Seismic velocity structure

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The velocity structure of the Earth. The red line is the P-wave velocity, the blue line is the S-wave velocity, and the green line density. (Data was adopted from the RockHound Python library.) Velocity Structure of Earth.svg
The velocity structure of the Earth. The red line is the P-wave velocity, the blue line is the S-wave velocity, and the green line density. (Data was adopted from the RockHound Python library.)

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. [1] 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. [2]

Contents

History

The understanding of the Earth's seismic velocity structure has developed significantly since the advent of modern seismology. The invention of the seismogram in the 19th-century catalyzed the systematic study of seismic velocity structure by enabling the recording and analysis of seismic waves. [3]

20th century

The distribution of Global Seismographic Network stations. The map is generated by Python using Cartopy, data was adopted from the United States Geological Survey (USGS). Map of Global Seismic Network Stations.svg
The distribution of Global Seismographic Network stations. The map is generated by Python using Cartopy, data was adopted from the United States Geological Survey (USGS).

The field of seismology achieved significant breakthroughs in the 20th century.In 1909, Andrija Mohorovičić identified a significant boundary within the Earth known as the Mohorovičić discontinuity, which demarcates the transition between the Earth's crust and mantle with a notable increase in seismic wave speeds. [5] This work was furthered by Beno Gutenberg, who identified the boundary at the core-mantle layer in the early to mid-20th century. [6] The 1960s introduction of the World Wide Standardized Seismograph Network dramatically improved the collection and understanding of seismic data, contributing to the broader acceptance of plate tectonics theory by illustrating variations in seismic velocities. [7] [8] [1]

Later, seismic tomography, a technique used to create detailed images of the Earth's interior by analyzing seismic waves, was propelled by the contributions of Keiiti Aki and Adam Dziewonski in the 1970s and 1980s, enabling a deeper understanding of the Earth's velocity structure. [9] [10] [11] Their work laid the foundation for the Preliminary Reference Earth Model in 1981, a significant step toward modeling the Earth's internal velocities. [1] [12] The establishment of the Global Seismic Network in 1984 by Incorporated Research Institutions for Seismology further enhanced seismic monitoring capabilities, continuing the legacy of the WWSSN. [13]

21st century

The advancement in seismic tomography and the expansion of the Global Seismic Network, alongside greater computational power, have enabled more accurate modeling of the Earth's internal velocity structure. [14] [15] Recent progress focuses on the inner core's velocity features [16] and applying methods like ambient noise tomography for improved imaging. [17]

Principle of seismic velocity structure

The study of seismic velocity structure, using the principles of seismic wave propagation, offers critical insights into the Earth's internal structure, material composition, and physical states. [1] Variations in wave speed, influenced by differences in material density and state (solid, liquid, or gas), alter wave paths through refraction and reflection, as described by Snell's Law. [18] [19] P-waves, which can move through all states of matter and provide data on a range of depths, change speed based on the material's properties, such as type, density, and temperature. [3] [1] S-waves, in contrast, are constrained to solids and reveal information about the Earth's rigidity and internal composition, including the discovery of the outer core's liquid state since they cannot pass through it. [3] The study of these waves' travel times and reflections offers a reconstructive view of the Earth's layered velocity structure. [20]

This is an illustration of Snell's Law. A seismic wave coming with the path of the red line would refract when it passes through the surface of medium change. Seismic waves travelling at a critical angle (blue line) will be refracted critically with an angle of refraction equal to 90deg. Snell's law 13 Nov 2023.svg
This is an illustration of Snell's Law. A seismic wave coming with the path of the red line would refract when it passes through the surface of medium change. Seismic waves travelling at a critical angle (blue line) will be refracted critically with an angle of refraction equal to 90°.
An illustration of seismic reflection and refraction. Seismic refraction usually requires a wide incident angle so that the refracted seismic wave can travel critically (angle of refraction equals 90deg). Seismic Refraction and Reflection.svg
An illustration of seismic reflection and refraction. Seismic refraction usually requires a wide incident angle so that the refracted seismic wave can travel critically (angle of refraction equals 90°).

Average velocity structure of planetary bodies

LayerEarthMoonMars
CrustP-wave: 6.0–7.0 km/s (continental) [12]

P-wave: 5.0–7.0 km/s (oceanic) [12]

S-wave: 3.5–4.0 km/s [12]

P-wave: 5.1–6.8 km/s [21]

S-wave: 2.96–3.9 km/s [21]

P-wave: 3.5–5 km/s [22]

S-wave: 2–3 km/s [23] [22]

MantleUpper Mantle:

P-wave: 7.5–8.5 km/s [12]

S-wave: 4.5–5.0 km/s [12]

P-wave: 7.7 km/s [21]

S-wave: 4.5 km/s [21]

Upper Mantle:

P-wave: 8 km/s [22] [24]

S-wave: 4.5 km/s [22] [24]

Lower Mantle:

P-wave: 10–13 km/s [12]

S-wave: 5.5–7.0 km/s [12]

Lower Mantle:

P-wave: 5.5 km/s [25]

S-waves: Not applicable (liquid) [25]

CoreOuter Core:

P-wave: 8.0–10 km/s [12]

S-waves: Not applicable (liquid)

Outer core:

P-wave: 4 km/s [26] [27]

S-waves: Not applicable (liquid) [28] [27]

P-wave: 5 km/s [29]

S-waves: Not applicable (liquid) [29]

Inner Core:

P-wave: ~11 km/s [12]

S-wave: ~3.5 km/s [12]

Inner core:

P-wave: 4.4 km/s [27]

S-wave: 2.4 km/s [27]

Velocity structure of Earth

The internal structural of the Earth. Earth internal structure.svg
The internal structural of the Earth.

Seismic waves traverse the Earth's layers at speeds that differ according to each layer's unique properties, with their velocities shaped by the respective temperature, composition, and pressure. [1] The Earth's structure features distinct seismic discontinuities where these velocities shift abruptly, signifying changes in mineral composition or physical state. [30]

Crust

Within the Earth's crust, seismic velocities increase with depth, mainly due to rising pressure, which makes materials denser. [31] The relationship between crustal depth and pressure is direct; as the overlying rock exerts weight, it compacts underlying layers, reduces rock porosity, increases density, and can alter crystalline structures, thus accelerating seismic waves. [32]

Crustal composition varies, affecting seismic velocities. The upper crust typically contains sedimentary rocks with lower velocities (2.0–5.5 km/s), while the lower crust consists of denser basaltic and gabbroic rocks, leading to higher velocities. [33]

Although geothermal gradient, which refers to the increase in temperature with depth in the Earth's interior, can decrease seismic velocities, this effect is usually outweighed by the velocity-boosting impact of increased pressure. [34]

The 1-dimensional velocity structure of the Earth, grey area indicating the transition zone. The change in velocity at the core-mantle boundary (CMB) represents changes in physical state from solid to fluid. At the inner-core boundary (ICB), the core changes from fluid to solid as reflected by the increase in velocity. Earth velocity structure with internal structure.svg
The 1-dimensional velocity structure of the Earth, grey area indicating the transition zone. The change in velocity at the core-mantle boundary (CMB) represents changes in physical state from solid to fluid. At the inner-core boundary (ICB), the core changes from fluid to solid as reflected by the increase in velocity.

Upper mantle

Seismic velocity in the upper mantle rises primarily due to increased pressure, similar to the crust but with a more pronounced effect on velocity. [3] Additionally, pressure-induced mineral phase changes, where minerals rearrange their structures, in the upper mantle contribute to this acceleration. [35] For example, olivine transforms into its denser polymorphs, wadsleyite and ringwoodite, at depths of approximately 410 km and 660 km respectively, resulting in a more compact structure that facilitates faster seismic wave propagation in the transition zone. [35]

Lower mantle

In the lower mantle, the rise in seismic velocity is driven by increasing pressure, which is greater here than in the upper layers, resulting in denser rock and faster seismic wave travel. [36] Although thermal effects may lessen seismic velocity by softening the rock, the predominant factor in the lower mantle remains the increase in pressure. [34] [37]

Outer Core

In the outer core, seismic velocity significantly decreases due to its liquid state, which impedes the speed of seismic waves despite the high pressure. This sharp decline is observed at the core-mantle boundary, also referred to as the D'' region or Gutenberg discontinuity. [12]

Furthermore, the reduction in seismic velocity in the outer core suggests the presence of lighter elements like oxygen, silicon, sulfur, and hydrogen, which lower the density of the outer core. [38] [39] [40] [41]

Illustration of the proposed "inner" inner core. Seismic wave propagation in the red line (along the rotational axis) is faster than that in the blue line (along the equatorial axis). The inner inner core.svg
Illustration of the proposed "inner" inner core. Seismic wave propagation in the red line (along the rotational axis) is faster than that in the blue line (along the equatorial axis).

