A marsquake is a quake which, much like an earthquake, is a shaking of the surface or interior of the planet. Such quakes may occur with a shift in the planet's interior, such as the result of plate tectonics, from which most quakes on Earth originate, or possibly from hotspots such as Olympus Mons or the Tharsis Montes. The detection and analysis of marsquakes are informative to probing the interior structure of Mars, as well as potentially identifying whether any of Mars's many volcanoes continue to be volcanically active. [1]
Quakes have been observed and well-documented on the Moon, and there is evidence of past quakes on Venus. Marsquakes were first detected but not confirmed by the Viking mission in 1976. [2] Marsquakes were detected and confirmed by the InSight mission in 2019. [3] Using InSight data and analysis, the Viking marsquakes were confirmed in 2023. [4] Compelling evidence has been found that Mars has in the past been seismically more active, with clear magnetic striping over a large region of southern Mars. Magnetic striping on Earth is often a sign of a region of particularly thin crust splitting and spreading, forming new land in the slowly separating rifts; a prime example of this being the Mid-Atlantic Ridge. However, no clear spreading ridge has been found in this region, suggesting that another, possibly non-seismic explanation may be needed.
The 4,000 km (2,500 mi) long canyon system, Valles Marineris, has been suggested to be the remnant of an ancient Martian strike-slip fault. [5] The first confirmed seismic event emanating from Valles Marineris, a quake with a magnitude of 4.2, was detected by InSight on 25 August 2021, proving it to be an active fault. [6]
The first attempts to detect seismic activity on Mars were with the Viking program with two landers, Viking 1 & 2 in 1976, with seismometers mounted on top of the lander. The seismometer on the Viking 1 lander failed. The Viking 2 seismometer collected data for 2100 hours (89 days) of data over 560 sols of lander recorded. [2] [7]
Viking 2 recorded two possible marsquakes on Sol 53 (daytime during windy period) and Sol 80 (nighttime during low wind period). Due to the inability to separate ground motion from wind-driven lander vibrations and the lack of other collaborating possible marsquakes, the Sol 53 and Sol 80 events could not be confirmed during the Viking mission. [7] [8] It was possible to rule out frequent and large marsquakes at that time. [9] The low detection rate and evaluation when the windspeed was low at the Viking 2 site, allowed limits to be placed on seismic activity on Mars. [10] [7]
In 2013, data from the InSight mission (see below) led to an increased interest in the Viking data set, and further analysis may reveal one of the largest collections of Mars dust devil detections. [7] In 2023, a re-evaluation of Viking 2 using InSight data and analysis, and Viking wind data, confirmed that the two Viking events on Sol 53 and 80 were marsquakes. [4]
The InSight Mars lander, launched in May 2018, landed on Mars on 26 November 2018 and deployed a seismometer called Seismic Experiment for Interior Structure (SEIS) on 19 December 2018 to search for marsquakes and analyze Mars's internal structure. Even if no seismic events are detected, the seismometer is expected to be sensitive enough to detect possibly several dozen meteors causing airbursts in Mars's atmosphere per year, as well as meteorite impacts. [11] It will also investigate how the Martian crust and mantle respond to the effects of meteorite impacts, which gives clues to the planet's inner structure. [12] [13] [14]
A faint seismic signal, believed to be a small marsquake, was measured and recorded by the InSight lander on 6 April 2019. [15] The lander's seismometer detected ground vibrations while three distinct kinds of sounds were recorded, according to NASA. Three other events were recorded on 14 March, 10 April, and 11 April, but these signals were even smaller and more ambiguous in origin, making it difficult to determine their cause. [16] [17]
On 4 May 2022, a large marsquake, estimated at magnitude 5, was detected by the seismometer on the InSight lander. [18] In October 2023 the results of a collaborative international project to scan the surface of Mars for a new impact crater created at the time of the 4 May 2022 seismic event, known as S1222a, was published. It was estimated that a crater of at least 300m in diameter would be created to produce the seismic waves, which reverberated round the planet for six hours. The survey of satellite images from five different orbiters concluded that the event was not the result of an impact event. [19]
