Seismic detection of the martian core

Clues to a planet’s geologic history are contained in its interior structure, particularly its core. We detected reflections of seismic waves from the core-mantle boundary of Mars using InSight seismic data and inverted these together with geodetic data to constrain the radius of the liquid metal core to 1830 ± 40 kilometers. The large core implies a martian mantle mineralogically similar to the terrestrial upper mantle and transition zone but differing from Earth by not having a bridgmanite-dominated lower mantle. We inferred a mean core density of 5.7 to 6.3 grams per cubic centimeter, which requires a substantial complement of light elements dissolved in the iron-nickel core. The seismic core shadow as seen from InSight’s location covers half the surface of Mars, including the majority of potentially active regions—e.g., Tharsis—possibly limiting the number of detectable marsquakes.

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Reconstruction of the Reservoir Fine Structure by Using Scattering Attributes

10.2118/206083-ms ◽

2021 ◽

Author(s):

Vladimir Cheverda ◽

Vadim Lisitsa ◽

Maksim Protasov ◽

Galina Reshetova ◽

Andrey Ledyaev ◽

...

Keyword(s):

Seismic Data ◽

Numerical Experiments ◽

Seismic Waves ◽

Fractured Reservoirs ◽

Three Dimensional ◽

Geological Structure ◽

Discrete Elements ◽

Digital Twin ◽

The North ◽

Slip Surfaces

Abstract To develop the optimal strategy for developing a hydrocarbon field, one should know in fine detail its geological structure. More and more attention has been paid to cavernous-fractured reservoirs within the carbonate environment in the last decades. This article presents a technology for three-dimensional computing images of such reservoirs using scattered seismic waves. To verify it, we built a particular synthetic model, a digital twin of one of the licensed objects in the north of Eastern Siberia. One distinctive feature of this digital twin is the representation of faults not as some ideal slip surfaces but as three-dimensional geological bodies filled with tectonic breccias. To simulate such breccias and the geometry of these bodies, we performed a series of numerical experiments based on the discrete elements technique. The purpose of these experiments is the simulation of the geomechanical processes of fault formation. For the digital twin constructed, we performed full-scale 3D seismic modeling, which made it possible to conduct fully controlled numerical experiments on the construction of wave images and, on this basis, to propose an optimal seismic data processing graph.

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Study on Seismic Detection Applied in Mine Advance and Side

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.580-583.1649 ◽

2014 ◽

Vol 580-583 ◽

pp. 1649-1652

Author(s):

Yun Bing Hu ◽

Yao Wang ◽

Yan Qing Wu ◽

Zi Xuan Liu

Keyword(s):

Seismic Data ◽

Mine Field ◽

Qinshui Basin ◽

Radon Transformation ◽

Hazard Detection ◽

Seismic Detection

This paper mainly discusses that the tunnel seismic advance detection is applied in mine geo-hazard detection. Separating the field seismic data of mine by radon transformation and migrating the data through advance way and side way, we accomplished advance and side detection simultaneously by one-time shot seismic data. Case study was carried on at Qinshui basin Yangmei No.5 mine field, and detection results mainly coincide with out-crops, demonstrating that our method can be one reference in mine geo-hazard detection.

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Estimation of absolute stress in the hypocentral region of the 2019 Ridgecrest, California, earthquakes

10.21203/rs.3.rs-75177/v1 ◽

2020 ◽

Author(s):

Yuri Fialko

Keyword(s):