Inner core

The solid, high-density composition of the inner core, predominantly iron and nickel, results in increased seismic velocity compared to the liquid outer core. [44] While light elements also present in the inner core modulate this velocity, their impact is relatively contained. [45]

Anisotropy of inner core

The inner core is anisotropic, causing seismic waves to vary in speed depending on their direction of travel. P-waves, in particular, move more quickly along the inner core's rotational axis than across the equatorial plane. [42] This suggests that Earth's rotation affects the alignment of iron crystals during the core's solidification. [46]

There is also evidence suggesting a distinct transition zone ("inner" inner core), with a hypothesized transition zone some 250 to 400 km beneath the inner core boundary (ICB). This is inferred from anomalies in travel times for P-wave that travels through the inner core. [42] [43] This transition zone, perhaps 100 to 200 km thick, may provide insights into the alignment of iron crystals, the distribution of light elements, or Earth's accretion history. [42] [43]

Studying the inner core poses significant challenges for seismologists and geophysicists, given that it accounts for less than 1% of Earth's volume and is difficult for seismic waves to penetrate. [16] [43] Moreover, S-wave detection is challenging due to minimal compressional-shear wave conversion at the boundary and substantial attenuation within the inner core, leaving S-wave velocity uncertain and an area for future research. [3] [16]

Lateral variation of velocity structure

Lateral variation in seismic velocity is a horizontal change in seismic wave speeds across the Earth's crust due to differences in geological structures like rock types, temperature, and fluids presence, affecting seismic wave travel speed. [47] This variation helps delineate tectonic plates and geological features and is key to resource exploration and understanding the Earth's internal heat flow. [48]

Discontinuity

Discontinuities are zones or surfaces within the Earth that lead to abrupt changes in seismic velocity, revealing the composition and demarcating the boundaries between the Earth's layers. [3]

The following are key discontinuities within the Earth:

Velocity structure of the Moon

Location of Lunar seismometer. A total of five PSE were placed on the Moon, while PSE from Apollo 11 stopped functioning shortly after deployment. Location of Lunar Seismometers.png
Location of Lunar seismometer. A total of five PSE were placed on the Moon, while PSE from Apollo 11 stopped functioning shortly after deployment.

Knowledge of the Moon's seismic velocity primarily stems from seismic records obtained by Apollo missions' Passive Seismic Experiment (PSE) stations. [50] Between 1969 and 1972, five PSE stations were deployed on the lunar surface, with four operational until 1977. [50] These four stations created a network on the near side of the moon, configured as an equilateral triangle with two stations at one vertex. [51] This network recorded over 13,000 seismic events, and the gathered data remains a subject of ongoing study. [50] [51] The analysis has revealed four moonquake mechanisms: shallow, deep, thermal, and those caused by meteoroid impacts. [52]

Crust

The seismic velocity on the Moon varies within its roughly 60 km thick crust, presenting a low seismic velocity at the surface. [53] Velocity readings increase from 100 m/s near the surface to 4 km/s at a depth of 5 km and rise to 6 km/s at 25 km depth. [54] [55] At 25 km depth, a discontinuity presence, at which the seismic velocity increases abruptly to 7 km/s. [55] This velocity then stabilizes, reflecting the consistent composition and hydrostatic pressure conditions at greater depths. [55]

Seismic velocities within the Moon's approximately 60 km thick crust exhibit an initial low of 100 m/s at the surface, [53] which escalates to 4 km/s at 5 km depth, and then to 6 km/s at 25 km depth where velocities sharply increase to 7 km/s and stabilize, revealing a consistent composition and pressure conditions in deeper layers. [54] [55]

Surface velocities are low due to the loose, porous nature of the regolith. [54] Deeper, compaction increases velocities, with the region beyond 25 km depth characterized by dense, sealed anorthosite and gabbro layers, suggesting a crust with hydrostatic pressure. [55] The Moon's geothermal gradient minimally reduces velocities by 0.1-0.2 km/s. [55]

The 1-Dimensional velocity structure of the Moon. The changes in velocity represent changes in physical state or lunar composition. The red line is S-wave velocity, while blue line is P-wave velocity. 1D velocity structure of the Moon.png
The 1-Dimensional velocity structure of the Moon. The changes in velocity represent changes in physical state or lunar composition. The red line is S-wave velocity, while blue line is P-wave velocity.

Mantle

Research into the seismic structure of the Moon's mantle is hampered by the scarcity of data. Analysis of moonquake waveforms suggests that seismic wave velocities in the upper mantle (ranging from 60 to 400 km in depth) exhibit a minor negative gradient, with S-wave speeds decreasing at rates between -6×10−4 to -13×10−4 km/s per kilometer. [21] A decease in P-wave velocities has also been postulated. [57] The data delineates a transition zone between 400 km and 480 km depth, where a noticeable decrement in the velocities of both P- and S-waves occurs. [21]

Uncertainty grows when probing the lower mantle, extending from 480 km to 1100 km beneath the lunar surface. Some studies detect a consistent decline in S-wave transmission, suggesting absorption or scattering phenomena, [21] while other findings indicate that velocities for P- and S-waves may in fact rise. [57] [58]

Temperature increases with depth are believed to be the primary influence behind the observed drop in velocities within the upper mantle, suggesting a mantle heavily regulated by thermal gradients rather than compositional changes. [21] The delineated transition zone implies a division between the chemically distinct upper and lower mantles, possibly explained by an uptick in iron concentration due to high pressure and thermal conditions at depth. [21]

Deeper into the lower mantle, the debate over seismic characteristics continues, with theories of partial melting around the 1000 km depth mark to justify the attenuation of S-wave velocities. [21] [57] This molten state may cause a segregation of materials, resulting in a concentration of magnesium-rich olivine in the lower regions and potentially affecting seismic speeds. [57]

Core

Schematic cross-section of the Moon. The liquid and the partially molten material might be aspherical. Moon cross section.png
Schematic cross-section of the Moon. The liquid and the partially molten material might be aspherical.

Understanding the seismic velocities within the Moon's core presents challenges due to the limited data available. [26]

Outer core:

Inner core:

The sharp decline in P-wave velocity at the mantle-core boundary suggests a liquid outer core, transitioning from 7.7 km/s in the mantle to 4 km/s in the outer core. [59] The inability of S-waves to traverse this zone further confirms its fluid nature with molten iron sulphate. [60]

An increase in seismic velocities upon reaching the inner core intimates a transition to a solid phase. [27] The presence of solid iron-nickel alloys, potentially alloyed with lighter elements, is deduced from this increase. [27]

Current geophysical models posit a relatively diminutive Lunar core, with the liquid outer core accounting for 1-3% of the Moon's total mass and the entire core constituting about 15-25% of the lunar mass. [56] [59] While some lunar models suggest the possibility of a core, its existence and characteristics are not unequivocally required by the observed data. [21]

Lateral variation of seismic velocity structure

Crustal velocity also varies laterally, particularly in impact basins, where meteoroid collisions have compacted the substrate, resulting in higher velocities due to reduced porosity.

Lateral variations in the Moon's seismic velocity structure are marked by differences in the crust's physical properties, especially within impact basins. [61] The velocity increases in these regions are attributed to meteoroid impacts, which have compacted the lunar substrate, thereby increasing its density and reducing porosity. [61] This phenomenon has been studied using seismic data from lunar missions, which show that the Moon's crustal structure varies significantly with location, reflecting its complex impact history and internal processes. [57]

Velocity structure of Mars

The 1-Dimensional velocity structure of Mars. The changes in velocity represent changes in physical state or Martian composition. Velocity Structure of Mars.png
The 1-Dimensional velocity structure of Mars. The changes in velocity represent changes in physical state or Martian composition.