Despite the drawbacks of significant wind interference, on Sol 80 of the Viking 2 lander's mission (roughly November 23, 1976), the on-board seismometer detected an unusual acceleration event during a period of relatively low wind speed. Based on the features of the signal and assuming Mars's crust behaves similar to Earth's crust near the lander's testing site in Southern California, the event was estimated to have a Richter magnitude of 2.7 at a distance of roughly 110 kilometers. [2] However, the wind speed was only measured 20 minutes previously, and 45 minutes after, at 2.6 and 3.6 meters per second, respectively. While a sudden wind gust of 16 m/s would have been required to produce the event, it could not be completely ruled out. [20] The Sol 80 event was later identified as a marsquake. [4] The earlier Sol 53 event initially received much interest as a possible marsquake, but was correlated with wind and not considered further. [2] Following the re-evaluation of the Sol 80 event as a marsquake, a re-evaluation of the Sol 53 event showed that it was unique among all Viking daytime recorded waveforms and the only one with a waveform with a rapid rise time and duration similar to Sol 80. Consequently Sol 53 was identified as a marsquake. Comparing Viking with InSight events, using technologies 43 years apart is challenging, but comparison of the two Viking events with some InSight events showed that the similarity of waveforms was reasonable. [4]
On Sol 128 of the InSight lander mission the Seismic Experiment for Interior Structure (SEIS) detected one magnitude 1–2 seismic event on April 6, 2019. [21] Three other unconfirmed candidate seismic events were detected on March 14, April 10 and April 11, 2019. The quake is similar to moonquakes detected during the Apollo program. It could have been caused by activity internal to the planet or by a meteorite striking the surface. The epicenter was believed to be within 100 km of the lander. As of 30 September 2019, SEIS had reported 450 events of various types. [22]
NASA's Mars Perseverance Rover will act as a seismic source of known temporal and spatial localization as it lands on the surface. The InSight lander will evaluate whether the signals produced by this event will be detectable by 3,452 km away. [23]
Viking 1 was the first of two spacecraft, along with Viking 2, each consisting of an orbiter and a lander, sent to Mars as part of NASA's Viking program. The lander touched down on Mars on July 20, 1976, the first successful Mars lander in history. Viking 1 operated on Mars for 2,307 days or 2245 Martian solar days, the longest extraterrestrial surface mission until the record was broken by the Opportunity rover on May 19, 2010.
Meridiani Planum (alternatively Terra Meridiani) is a large plain straddling the equator of Mars. The plain sits on top of an enormous body of sediments that contains bound water. The iron oxide in the spherules is crystalline (grey) hematite (Fe2O3).
The possibility of life on Mars is a subject of interest in astrobiology due to the planet's proximity and similarities to Earth. To date, no conclusive evidence of past or present life has been found on Mars. Cumulative evidence suggests that during the ancient Noachian time period, the surface environment of Mars had liquid water and may have been habitable for microorganisms, but habitable conditions do not necessarily indicate life.
A transit of Phobos across the Sun as seen from Mars takes place when Phobos passes directly between the Sun and a point on the surface of Mars, obscuring a large part of the Sun's disc for an observer on Mars. During a transit, Phobos can be seen from Mars as a large black disc rapidly moving across the face of the Sun. At the same time, the shadow (antumbra) of Phobos moves across the Martian surface.
Martian spherules (also known as hematite spherules, blueberries, & Martian blueberries) are small spherules (roughly spherical pebbles) that are rich in an iron oxide (grey hematite, α-Fe2O3) and are found at Meridiani Planum (a large plain on Mars) in exceedingly large numbers.
In 1976 two identical Viking program landers each carried four types of biological experiments to the surface of Mars. The first successful Mars landers, Viking 1 and Viking 2, then carried out experiments to look for biosignatures of microbial life on Mars. The landers each used a robotic arm to pick up and place soil samples into sealed test containers on the craft.
Elysium, located in the Elysium and Cebrenia quadrangles, is the second largest volcanic region on Mars, after Tharsis. The region includes the volcanoes Hecates Tholus, Elysium Mons and Albor Tholus. The province is centered roughly on Elysium Mons at 24.7°N 150°E. Elysium Planitia is a broad plain to the south of Elysium, centered at 3.0°N 154.7°E. Another large volcano, Apollinaris Mons, lies south of Elysium Planitia and is not part of the province. Besides having large volcanoes, Elysium has several areas with long trenches, called fossa or fossae (plural) on Mars. They include the Cerberus Fossae, Elysium Fossae, Galaxias Fossae, Hephaestus Fossae, Hyblaeus Fossae, Stygis Fossae and Zephyrus Fossae.
