography reveals a range of morphologies associated with dike activity at depth. Width and throw measurements of the fossae are linearly correlated, suggesting a possible tectonic control on the shapes of the fossae. Widths and throws decrease toward the east, indicating the long‐term direction of propagation of the dike‐induced graben system. They also give insights into the geometry at depth and how the possible faults and fractures are rooted in the crust. The exceptional preservation of the fossae allows us to detect up to four scales of segmentation, each formed by a similar number of 3–4 segments/subsegments. This generic distribution is comparable to continental faults and fractures on Earth. We anticipate higher stress and potential marsquakes within intersegment zones and at graben tips.
Plain Language Summary
The landing of the InSight mission on Mars and the deployment of its seismometer have renewed the interest of active Martian structures that could trigger seismic events. In this study, we focus on one of these structures, Cerberus Fossae, which is a large fracture network situated close to the landing site. We perform a detailed mapping of the fossae based on high‐resolution satellite images and present an analysis of their lateral segmentation and morphology. We assess an eastward direction of long‐term propagation of the fossae. We also find that the fossae are laterally segmented at four different scales: fossae are divided into major segments, which are themselves divided into secondary segments and so on. At each scale of segmentation, a similar number of three to four subsegments is found. This number is also observed along terrestrial fault systems. These results allow us to assess the overall and local stress concentrations along the fossae: we infer that those stresses are higher eastward near the tip of the fossae and at intersegment zones. Since marsquakes are difficult to locate precisely with a single seismic station, our study is an asset to reduce uncertainties and to better understand the source properties.
Key Points
Width and throw at Cerberus Fossae decrease from west to east, indicating the direction of long‐term propagation of the dike‐induced grabens
Cerberus Fossae are laterally divided into a similar number of major segments and sub‐segments, as observed along terrestrial fault systems
Understanding the long‐term propagation and segmentation of Cerberus Fossae helps to delineate marsquake locations during the InSight mission
The seismometer onboard InSight NASA Mars mission discovered a seismically active planet. We focused on the strongest event named S1222a (4 May 2022, Mw ∼ 4.7), which was recorded by the Very Broad ...Band sensors and associated channel ELYSE and is located 37.2° away from InSight. We use two different methods based on a point source approach for an elastic, horizontally layered medium to retrieve source parameters of S1222a. In the first case, the seismic moment tensor inversion of high‐frequency seismogram data is calculated using a matrix method for the direct waves. The process includes the generation of records in displacement using the frequency‐wavenumber integration technique. A method of inversion of the moment tensor of direct P‐ and S‐waves, less sensitive to path effects than reflected and transformed waves, is presented, which significantly increases the accuracy and reliability of the method. In the second case, tensors were calculated using common low‐frequency full‐waveform inversion and the tests to verify the plausibility of this solution obtained from the single station calculation were performed and the uncertainty estimations for inversions can be useful in future research.
Plain Language Summary
The paper presents the seismic moment tensor solution and the focal mechanism for the largest event S1222a (4 May 2022, magnitude Mw4.7) recorded at one seismic station on Mars. We consider two different basic approaches to address the problem of the unavoidable inaccuracy of seismic waves modeling: focusing only on direct waves and using low‐frequency full‐waveform inversion. The moment tensor and focal mechanism of the S1222a event were obtained, as well as the optimal depth of a source. Despite the range of possible, it is encouraging that independent studies based on different methodologies, and using different structural models, point to reasonable solutions. The estimates of the focal mechanism when the single‐station inversion is calculated are taken into account and the stability tests to verify our solutions were performed. The importance of this study lies in expanding the possibilities of how to calculate this kind of tasks.
Key Points
We consider two different methods based on a point source approach to retrieve source parameters of S1222a
A method of inversion of the moment tensor of direct waves, less sensitive to path effects than reflected and transformed waves, is presented
We obtained the results of seismic tensor solution and time‐independent focal mechanism
First Focal Mechanisms of Marsquakes Brinkman, Nienke; Stähler, Simon C.; Giardini, Domenico ...
Journal of geophysical research. Planets,
April 2021, Letnik:
126, Številka:
4
Journal Article
Recenzirano
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Since February 2019, NASA's InSight lander is recording seismic signals on the planet Mars, which, for the first time, allows to observe ongoing tectonic processes with geophysical methods. A number ...of Marsquakes have been located in the Cerberus Fossae graben system in Elysium Planitia and further west, in the Orcus Patera depression. We present a first study of the focal mechanisms of three well‐recorded events (S0173a, S0183a, S0235b) to determine the processes dominating in the source region. We infer for all three events a predominantly extensional setting. Our method is adapted to the case of a single, multicomponent receiver and based on fitting waveforms of P and S waves against synthetic seismograms computed for the initial crustal velocity model derived by the InSight team. We explore the uncertainty due to the single‐station limitation and find that even data recorded by one station constrains the mechanisms (reasonably) well. For the events in the Cerberus Fossae region (S0173a, S0235b) normal faulting with a relatively steep dipping fault plane is inferred, suggesting an extensional regime mainly oriented E‐W to NE‐SW. The fault regime in the Orcus Patera region is not determined uniquely because only the P wave can be used for the source inversion. However, we find that the P and weak S waves of the S0183a event show similar polarities to the event S0173, which indicates similar fault regimes.
Plain Language Summary
As time passes, the mysterious interior of Mars is slowly being unraveled due to the detection and analysis of Marsquakes recorded with a seismograph carried by the InSight lander. Close to 400 Marsquakes have so far been identified, yet only a handful of those show similarities to earthquakes. Those earth‐like events are located near the Cerberus Fossae and Orcus Patera regions. We take advantage of the similarity between Marsquakes and earthquakes and apply a methodology developed for earthquake characterization before seismic recorders became abundant on Earth. We find that the Marsquakes in these source regions are dominated by extensional rather than compressing features. This is important information to further understand what causes Marsquakes.
Key Points
We infer the tectonic setting in Cerberus Fossae on Mars by seismic source inversion
We present a robust inversion strategy for single‐station moment tensor inversion
Three Marsquakes recorded by InSight reveal a predominantly normal faulting regime
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