The investigation into Mars's seismic velocity has primarily relied on models and the data gathered by the InSight mission, which landed on the planet in 2018. By September 30, 2019, InSight had detected 174 seismic events. [62] Before InSight, the Viking 2 lander attempted to collect seismic data in the 1970s, but it captured only a limited number of local events, which did not yield conclusive insights. [63]

Crust

The crust of Mars, ranging from 10 to 50 km in thickness, exhibits increasing seismic velocity as depth increases, attributable to rising pressure. [64] The upper crust is characterized by low density and high porosity, leading to reduced seismic velocity. [23] Two key discontinuities have been observed: one within the crust at a depth of 5 to 10 km, [65] and another which is likely the crust-mantle boundary, occurring at a depth of 30 to 50 km. [22]

Mantle

Upper mantle:

Lower mantle:

An illustration of the Internal structure of Mars. The core is hypothesised to be liquid. Mars Internal Structure 2.png
An illustration of the Internal structure of Mars. The core is hypothesised to be liquid.

The Martian mantle, composed of iron-rich rocks, facilitates the transmission of seismic waves at high speeds. [64] Research indicates a variation in seismic velocities between depths of 400 and 600 km, where S-wave speeds decrease while P-wave speeds remain constant or increase slightly. [22] This region is known as the Low Velocity Zone (LVZ) in the Martian upper mantle and may be caused by a static layer overlying a convective mantle. [29] The reduction in velocity at the LVZ is likely due to high temperatures and moderate pressures. [22]

Martian mantle research has also identified two discontinuities at depths of approximately 1100 km and 1400 km. These discontinuities suggest phase transitions from olivine to wadsleyite and from wadsleyite to ringwoodite, analogous to the Earth's mantle phase changes at depths of 410 km and 660 km. [29] However, Mars's mantle composition differs from Earth's as it does not have a lower mantle predominated by bridgmanite. [24]

Recent study suggested the presence of a molten lower mantle layer in the Mars which could significantly affect the interpretation of seismic data and our understanding of the planet's thermal history. [25]

Core

Scientific evidence suggests that Mars has a substantial liquid core, inferred from S-wave transmission patterns that indicate these waves do not pass through liquid. [24] The core is likely composed of iron and nickel with a significant proportion of lighter elements, inferred from its lower-than-expected density. [24]

The presence of a solid inner core on Mars, comparable to Earth's, is currently the subject of scientific debate. No definitive evidence has yet confirmed the nature of the inner core, leaving its existence and characteristics as topics for further research. [66]

Lateral variation of velocity structure

Lateral variations in the seismic velocity structure of Mars have been revealed by data from the InSight mission, indicating an intricately layered subsurface. InSight's seismic experiments suggest that these variations reflect differences in crustal thickness and composition, potentially caused by volcanic and tectonic processes unique to Mars. Such variations also provide evidence for the presence of a liquid layer above the core, suggesting a complex interplay of thermal and compositional factors affecting the planet's evolution. [62] Further analysis of marsquake data may illuminate the relationship between these lateral variations and the Martian mantle's convective dynamics. [67] [65]

Velocity structure of Enceladus

Research on Enceladus's subsurface composition has provided theoretical velocity profiles in anticipation of future exploratory missions. [68] While Enceladus's interior is poorly understood, scientists agree on a general structure consisting of an outer icy shell, a subsurface ocean, and a rocky core. [69] [70] In a recent study, three models—single core, [71] thick ice, [72] and layered core [73] —were proposed to delineate Enceladus' internal characteristics. [68]

According to these models, seismic velocities are expected to decrease from the ice shell to the ocean, reflecting transitions from porous, fractured ice to a more fluid state. [74] Conversely, velocities are predicted to rise within the solid silicate core, illustrating the stark contrast between the moon's various layers. [68]

The 1-Dimensional velocity structure of three models of Enceladus (reproduced from Dapre and Irving, 2024). Enceladus Velocity Structure.svg
The 1-Dimensional velocity structure of three models of Enceladus (reproduced from Dapré and Irving, 2024).
Internal structure models of Enceladus: Single Core; Thick Ice; and Layered Core Enceladus Internal Structure Models.svg
Internal structure models of Enceladus: Single Core; Thick Ice; and Layered Core

Future plan

Seismic exploration of celestial bodies has so far been limited to the Moon and Mars. However, future space missions are set to extend seismic studies to other entities in our solar system.

The proposed Europa Lander Mission, slated for a launch window between 2025 and 2030, will investigate the seismic activity of Jupiter's moon, Europa. [75] This mission plans to deploy the Seismometer to Investigate Ice and Ocean Structure (SIIOS), an instrument designed by the University of Arizona to withstand Europa's harsh, cold, and radiative environment. [76] [77] SIIOS's goal is to provide insight into Europa's icy crust and subterranean ocean.

In conjunction with its Artemis program to the Moon, NASA has also funded initiatives under the Development and Advancement of Lunar Instrumentation (DALI) program. [78] Among these, the Seismometer for a Lunar Network (SLN) project stands out. The SLN aims to facilitate the creation of a lunar seismometer network by integrating seismometers into future lunar landers or rovers. [79] This initiative is part of NASA's broader effort to prepare for continued exploration of the Moon's geology.

Methods

The study of seismic velocity structure is typically conducted through the observation of seismic data coupled with inverse modeling, which involves adjusting a model based on observed data to infer the properties of the Earth's interior. Here are some methods used to study seismic velocity structure:

Refraction Seismology Seismic refraction is a geophysical method for characterizing subsurface geological features. It operates on the principle that seismic waves—specifically P-waves and S-waves—refract, or bend, when they encounter layers with varying seismic velocities. By analyzing the travel times of these waves as they are refracted at different angles, geophysicists can infer the depth and composition of underlying strata. [80] The technique typically employs man-made seismic sources, such as controlled explosions or the striking of the ground with a sledgehammer, to generate the necessary waves. Despite its utility in providing insights into subsurface structures, seismic refraction has certain limitations. It can be costly to execute, and its resolution is constrained by the wavelength of the seismic waves used, which generally range between 200 m and 1 km. [19]
In refraction seismology, direct wave (blue) arrive the receivers first, followed by headwave (red). The point where the direct wave and headwave meet is known as the crossover point. Refraction 2layers.png
In refraction seismology, direct wave (blue) arrive the receivers first, followed by headwave (red). The point where the direct wave and headwave meet is known as the crossover point.
Reflection Seismology Seismic reflection capitalizes on the echo of seismic waves off boundaries where acoustic impedance varies between earth layers. [81] By recording the differences in travel time and wave amplitude, researchers correlate these measurements with subsurface properties to map out velocity structures, akin to seismic refraction but focusing on wave reflections. [82]
Seismic waves reflected at different boundaries are picked up by receivers at different location. Seismic Reflection Principal.png
Seismic waves reflected at different boundaries are picked up by receivers at different location.
Seismic Tomography Seismic tomography employs the travel times of waves from earthquakes to create three-dimensional subsurface models, revealing variations in seismic velocities linked to material differences, temperature, and composition. [83] [84] Diverging from refraction and reflection methods, which use artificial sources, tomography utilizes natural seismic activity for deeper Earth exploration. This technique is instrumental in investigating geodynamic processes, including mantle convection and plate tectonics. [14]
By analysing seismic waves generated by earthquakes, the velocity structure can be studied which can reflect the subsurface condition where the seismic wave propagated. Seismic tomography.png
By analysing seismic waves generated by earthquakes, the velocity structure can be studied which can reflect the subsurface condition where the seismic wave propagated.
Receiver Function Analysis Receiver function analysis is a seismic method that interprets waveform data to study the conversions and reflections of seismic waves at subsurface interfaces like the Mohorovičić discontinuity. [85] It uses converted S-waves produced when P-waves meet these interfaces to infer depth and seismic properties. [86] Enhanced computing power and extensive seismic networks have advanced this technique, allowing detailed mapping of various geological structures, from sedimentary basin depths to the Mohorovičić discontinuity's topography and beyond. [86] [87]
Different P-wave and S-wave phases are picked up by a receiver for the analysis of velocity structure. Receiver Function Incident Wave.svg
Different P-wave and S-wave phases are picked up by a receiver for the analysis of velocity structure.
Ambient Noise Tomography (ANT) Ambient Noise Tomography is a seismic imaging technique that uses the Earth's background noise, stemming from sources like ocean waves, storms, and traffic, to map its seismic velocity structure. [88] It involves cross-correlating noise records from multiple seismic stations to extract coherent waveforms, akin to those expected from earthquake activity. [89] This process emulates the response recorded if an earthquake had originated at one station and been detected at another, following Green's function for wave propagation. [89] It is particularly effective in delivering high-resolution subsurface images for areas with insufficient seismic events. [90]
Full Waveform Inversion (FWI) Full Waveform Inversion is an iterative method used to fine-tune models of the Earth's subsurface by adjusting them until the synthetic seismograms they produce align with actual observed data. [91] This technique utilizes complete seismic waveforms, not just travel times, enabling scientists to discern more nuanced features in the subsurface. [92] Its application spans from small-scale reservoir imaging, crucial in oil and gas exploration, to larger, regional-scale models for understanding tectonic activity. [93] [94]