Seismic Data ◽

Plate Tectonics ◽

Active Faults ◽

Active Regions ◽

Seismogenic Zone ◽

Shear Stresses ◽

Strong Earthquakes ◽

Frictional Strength ◽

Tectonically Active ◽

Weak Fault

Abstract Strength of the upper brittle part of the Earth's lithosphere controls deformation styles in tectonically active regions, surface topography, seismicity, and the occurrence of plate tectonics, yet it remains one of the least constrained and most debated quantities in geophysics. Seismic data (in particular, earthquake focal mechanisms) have been used to infer orientation of the principal stress axes. Here I show that the focal mechanism data can be combined with information from precise earthquake locations to place robust constraints not only on the orientation, but also on the magnitude of absolute stress at depth. The proposed method uses machine learning to identify quasi-linear clusters of seismicity associated with active faults. A distribution of the relative attitudes of conjugate faults carries information about the amplitude and spatial heterogeneity of the deviatoric stress and frictional strength in the seismogenic zone. The observed diversity of dihedral angles between conjugate faults in the Ridgecrest (California, USA) area that hosted a recent sequence of strong earthquakes suggests the effective coefficient of friction of 0.4-0.6, and depth-averaged shear stresses on the order of 25-40 MPa, intermediate between predictions of the "strong" and "weak" fault theories.

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Numerical modelling of recent impacts on Mars and contribution to InSight mission science

10.5194/epsc2021-459 ◽

2021 ◽

Author(s):

Katarina Miljkovic ◽

Andrea Rajsic ◽

Tanja Neidhart ◽

Eleanor Sansom ◽

Natalia Wojcicka ◽

...

Keyword(s):

Seismic Data ◽

Seismic Energy ◽

Climate Impact ◽

Geochemical Evolution ◽

Mantle Flow ◽

Crater Formation ◽

Geologic History ◽

The One ◽

The Impact ◽

Insight Mission

The crust on Mars has been structurally affected by various geologic processes such as impacts, volcanism, mantle flow and erosion. Previous observations and modelling point to a dynamically active interior in early Martian history, that for some reason was followed by a rapid drop in heat transport. Such a change has significantly influenced the geological, geophysical and geochemical evolution of the planet, including the history of water and climate. Impact-induced seismic signature is dependent on the target properties (conditions in the planetary crust and interior) at the time of crater formation; Thus, we can use simulations of impact cratering mechanics as a tool to probe the interior properties of a planet.Contrary to large impacts happening in Mars&#8217; early geologic history, the present-day impact bombardment is limited to small meter-size crater-forming impacts (in the atmosphere and on the ground), which are also natural seismic sources (Daubar et al., 2018, 2020; Neidhart et al., 2020). Impact simulations, in tandem with NASA InSight seismic observations (Benerdt et al., 2020, Giardini et al., 2020), can help understand the crustal properties over the course of Mars&#8217; evolution, including the state of Mars&#8217; crust today. Our most recent numerical investigations include: estimating the seismic efficiency and moment from small meter-size impact events, tracking pressure propagation from the impact point into far field, transfer of impact energy into seismic energy, etc (Rajsic et al., 2020, Wojcicka et al., 2020). Understanding coupling between impact crater formation process with the generation and progression of seismic energy can help identify small impact everts in seismic data on Mars. We also looked at the same process on the Earth (Neidhart et al., 2020) and the Moon (Rajsic, et al., this issue).Since the landing of the NASA InSight mission on Mars, there was a dozen known new impacts (Miljkovic et al., 2021). However, all but one impact occurred much too far away (3000 to 8400 km distance from the InSight lander) to be within the detectability threshold estimates (Teanby et al., 2015; Wojcicka et al., 2020). About 50% of the observed craters were likely single impacts and the other 50% were evidently cluster craters with less than 40 individual craters in the largest cluster. The largest single crater was ~14 m in diameter, and the largest crater in a cluster was ~13 m (Neidhart et al., this issue), consistent with crater cluster observations (Daubar et al., 2013). The one impact that had a possibility of being detected by SEIS was 1.5 m in diameter at 37 km distance (Daubar et al. 2020).Considering that orbital imaging is limited in space and time, these known new impacts represent only a fraction of the total number of impacts that have occurred on Mars in the last ~2 years. According to impact flux calculations (Teanby and Wookey, 2011), there should have been ~3000 detectable craters, larger than 1 m in diameter, formed on Mars since InSight landed. If any of these unobserved impacts have been large enough and close enough to InSight to detect seismically, we have not yet discerned them in the seismic data.References:Banerdt, W.B. et al. (2020) Nature Geosci. 13, 183-189.Giardini, D. et al. (2020) Nature Geosci. 13, 205-212.Daubar, I.J. et al. (2020) J. Geophys. Res. Planets, 125: e2020JE006382.W&#243;jcicka, N. et al. (2020) J. Geophys. Res. Planets, 125, e2020JE006540.Raj&#353;i&#263; et al. (2021) J. Geophys. Res. Planets, 126, e2020JE006662.Daubar et al. (2013) Icarus 225, 506-516.Teanby, N.A. & Wookey, J. (2011) PEPI 186, 70-80.Neidhart, T. et al. (2020) PASA, 38, E016.Teanby, N.A. et al. (2015) Icarus 256, 46-62.Miljkovic, K. et al. (2021) LPSC, LPI Contribution No. 1758.