A quake is the result when the surface of a planet, moon or star begins to shake, usually as the consequence of a sudden release of energy transmitted as seismic waves, and potentially with great violence. The types of quakes include earthquake, moonquake, marsquake, venusquake, sunquake, starquake, and mercuryquake. They can also all be referred to generically as earthquakes.
The climate of Mars has been a topic of scientific curiosity for centuries, in part because it is the only terrestrial planet whose surface can be easily directly observed in detail from the Earth with help from a telescope.
The Cerberus Fossae are a series of semi-parallel fissures on Mars formed by faults which pulled the crust apart in the Cerberus region. They are 1235 km across and centered at 11.28 °N and 166.37 °E. Their northernmost latitude is 16.16 °N and their southernmost latitude 6.23 °N. Their easternmost and westernmost longitudes are 174.72 °E and 154.43 °E, respectively. They can be seen in the Elysium quadrangle.
Mars is the fourth planet from the Sun. The surface of Mars is orange-red because it is covered in iron(III) oxide dust, giving it the nickname "the Red Planet". Mars is among the brightest objects in Earth's sky, and its high-contrast albedo features have made it a common subject for telescope viewing. It is classified as a terrestrial planet and is the second smallest of the Solar System's planets with a diameter of 6,779 km (4,212 mi). In terms of orbital motion, a Martian solar day (sol) is equal to 24.5 hours, and a Martian solar year is equal to 1.88 Earth years. Mars has two natural satellites that are small and irregular in shape: Phobos and Deimos.
Almost all water on Mars today exists as polar permafrost ice, though it also exists in small quantities as vapor in the atmosphere.
Lunar seismology is the study of ground motions of the Moon and the events, typically impacts or moonquakes, that excite them.
The Interior Exploration using Seismic Investigations, Geodesy and Heat Transport (InSight) mission was a robotic lander designed to study the deep interior of the planet Mars. It was manufactured by Lockheed Martin Space, was managed by NASA's Jet Propulsion Laboratory (JPL), and two of its three scientific instruments were built by European agencies. The mission launched on 5 May 2018 at 11:05:01 UTC aboard an Atlas V-401 launch vehicle and successfully landed at Elysium Planitia on Mars on 26 November 2018 at 19:52:59 UTC. InSight was active on Mars for 1440 sols.
The Seismic Experiment for Interior Structure (SEIS) is a seismometer and the primary scientific instrument on board the InSight Mars lander launched on 5 May 2018 for a landing on 26 November 2018; the instrument was deployed to the surface of Mars on 19 December. SEIS is expected to provide seismic measurements of marsquakes, enabling researchers to develop 3D structure maps of the deep interior. Better understanding the internal structure of Mars will lead to better understanding of the Earth, Moon, and rocky planetary bodies in general.
Sol is a solar day on Mars; that is, a Mars-day. A sol is the apparent interval between two successive returns of the Sun to the same meridian as seen by an observer on Mars. It is one of several units for timekeeping on Mars.
Temperature and Winds for InSight (TWINS) is a NASA meteorological suite of instruments on board the InSight lander that landed on Mars on 26 November 2018. TWINS provides continuous wind and air temperature measurements to help understand the seismic data from the Seismic Experiment for Interior Structure (SEIS) instrument. The instruments were developed by the Spanish Astrobiology Center at Madrid, Spain.
In modern times, numerous impact events on Mars have been detected. Although most have been inferred from the appearance of new impact craters on the planet, some have corresponded to marsquakes felt by the InSight lander. To date, no impacting meteors have been directly observed as a fireball or discovered in space before impact.
The Passive Seismic Experiment Package (PSEP) was a scientific experiment deployed on the lunar surface by the astronauts of Apollo 11 as part of the Early Apollo Surface Experiments Package (EASEP). The experiment's goal was to determine the structure, tectonic activity, physical nature, and composition of the Moon. PSEP was the first seismometer to be deployed on a planetary body other than Earth.
Seismic velocity structure is the distribution and variation of seismic wave speeds within Earth's and other planetary bodies' subsurface. It is reflective of subsurface properties such as material composition, density, porosity, and temperature. Geophysicists rely on the analysis and interpretation of the velocity structure to develop refined models of the subsurface geology, which are essential in resource exploration, earthquake seismology, and advancing our understanding of Earth's geological development.