Applications of velocity structure

Applications of seismic velocity structure encompass a range of fields where understanding the Earth's subsurface is crucial:

Seismic Imaging and Interpretation Seismic velocity structure analysis enables the generation of subsurface geological imagery, facilitating the identification and characterization of structures like faults and folds. [95] At a larger tectonic scale, it reveals prominent features, including subducting slabs, mantle plumes, and rift zones, thereby providing a comprehensive view of the Earth's internal and plate dynamics. [95]
Resource ExplorationIn the fields of oil, gas, and mineral exploration, knowledge of the seismic velocity structure is vital for discovering reserves and strategizing extraction processes. [82] This understanding helps delineate the size, shape, and physical properties of potential resources, guiding drilling decisions and optimizing recovery. [82]
Earthquake Hazard ManagementThe seismic velocity structure is instrumental in deciphering the propagation of seismic waves during earthquakes. It offers valuable insights into the underlying mechanisms of seismic events, contributing to earthquake hazard assessment and the development of urban planning strategies to mitigate seismic risks. [96]
Volcanology Investigating seismic velocity structures under volcanoes is key to identifying magma chambers and comprehending volcanic formations. [97] This knowledge assists in predicting volcanic activity and assessing potential eruption risks, which is essential for informing hazard preparedness and mitigation efforts. [97]
Engineering Geology and Environmental Geology Seismic velocity structures play a crucial role in construction project site investigations by helping to identify geological features like faults and areas with potentially problematic materials like clay, which can affect the stability and safety of the structures. [98] Additionally, this technique is employed in environmental studies to monitor subsurface contamination and to assess groundwater resources, ensuring sustainable and safe development. [99]
Planetary Geophysics Velocity structure analysis can be applied to other planetary bodies, such as the Moon and Mars, to understand their internal structure and geological history.

Seismic velocity structure analysis extends beyond Earth, applying to other celestial bodies like the Moon and Mars to unravel their internal compositions and geological evolution. [26] This analysis is pivotal in planetary science, providing clues about the formation, tectonic activity, and potential for resources on these extraterrestrial surfaces. [65]

Limitation/Uncertainty

Investigating Earth's inner core through seismic waves presents significant challenges. [1] [16] Directly observing seismic waves that traverses the inner core is difficult due to weak signal conversion at the core boundaries and high attenuation within the core. [1] [16] Recent techniques like earthquake late-coda correlation, which utilises the later part of a seismogram, provide estimates for the inner core's shear wave velocity but are not without challenges. [16]

Seismic velocity studies often assume isotropy, treating Earth's subsurface as having uniform properties in all directions. This simplification is practical for analysis but may not be accurate. [10] [46] The inner core and mantle, for example, likely demonstrate anisotropic, or directionally dependent, properties, which can affect the accuracy of seismic interpretations. [100]

Seismic models are frequently one-dimensional, considering changes in Earth's properties with depth but neglecting lateral variations. [101] Although this method eases computation, it fails to account for the planet's complex three-dimensional structure, potentially misleading our understanding of subsurface characteristics. [14]

Seismic velocity structures are inferred through inverse modeling, fitting theoretical models to observed data. However, different models can often explain the same data, leading to non-unique solutions. [102] This issue is compounded when inverse problems are poorly conditioned, where small data variations can suggest drastically different subsurface structures. [103]

In contrast to Earth, the seismic datasets for the Moon and Mars are sparse. [13] The Apollo missions deployed a handful of seismometers across the Moon, and Mars's seismic data is limited to the InSight mission's findings. [56] [104] This scarcity restricts the resolution of velocity models for these celestial bodies and introduces greater uncertainty in interpreting their internal structures.

See also

Related Research Articles

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<span class="mw-page-title-main">Mohorovičić discontinuity</span> Boundary between the Earths crust and the mantle

The Mohorovičić discontinuity – usually called the Moho discontinuity, Moho boundary, or just Moho – is the boundary between the crust and the mantle of Earth. It is defined by the distinct change in velocity of seismic waves as they pass through changing densities of rock.

<span class="mw-page-title-main">Island arc</span> Arc-shaped archipelago formed by intense seismic activity of long chains of active volcanoes

Island arcs are long chains of active volcanoes with intense seismic activity found along convergent tectonic plate boundaries. Most island arcs originate on oceanic crust and have resulted from the descent of the lithosphere into the mantle along the subduction zone. They are the principal way by which continental growth is achieved.

<span class="mw-page-title-main">Rift valley</span> Linear lowland created by a tectonic rift or fault

A rift valley is a linear shaped lowland between several highlands or mountain ranges produced by the action of a geologic rift. Rifts are formed as a result of the pulling apart of the lithosphere due to extensional tectonics. The linear depression may subsequently be further deepened by the forces of erosion. More generally the valley is likely to be filled with sedimentary deposits derived from the rift flanks and the surrounding areas. In many cases rift lakes are formed. One of the best known examples of this process is the East African Rift. On Earth, rifts can occur at all elevations, from the sea floor to plateaus and mountain ranges in continental crust or in oceanic crust. They are often associated with a number of adjoining subsidiary or co-extensive valleys, which are typically considered part of the principal rift valley geologically.

<span class="mw-page-title-main">Planetary core</span> Innermost layer(s) of a planet

A planetary core consists of the innermost layers of a planet. Cores may be entirely solid or entirely liquid, or a mixture of solid and liquid layers as is the case in the Earth. In the Solar System, core sizes range from about 20% to 85% of a planet's radius (Mercury).

<span class="mw-page-title-main">Internal structure of Earth</span>

The internal structure of Earth is the layers of the Earth, excluding its atmosphere and hydrosphere. The structure consists of an outer silicate solid crust, a highly viscous asthenosphere and solid mantle, a liquid outer core whose flow generates the Earth's magnetic field, and a solid inner core.

<span class="mw-page-title-main">Core–mantle boundary</span> Discontinuity where the bottom of the planets mantle meets the outer layer of the core

The core–mantle boundary (CMB) of Earth lies between the planet's silicate mantle and its liquid iron–nickel outer core, at a depth of 2,891 km (1,796 mi) below Earth's surface. The boundary is observed via the discontinuity in seismic wave velocities at that depth due to the differences between the acoustic impedances of the solid mantle and the molten outer core. P-wave velocities are much slower in the outer core than in the deep mantle while S-waves do not exist at all in the liquid portion of the core. Recent evidence suggests a distinct boundary layer directly above the CMB possibly made of a novel phase of the basic perovskite mineralogy of the deep mantle named post-perovskite. Seismic tomography studies have shown significant irregularities within the boundary zone and appear to be dominated by the African and Pacific Large low-shear-velocity provinces (LLSVP).

<span class="mw-page-title-main">Earth's inner core</span> Innermost part of Earth, a solid ball of iron-nickel alloy

Earth's inner core is the innermost geologic layer of the planet Earth. It is primarily a solid ball with a radius of about 1,220 km (760 mi), which is about 20% of Earth’s radius or 70% of the Moon's radius.

<span class="mw-page-title-main">Shadow zone</span> Area not reached by seismic waves from an earthquake

A seismic shadow zone is an area of the Earth's surface where seismographs cannot detect direct P waves and/or S waves from an earthquake. This is due to liquid layers or structures within the Earth's surface. The most recognized shadow zone is due to the core-mantle boundary where P waves are refracted and S waves are stopped at the liquid outer core; however, any liquid boundary or body can create a shadow zone. For example, magma reservoirs with a high enough percent melt can create seismic shadow zones.

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.