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Fault whispers: Transmission distortions on prestack seismic reflection data

Geophysics ◽

10.1190/1.1444733 ◽

2000 ◽

Vol 65 (2) ◽

pp. 377-389 ◽

Cited By ~ 21

Author(s):

Paul J. Hatchell

Keyword(s):

Seismic Data ◽

Seismic Waves ◽

Shallow Gas ◽

Seismic Reflection Data ◽

Reflection Data ◽

Amplitude Versus Offset ◽

Velocity Changes ◽

Transmission Distortions ◽

Amplitude Versus ◽

Buried Faults

Transmission distortions are observed on prestack seismic data at two locations in the Gulf of Mexico. These distortions produce anomalous amplitude versus offset (AVO) signatures. The locations of the distortion zones are determined using acquisition geometry and ray tracing. No obvious reflection events, such as shallow gas zones, are observed at the predicted locations of the distortion zones. Instead, the distortion zones correlate with buried faults and unconformities. It is postulated that the distortions are produced by velocity changes across buried faults and unconformities. The distortions result from an interference pattern resulting from seismic waves arriving from different sides of the faults. A simple model is developed to explain many of the characteristics of the distortion pattern.

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Sequencing seismograms: A panoptic view of scattering in the core-mantle boundary region

Science ◽

10.1126/science.aba8972 ◽

2020 ◽

Vol 368 (6496) ◽

pp. 1223-1228 ◽

Cited By ~ 3

Author(s):

D. Kim ◽

V. Lekić ◽

B. Ménard ◽

D. Baron ◽

M. Taghizadeh-Popp

Keyword(s):

Seismic Waves ◽

Learning Algorithm ◽

Three Dimensional ◽

Boundary Region ◽

Marquesas Islands ◽

Mantle Boundary ◽

Core Mantle Boundary ◽

Subsurface Structures ◽

The Core ◽

The Pacific

Scattering of seismic waves can reveal subsurface structures but usually in a piecemeal way focused on specific target areas. We used a manifold learning algorithm called “the Sequencer” to simultaneously analyze thousands of seismograms of waves diffracting along the core-mantle boundary and obtain a panoptic view of scattering across the Pacific region. In nearly half of the diffracting waveforms, we detected seismic waves scattered by three-dimensional structures near the core-mantle boundary. The prevalence of these scattered arrivals shows that the region hosts pervasive lateral heterogeneity. Our analysis revealed loud signals due to a plume root beneath Hawaii and a previously unrecognized ultralow-velocity zone beneath the Marquesas Islands. These observations illustrate how approaches flexible enough to detect robust patterns with little to no user supervision can reveal distinctive insights into the deep Earth.