<span class="mw-page-title-main">Marsquake</span> Seismic event occurring on Mars

A marsquake is a quake which, much like an earthquake, would be a shaking of the surface or interior of the planet Mars as a result of the sudden release of energy in the planet's interior, such as the result of plate tectonics, which most quakes on Earth originate from, or possibly from hotspots such as Olympus Mons or the Tharsis Montes. The detection and analysis of marsquakes could be informative to probing the interior structure of Mars, as well as identifying whether any of Mars's many volcanoes continue to be volcanically active.

<span class="mw-page-title-main">Internal structure of the Moon</span>

Having a mean density of 3,346.4 kg/m3, the Moon is a differentiated body, being composed of a geochemically distinct crust, mantle, and planetary core. This structure is believed to have resulted from the fractional crystallization of a magma ocean shortly after its formation about 4.5 billion years ago. The energy required to melt the outer portion of the Moon is commonly attributed to a giant impact event that is postulated to have formed the Earth-Moon system, and the subsequent reaccretion of material in Earth orbit. Crystallization of this magma ocean would have given rise to a mafic mantle and a plagioclase-rich crust.

The Hollow Moon and the closely related Spaceship Moon are pseudoscientific hypotheses that propose that Earth's Moon is either wholly hollow or otherwise contains a substantial interior space. No scientific evidence exists to support the idea; seismic observations and other data collected since spacecraft began to orbit or land on the Moon indicate that it has a thin crust, extensive mantle and small, dense core. Overall it is much less dense than Earth.

Pyrolite is a term used to characterize a model composition of the Earth's mantle. This model is based on that a pyrolite source can produce the Mid-Ocean Ridge Basalt by partial melting. It was first proposed by Ted Ringwood (1962) as being 1 part basalt and 4 parts harzburgite, but later was revised to being 1 part tholeiitic basalt and 3 parts dunite. The term is derived from the mineral names PYR-oxene and OL-ivine. However, whether pyrolite is representative of the Earth's mantle remains debated.

<span class="mw-page-title-main">Lunar seismology</span> Study of ground motions of the Moon

Lunar seismology is the study of ground motions of the Moon and the events, typically impacts or moonquakes, that excite them.

<span class="mw-page-title-main">Low-velocity zone</span>

The low-velocity zone (LVZ) occurs close to the boundary between the lithosphere and the asthenosphere in the upper mantle. It is characterized by unusually low seismic shear wave velocity compared to the surrounding depth intervals. This range of depths also corresponds to anomalously high electrical conductivity. It is present between about 80 and 300 km depth. This appears to be universally present for S waves, but may be absent in certain regions for P waves. A second low-velocity zone has been detected in a thin ≈50 km layer at the core-mantle boundary. These LVZs may have important implications for plate tectonics and the origin of the Earth's crust.

Roger Jay Phillips was an American geophysicist, planetary scientist, and professor emeritus at the Washington University in St. Louis. His research interests included the geophysical structure of planets, and the use of radar and gravity to investigate the surfaces and interiors of the planets.

<span class="mw-page-title-main">Lower mantle</span> The region from 660 to 2900 km below Earths surface

The lower mantle, historically also known as the mesosphere, represents approximately 56% of Earth's total volume, and is the region from 660 to 2900 km below Earth's surface; between the transition zone and the outer core. The preliminary reference Earth model (PREM) separates the lower mantle into three sections, the uppermost (660–770 km), mid-lower mantle (770–2700 km), and the D layer (2700–2900 km). Pressure and temperature in the lower mantle range from 24–127 GPa and 1900–2600 K. It has been proposed that the composition of the lower mantle is pyrolitic, containing three major phases of bridgmanite, ferropericlase, and calcium-silicate perovskite. The high pressure in the lower mantle has been shown to induce a spin transition of iron-bearing bridgmanite and ferropericlase, which may affect both mantle plume dynamics and lower mantle chemistry.

The upper mantle of Earth is a very thick layer of rock inside the planet, which begins just beneath the crust and ends at the top of the lower mantle at 670 km (420 mi). Temperatures range from approximately 500 K at the upper boundary with the crust to approximately 1,200 K at the boundary with the lower mantle. Upper mantle material that has come up onto the surface comprises about 55% olivine, 35% pyroxene, and 5 to 10% of calcium oxide and aluminum oxide minerals such as plagioclase, spinel, or garnet, depending upon depth.

References

  1. 1 2 3 4 5 6 7 8 Dziewonski, Adam M.; Woodhouse, John H. (1987-04-03). "Global Images of the Earth's Interior". Science. 236 (4797): 37–48. Bibcode:1987Sci...236...37D. doi:10.1126/science.236.4797.37. ISSN   0036-8075. PMID   17759204. S2CID   31488210.
  2. ↑ Mavko, Gary; Mukerji, Tapan; Dvorkin, Jack (2009). The Rock Physics Handbook: Tools for Seismic Analysis of Porous Media (2 ed.). Cambridge: Cambridge University Press. doi:10.1017/CBO9780511626753. ISBN   9780521861366.
  3. 1 2 3 4 5 6 7 8 Shearer, Peter M. (2019-05-30). Introduction to Seismology (3 ed.). Cambridge University Press. Bibcode:2019inse.book.....S. doi:10.1017/9781316877111. ISBN   978-1-316-87711-1. S2CID   263550804.
  4. ↑ "GSN Stations". earthquake.usgs.gov. Retrieved 2023-11-13.
  5. 1 2 Mohorovičić, A. (1910). "Das Beben vom 8. X. 1909". Gerlands Beiträge zur Geophysik. 15 (60105).
  6. ↑ Gutenberg, B (1959). Physics of the Earth's Interior. Academic Press.
  7. ↑ Oliver, Jack; Murphy, Leonard (1971-10-15). "WWNSS: Seismology's Global Network of Observing Stations: Standardized collection and efficient distribution of earthquake data yield social and scientific rewards". Science. 174 (4006): 254–261. doi:10.1126/science.174.4006.254. ISSN   0036-8075. PMID   17778051. S2CID   27711713.
  8. ↑ Isacks, Bryan; Oliver, Jack; Sykes, Lynn R. (1968-09-15). "Seismology and the new global tectonics". Journal of Geophysical Research. 73 (18): 5855–5899. Bibcode:1968JGR....73.5855I. doi:10.1029/jb073i018p05855. ISSN   0148-0227.
  9. ↑ Aki, Keiiti; Christoffersson, Anders; Husebye, Eystein S. (1977-01-10). "Determination of the three-dimensional seismic structure of the lithosphere". Journal of Geophysical Research. 82 (2): 277–296. Bibcode:1977JGR....82..277A. doi:10.1029/jb082i002p00277. ISSN   0148-0227.
  10. 1 2 Dziewonski, Adam M.; Hager, Bradford H.; O'Connell, Richard J. (1977-01-10). "Large-scale heterogeneities in the lower mantle". Journal of Geophysical Research. 82 (2): 239–255. Bibcode:1977JGR....82..239D. doi:10.1029/jb082i002p00239. ISSN   0148-0227.
  11. ↑ Sengupta, M. K.; Toksöz, M. N. (1976). "Three dimensional model of seismic velocity variation in the Earth's mantle". Geophysical Research Letters. 3 (2): 84–86. Bibcode:1976GeoRL...3...84S. doi: 10.1029/gl003i002p00084 . ISSN   0094-8276.
  12. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 Dziewonski, Adam M.; Anderson, Don L. (1981). "Preliminary reference Earth model". Physics of the Earth and Planetary Interiors. 25 (4): 297–356. Bibcode:1981PEPI...25..297D. doi:10.1016/0031-9201(81)90046-7. ISSN   0031-9201.
  13. 1 2 Butler, Rhett; Lay, Thome; Creager, Ken; Earl, Paul; Fischer, Karen; Gaherty, Jim; Laske, Gabi; Leith, Bill; Park, Jeff; Ritzwolle, Mike; Tromp, Jeroen; Wen, Lianxing (2004-06-08). "The global seismographic network surpasses its design goal". Eos, Transactions American Geophysical Union. 85 (23): 225–229. Bibcode:2004EOSTr..85..225B. doi: 10.1029/2004EO230001 . ISSN   0096-3941.
  14. 1 2 3 Romanowicz, Barbara (2003). "Global Mantle Tomography: Progress Status in the Past 10 Years". Annual Review of Earth and Planetary Sciences. 31 (1): 303–328. Bibcode:2003AREPS..31..303R. doi:10.1146/annurev.earth.31.091602.113555. ISSN   0084-6597.
  15. ↑ Rawlinson, N.; Sambridge, M. (2003), Seismic Traveltime Tomography of the Crust and Lithosphere, Advances in Geophysics, vol. 46, Elsevier, pp. 81–198, doi:10.1016/s0065-2687(03)46002-0, ISBN   978-0-12-018846-8 , retrieved 2023-10-01
  16. 1 2 3 4 5 6 Costa de Lima, Thuany; Phạm, Thanh-Son; Ma, Xiaolong; Tkalčić, Hrvoje (2023-07-29). "An estimate of absolute shear-wave speed in the Earth's inner core". Nature Communications. 14 (1): 4577. Bibcode:2023NatCo..14.4577C. doi:10.1038/s41467-023-40307-9. ISSN   2041-1723. PMC   10387060 . PMID   37516735. S2CID   260315423.
  17. ↑ Liu, Xin; Beroza, Gregory C.; Ben-Zion, Yehuda (2022-08-16). "Ambient Noise Attenuation Tomography Reveals an Asymmetric Damage Zone Across San Jacinto Fault Near Anza, California". Geophysical Research Letters. 49 (15). Bibcode:2022GeoRL..4999562L. doi: 10.1029/2022GL099562 . ISSN   0094-8276. S2CID   251078656.
  18. ↑ Redpath, B.B. (1973-05-01). Seismic refraction exploration for engineering site investigations (Report). Office of Scientific and Technical Information (OSTI). doi:10.2172/4409605.
  19. 1 2 Holbrook, W.S.; Mooney, W.D.; Christensen, N.I. "The seismic velocity structure of the deep continental crust". Continental Lower Crust. 23: 1–43.
  20. ↑ Eberhart-Phillips, Donna (1990-09-10). "Three-dimensional P and S velocity structure in the Coalinga Region, California". Journal of Geophysical Research: Solid Earth. 95 (B10): 15343–15363. Bibcode:1990JGR....9515343E. doi:10.1029/jb095ib10p15343. ISSN   0148-0227.
  21. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Goins, N. R.; Dainty, A. M.; Toksöz, M. N. (1981-06-10). "Lunar seismology: The internal structure of the Moon". Journal of Geophysical Research: Solid Earth. 86 (B6): 5061–5074. Bibcode:1981JGR....86.5061G. doi:10.1029/jb086ib06p05061. hdl: 1721.1/52843 . ISSN   0148-0227.
  22. 1 2 3 4 5 6 7 8 9 10 11 12 Khan, Amir; Ceylan, Savas; van Driel, Martin; Giardini, Domenico; Lognonné, Philippe; Samuel, Henri; Schmerr, Nicholas C.; Stähler, Simon C.; Duran, Andrea C.; Huang, Quancheng; Kim, Doyeon; Broquet, Adrien; Charalambous, Constantinos; Clinton, John F.; Davis, Paul M. (2021-07-23). "Upper mantle structure of Mars from InSight seismic data". Science. 373 (6553): 434–438. Bibcode:2021Sci...373..434K. doi:10.1126/science.abf2966. ISSN   0036-8075. PMID   34437116. S2CID   236179554.
  23. 1 2 3 Kim, D.; Banerdt, W. B.; Ceylan, S.; Giardini, D.; Lekić, V.; Lognonné, P.; Beghein, C.; Beucler, é.; Carrasco, S.; Charalambous, C.; Clinton, J.; Drilleau, M.; Durán, C.; Golombek, M.; Joshi, R. (2022-10-28). "Surface waves and crustal structure on Mars". Science. 378 (6618): 417–421. Bibcode:2022Sci...378..417K. doi:10.1126/science.abq7157. hdl: 10919/117381 . ISSN   0036-8075. PMID   36302020. S2CID   253184234.
  24. 1 2 3 4 5 6 7 Stähler, Simon C.; Khan, Amir; Banerdt, W. Bruce; Lognonné, Philippe; Giardini, Domenico; Ceylan, Savas; Drilleau, Mélanie; Duran, A. Cecilia; Garcia, Raphaël F.; Huang, Quancheng; Kim, Doyeon; Lekic, Vedran; Samuel, Henri; Schimmel, Martin; Schmerr, Nicholas (2021-07-23). "Seismic detection of the martian core". Science. 373 (6553): 443–448. Bibcode:2021Sci...373..443S. doi:10.1126/science.abi7730. hdl: 20.500.11850/498074 . ISSN   0036-8075. PMID   34437118. S2CID   236179579.
  25. 1 2 3 4 5 Samuel, Henri; Drilleau, Mélanie; Rivoldini, Attilio; Xu, Zongbo; Huang, Quancheng; Garcia, Raphaël F.; Lekić, Vedran; Irving, Jessica C. E.; Badro, James; Lognonné, Philippe H.; Connolly, James A. D.; Kawamura, Taichi; Gudkova, Tamara; Banerdt, William B. (2023). "Geophysical evidence for an enriched molten silicate layer above Mars's core". Nature. 622 (7984): 712–717. Bibcode:2023Natur.622..712S. doi:10.1038/s41586-023-06601-8. ISSN   1476-4687. PMC   10600000 . PMID   37880437.
  26. 1 2 3 4 Nakamura, Yosio; Latham, Gary; Lammlein, David; Ewing, Maurice; Duennebier, Frederick; Dorman, James (1974). "Deep lunar interior inferred from recent seismic data". Geophysical Research Letters. 1 (3): 137–140. Bibcode:1974GeoRL...1..137N. doi:10.1029/gl001i003p00137. ISSN   0094-8276.