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Depth filtering for one‐component seismic data

Geophysics ◽

10.1190/1.1443169 ◽

1991 ◽

Vol 56 (9) ◽

pp. 1482-1485 ◽

Cited By ~ 4

Author(s):

Robert Sun ◽

George A. McMechan

Keyword(s):

Seismic Data ◽

Seismic Waves ◽

Downward Continuation ◽

Near Surface ◽

Left Behind ◽

Elastic Data ◽

Ground Roll ◽

The Waves ◽

Seismic Wavefield ◽

Number Of Authors

The concept of downward continuation of a seismic wavefield recorded on the earth’s surface to remove near‐surface effects has previously been applied by a number of authors including Schultz and Sherwood (1980), Berryhill (1979, 1984), and McMechan and Chen (1990). Recently, McMechan and Sun (1991) demonstrated, using synthetic elastic data, that downward continuation of an elastic (two‐component) seismic wavefield separates various seismic waves, based on their depth of propagation. This was used to simultaneously remove direct waves and ground roll. The direct compressional and shear waves and the ground roll get left behind in the near surface during downward continuation; subsequent upward continuation reconstructs the surface‐recorded wavefield without the waves propagating in the shallow layers.

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Seismic detection and interpretation of porosity in Carboniferous age rocks of Kansas and Oklahoma

Geophysics ◽

10.1190/1.1442601 ◽

1989 ◽

Vol 54 (11) ◽

pp. 1371-1383 ◽

Cited By ~ 2

Author(s):

M. R. Thomasson ◽

R. W. Kettle ◽

R. M. Lloyd ◽

R. K. McCormack ◽

J. P. Lindsey

Keyword(s):

Seismic Data ◽

Acoustic Properties ◽

Reservoir Quality ◽

Seismic Modeling ◽

Work Station ◽

South Central ◽

Seismic Detection ◽

Seismic Sections

Many large Mississippian fields (5–130 MMBO) in south‐central Kansas and northern Oklahoma produce from discrete pods of porous chert and dolomite called “chat.” Chat has unusual acoustic properties that allow the porosity pods to be recognized on seismic sections. Integrated geologic and geophysical studies of two analog fields indicate that both reservoir quality and geometry can be interpreted from good quality seismic data. Seismic modeling on an interactive work station plays an important role in developing these interpretations.

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Seismic complex ray tracing in 2D/3D viscoelastic anisotropic media by a modified shortest-path method

Geophysics ◽

10.1190/geo2020-0113.1 ◽

2020 ◽

Vol 85 (6) ◽

pp. T331-T342

Author(s):

Xing-Wang Li ◽

Bing Zhou ◽

Chao-Ying Bai ◽

Jian-Lu Wu

Keyword(s):

Ray Tracing ◽

Shortest Path ◽

Anisotropic Medium ◽

Wave Energy ◽

Seismic Data ◽

Seismic Waves ◽

Effective Means ◽

Anisotropic Media ◽

The Real ◽

Complex Ray

In a viscoelastic anisotropic medium, velocity anisotropy and wave energy attenuation occur and are often observed in seismic data applications. Numerical investigation of seismic wave propagation in complex viscoelastic anisotropic media is very helpful in understanding seismic data and reconstructing subsurface structures. Seismic ray tracing is an effective means to study the propagation characteristics of high-frequency seismic waves. Unfortunately, most seismic ray-tracing methods and traveltime tomographic inversion algorithms only deal with elastic media and ignore the effect of viscoelasticity on the seismic raypath. We have developed a method to find the complex ray velocity that gives the seismic ray speed and attenuation in an arbitrary viscoelastic anisotropic medium, and we incorporate them with the modified shortest-path method to determine the raypath and calculate the real and imaginary traveltime (wave energy attenuation) simultaneously. We determine that the complex ray-tracing method is applicable to arbitrary 2D/3D viscoelastic anisotropic media in a complex geologic model and the computational errors of the real and imaginary traveltime are less than 0.36% and 0.59%, respectively. The numerical examples verify that the new method is an effective and powerful tool for accomplishing seismic complex ray tracing in heterogeneous viscoelastic anisotropic media.

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