  27. 1 2 3 4 5 6 7 8 9 10 Weber, Renee C.; Lin, Pei-Ying; Garnero, Edward J.; Williams, Quentin; Lognonné, Philippe (2011-01-21). "Seismic Detection of the Lunar Core". Science. 331 (6015): 309–312. Bibcode:2011Sci...331..309W. doi:10.1126/science.1199375. ISSN   0036-8075. PMID   21212323. S2CID   206530647.
  28. 1 2 Khan, A. (2004). "Does the Moon possess a molten core? Probing the deep lunar interior using results from LLR and Lunar Prospector". Journal of Geophysical Research. 109 (E9). Bibcode:2004JGRE..109.9007K. doi: 10.1029/2004je002294 . ISSN   0148-0227.
  29. 1 2 3 4 5 6 7 8 Zheng, Yingcai; Nimmo, Francis; Lay, Thorne (2015). "Seismological implications of a lithospheric low seismic velocity zone in Mars". Physics of the Earth and Planetary Interiors. 240: 132–141. Bibcode:2015PEPI..240..132Z. doi:10.1016/j.pepi.2014.10.004. ISSN   0031-9201.
  30. 1 2 Tian, Dongdong; Lv, Mingda; Wei, S. Shawn; Dorfman, Susannah M.; Shearer, Peter M. (2020-12-15). "Global variations of Earth's 520- and 560-km discontinuities". Earth and Planetary Science Letters. 552: 116600. Bibcode:2020E&PSL.55216600T. doi: 10.1016/j.epsl.2020.116600 . ISSN   0012-821X. S2CID   224984410.
  31. ↑ Christensen, Nikolas I.; Mooney, Walter D. (1995-06-10). "Seismic velocity structure and composition of the continental crust: A global view". Journal of Geophysical Research: Solid Earth. 100 (B6): 9761–9788. Bibcode:1995JGR...100.9761C. doi:10.1029/95jb00259. ISSN   0148-0227.
  32. ↑ Birch, Francis (1961). "The velocity of compressional waves in rocks to 10 kilobars: 2". Journal of Geophysical Research. 66 (7): 2199–2224. doi:10.1029/jz066i007p02199. ISSN   0148-0227.
  33. ↑ Rudnick, Roberta L.; Fountain, David M. (1995). "Nature and composition of the continental crust: A lower crustal perspective". Reviews of Geophysics. 33 (3): 267–309. Bibcode:1995RvGeo..33..267R. doi:10.1029/95rg01302. ISSN   8755-1209.
  34. 1 2 Lay, T; Wallace, T.C. (1995). Modern global seismology. Academic Press.
  35. 1 2 3 4 Irifune, T.; Ringwood, A.E. (1987). "Phase transformations in a harzburgite composition to 26 GPa: implications for dynamical behaviour of the subducting slab". Earth and Planetary Science Letters. 86 (2–4): 365–376. Bibcode:1987E&PSL..86..365I. doi:10.1016/0012-821x(87)90233-0. ISSN   0012-821X.
  36. ↑ Duffy, Thomas S.; Anderson, Don L. (1989-02-10). "Seismic velocities in mantle minerals and the mineralogy of the upper mantle". Journal of Geophysical Research: Solid Earth. 94 (B2): 1895–1912. Bibcode:1989JGR....94.1895D. doi: 10.1029/jb094ib02p01895 . ISSN   0148-0227.
  37. ↑ Lay, Thorne; Hernlund, John; Buffett, Bruce A. (2008). "Core–mantle boundary heat flow". Nature Geoscience. 1 (1): 25–32. Bibcode:2008NatGe...1...25L. doi:10.1038/ngeo.2007.44. ISSN   1752-0894.
  38. ↑ MacDonald, G.J.; Knopoff, L (1958). "On the chemical composition of the outer core". Geophysical Journal of the Royal Astronomical Society. 1 (4): 284–297. doi: 10.1111/j.1365-246X.1958.tb05338.x .
  39. ↑ BULLEN, K. E. (1973). "Cores of the Terrestrial Planets". Nature. 243 (5402): 68–70. Bibcode:1973Natur.243...68B. doi:10.1038/243068a0. ISSN   0028-0836. S2CID   4272176.
  40. ↑ Fukai, Yuh; Suzuki, Toshihiro (1986-08-10). "Iron-water reaction under high pressure and its implication in the evolution of the Earth". Journal of Geophysical Research: Solid Earth. 91 (B9): 9222–9230. Bibcode:1986JGR....91.9222F. doi:10.1029/jb091ib09p09222. ISSN   0148-0227.
  41. ↑ Masters, Guy; Gubbins, David (2003). "On the resolution of density within the Earth". Physics of the Earth and Planetary Interiors. 140 (1–3): 159–167. Bibcode:2003PEPI..140..159M. doi:10.1016/j.pepi.2003.07.008. ISSN   0031-9201.
  42. 1 2 3 4 5 Song, Xiaodong; Helmberger, Don V. (1998-10-30). "Seismic Evidence for an Inner Core Transition Zone". Science. 282 (5390): 924–927. Bibcode:1998Sci...282..924S. doi:10.1126/science.282.5390.924. ISSN   0036-8075. PMID   9794758.
  43. 1 2 3 4 Anderson, Don L. (2002-10-21). "The inner inner core of Earth". Proceedings of the National Academy of Sciences. 99 (22): 13966–13968. Bibcode:2002PNAS...9913966A. doi: 10.1073/pnas.232565899 . ISSN   0027-8424. PMC   137819 . PMID   12391308.
  44. ↑ Badding, J. V.; Mao, H. K.; Hemley, R. J. (2013-03-18), "High-Pressure Crystal Structure and Equation of State of Iron Hydride: Implications for the Earth's Core", High-Pressure Research: Application to Earth and Planetary Sciences, Geophysical Monograph Series, Washington, D. C.: American Geophysical Union, pp. 363–371, doi:10.1029/gm067p0363, ISBN   9781118663929 , retrieved 2023-10-05
  45. ↑ Poirier, Jean-Paul (1994). "Light elements in the Earth's outer core: A critical review". Physics of the Earth and Planetary Interiors. 85 (3–4): 319–337. Bibcode:1994PEPI...85..319P. doi:10.1016/0031-9201(94)90120-1. ISSN   0031-9201.
  46. 1 2 Irving, J. C. E.; Deuss, A. (2011-04-14). "Hemispherical structure in inner core velocity anisotropy". Journal of Geophysical Research. 116 (B4). Bibcode:2011JGRB..116.4307I. doi:10.1029/2010jb007942. ISSN   0148-0227.
  47. ↑ Kennett, B. L. N.; Engdahl, E. R.; Buland, R. (1995). "Constraints on seismic velocities in the Earth from traveltimes". Geophysical Journal International. 122 (1): 108–124. Bibcode:1995GeoJI.122..108K. doi: 10.1111/j.1365-246x.1995.tb03540.x . ISSN   0956-540X. S2CID   130016683.
  48. ↑ Ritsema, Jeroen; Lekić, Vedran (2020-05-30). "Heterogeneity of Seismic Wave Velocity in Earth's Mantle". Annual Review of Earth and Planetary Sciences. 48 (1): 377–401. Bibcode:2020AREPS..48..377R. doi:10.1146/annurev-earth-082119-065909. ISSN   0084-6597. S2CID   212965198.
  49. ↑ Nunn, Ceri; Garcia, Raphael F.; Nakamura, Yosio; Marusiak, Angela G.; Kawamura, Taichi; Sun, Daoyuan; Margerin, Ludovic; Weber, Renee; Drilleau, Mélanie; Wieczorek, Mark A.; Khan, Amir; Rivoldini, Attilio; Lognonné, Philippe; Zhu, Peimin (2020-07-03). "Lunar Seismology: A Data and Instrumentation Review". Space Science Reviews. 216 (5): 89. Bibcode:2020SSRv..216...89N. doi: 10.1007/s11214-020-00709-3 . hdl: 20.500.11850/425940 . ISSN   1572-9672. S2CID   255061068.
  50. 1 2 3 "Moonquakes and marsquakes: How we peer inside other worlds | Research and Innovation". ec.europa.eu. 10 August 2020. Retrieved 2023-10-08.
  51. 1 2 Nakamura, Yosio; Latham, Gary V.; Dorman, H. James (1982-11-15). "Apollo Lunar Seismic Experiment—Final summary". Journal of Geophysical Research: Solid Earth. 87 (S01): 117. Bibcode:1982LPSC...13..117N. doi:10.1029/jb087is01p0a117. ISSN   0148-0227.
  52. ↑ Zhao, DaPeng; Lei, JianShe; Liu, Lucy (2008-11-03). "Seismic tomography of the Moon". Science Bulletin. 53 (24): 3897–3907. Bibcode:2008SciBu..53.3897Z. doi:10.1007/s11434-008-0484-1. ISSN   2095-9273. S2CID   140565761.
  53. 1 2 Jolliff, Bradley L.; Gillis, Jeffrey J.; Haskin, Larry A.; Korotev, Randy L.; Wieczorek, Mark A. (2000). "Major lunar crustal terranes: Surface expressions and crust-mantle origins". Journal of Geophysical Research: Planets. 105 (E2): 4197–4216. Bibcode:2000JGR...105.4197J. doi: 10.1029/1999je001103 . ISSN   0148-0227. S2CID   85510409.
  54. 1 2 3 Borgomano; Fortin; Guéguen (2019-11-09). "Cracked, Porous Rocks and Fluids: Moon and Earth Paradox". Minerals. 9 (11): 693. Bibcode:2019Mine....9..693B. doi: 10.3390/min9110693 . ISSN   2075-163X.
  55. 1 2 3 4 5 6 Kovach, Robert L.; Watkins, Joel S. (1973). "The velocity structure of the lunar crust". The Moon. 7 (1–2): 63–75. Bibcode:1973Moon....7...63K. doi:10.1007/bf00578808. ISSN   0027-0903. S2CID   122220556.
  56. 1 2 3 Nakamura, Yosio (2005). "Farside deep moonquakes and deep interior of the Moon". Journal of Geophysical Research. 110 (E1). Bibcode:2005JGRE..110.1001N. doi: 10.1029/2004je002332 . ISSN   0148-0227.
  57. 1 2 3 4 5 Nakamura, Yosio (1983-01-10). "Seismic velocity structure of the lunar mantle". Journal of Geophysical Research: Solid Earth. 88 (B1): 677–686. Bibcode:1983JGR....88..677N. doi:10.1029/jb088ib01p00677. ISSN   0148-0227.
  58. ↑ Lognonné, Philippe; Gagnepain-Beyneix, Jeannine; Chenet, Hugues (2003). "A new seismic model of the Moon: implications for structure, thermal evolution and formation of the Moon". Earth and Planetary Science Letters. 211 (1–2): 27–44. Bibcode:2003E&PSL.211...27L. doi:10.1016/s0012-821x(03)00172-9. ISSN   0012-821X.
  59. 1 2 Wieczorek, M. A. (2006-01-01). "The Constitution and Structure of the Lunar Interior". Reviews in Mineralogy and Geochemistry. 60 (1): 221–364. Bibcode:2006RvMG...60..221W. doi:10.2138/rmg.2006.60.3. ISSN   1529-6466.
  60. ↑ Brett, R (1972). "Sulfur and the ancient lunar magnetic field". Trans Am. Geophys. Union. 53: 723.
  61. 1 2 Wieczorek, Mark A.; Neumann, Gregory A.; Nimmo, Francis; Kiefer, Walter S.; Taylor, G. Jeffrey; Melosh, H. Jay; Phillips, Roger J.; Solomon, Sean C.; Andrews-Hanna, Jeffrey C.; Asmar, Sami W.; Konopliv, Alexander S.; Lemoine, Frank G.; Smith, David E.; Watkins, Michael M.; Williams, James G. (2013-02-08). "The Crust of the Moon as Seen by GRAIL". Science. 339 (6120): 671–675. Bibcode:2013Sci...339..671W. doi:10.1126/science.1231530. ISSN   0036-8075. PMC   6693503 . PMID   23223394.
  62. 1 2 Banerdt, W. Bruce; Smrekar, Suzanne E.; Banfield, Don; Giardini, Domenico; Golombek, Matthew; Johnson, Catherine L.; Lognonné, Philippe; Spiga, Aymeric; Spohn, Tilman; Perrin, Clément; Stähler, Simon C.; Antonangeli, Daniele; Asmar, Sami; Beghein, Caroline; Bowles, Neil (2020). "Initial results from the InSight mission on Mars". Nature Geoscience. 13 (3): 183–189. Bibcode:2020NatGe..13..183B. doi:10.1038/s41561-020-0544-y. ISSN   1752-0894. S2CID   211266334.
  63. ↑ Anderson, Don L.; Miller, W. F.; Latham, G. V.; Nakamura, Y.; Toksöz, M. N.; Dainty, A. M.; Duennebier, F. K.; Lazarewicz, A. R.; Kovach, R. L.; Knight, T. C. D. (1977-09-30). "Seismology on Mars". Journal of Geophysical Research. 82 (28): 4524–4546. Bibcode:1977JGR....82.4524A. doi:10.1029/js082i028p04524. ISSN   0148-0227.
  64. 1 2 "Mars: Facts - NASA Science". science.nasa.gov. Retrieved 2023-10-08.
  65. 1 2 3 Lognonné, P.; Banerdt, W. B.; Pike, W. T.; Giardini, D.; Christensen, U.; Garcia, R. F.; Kawamura, T.; Kedar, S.; Knapmeyer-Endrun, B.; Margerin, L.; Nimmo, F.; Panning, M.; Tauzin, B.; Scholz, J.-R.; Antonangeli, D. (2020). "Constraints on the shallow elastic and anelastic structure of Mars from InSight seismic data". Nature Geoscience. 13 (3): 213–220. Bibcode:2020NatGe..13..213L. doi:10.1038/s41561-020-0536-y. hdl: 10261/204850 . ISSN   1752-0908. S2CID   211265507.
  66. ↑ Hemingway, Douglas J.; Driscoll, Peter E. (2021). "History and Future of the Martian Dynamo and Implications of a Hypothetical Solid Inner Core". Journal of Geophysical Research: Planets. 126 (4). Bibcode:2021JGRE..12606663H. doi:10.1029/2020JE006663. ISSN   2169-9097. S2CID   233738133.
  67. ↑ Giardini, Domenico; Lognonne, Philippe; Banerdt, Bruce; Boese, Maren; Ceylan, Savas; Clinton, John; van Driel, Martin; Garcia, Raphael; Kawamura, Taichi (2020-03-23). "Seismicity of Mars". Egu General Assembly Conference Abstracts: 20437. Bibcode:2020EGUGA..2220437G. doi: 10.5194/egusphere-egu2020-20437 .
  68. 1 2 3 4 Dapré, K.; Irving, J.C.E. (2024). "Global seismology in the interior of Enceladus". Icarus. 408: 115806. Bibcode:2024Icar..40815806D. doi: 10.1016/j.icarus.2023.115806 . ISSN   0019-1035. S2CID   262210868.
  69. ↑ Hoolst, Tim Van; Baland, Rose-Marie; Trinh, Antony (2016). "The diurnal libration and interior structure of Enceladus". Icarus. 277: 311–318. Bibcode:2016Icar..277..311V. doi:10.1016/j.icarus.2016.05.025. ISSN   0019-1035.
  70. ↑ McKinnon, William B. (2015-04-10). "Effect of Enceladus's rapid synchronous spin on interpretation of Cassini gravity". Geophysical Research Letters. 42 (7): 2137–2143. Bibcode:2015GeoRL..42.2137M. doi: 10.1002/2015gl063384 . ISSN   0094-8276. S2CID   135340263.
  71. 1 2 Čadek, Ondřej; Tobie, Gabriel; Van Hoolst, Tim; Massé, Marion; Choblet, Gaël; Lefèvre, Axel; Mitri, Giuseppe; Baland, Rose-Marie; Běhounková, Marie; Bourgeois, Olivier; Trinh, Anthony (2016-06-11). "Enceladus's internal ocean and ice shell constrained from Cassini gravity, shape, and libration data". Geophysical Research Letters. 43 (11): 5653–5660. Bibcode:2016GeoRL..43.5653C. doi: 10.1002/2016gl068634 . ISSN   0094-8276. S2CID   133015695.
  72. 1 2 Neumann, Wladimir; Kruse, Antonio (2019-08-30). "Differentiation of Enceladus and Retention of a Porous Core". The Astrophysical Journal. 882 (1): 47. Bibcode:2019ApJ...882...47N. doi: 10.3847/1538-4357/ab2fcf . ISSN   1538-4357.
  73. 1 2 Vance, Steven D.; Panning, Mark P.; Stähler, Simon; Cammarano, Fabio; Bills, Bruce G.; Tobie, Gabriel; Kamata, Shunichi; Kedar, Sharon; Sotin, Christophe; Pike, William T.; Lorenz, Ralph; Huang, Hsin-Hua; Jackson, Jennifer M.; Banerdt, Bruce (2018). "Geophysical Investigations of Habitability in Ice-Covered Ocean Worlds". Journal of Geophysical Research: Planets. 123 (1): 180–205. arXiv: 1705.03999 . Bibcode:2018JGRE..123..180V. doi:10.1002/2017je005341. ISSN   2169-9097. S2CID   253094329.
  74. ↑ Olsen, Kira G.; Hurford, Terry A.; Schmerr, Nicholas C.; Huang, Mong-Han; Brunt, Kelly M.; Zipparo, Sophia; Cole, Hank M.; Aster, Richard C. (2021). "Projected Seismic Activity at the Tiger Stripe Fractures on Enceladus, Saturn, From an Analog Study of Tidally Modulated Icequakes Within the Ross Ice Shelf, Antarctica". Journal of Geophysical Research: Planets. 126 (6). Bibcode:2021JGRE..12606862O. doi:10.1029/2021je006862. ISSN   2169-9097. S2CID   236377650.
  75. ↑ VOOSEN, P (2019). "Without a champion, Europa lander falls to NASA's back burner" . Retrieved 2023-10-09.
  76. ↑ "Home | Seismometer to Investigate Ice and Ocean Structure (SIIOS)". www.lpl.arizona.edu. Retrieved 2023-10-08.
  77. ↑ Marusiak, Angela; DellaGiustina, Daniella; Bailey, S. Hop; Bray, Veronica; Avenson, Brad; Pettit, Erin; Weber, Renee; Schmerr, Nicholas; Wagner, Natalie (2019-12-11). "Ambient Seismicity on Europan Analogs using the Seismometer to Investigate Ice and Ocean Structure (SIIOS)". Ess Open Archive ePrints. 105. Bibcode:2019esoar.10501283M. doi:10.1002/essoar.10501282.1 . Retrieved 2023-10-08.
  78. ↑ "NASA: Artemis" . Retrieved 2023-10-09.
  79. ↑ "DALI". NASA Glenn Research Centre. Retrieved 2023-10-09.
  80. ↑ Palmer, Derecke (1980), "1. Introduction", The Generalized Reciprocal Method of Seismic Refraction Interpretation, Society of Exploration Geophysicists, pp. 1–2, doi:10.1190/1.9781560802426.ch1, ISBN   978-0-931830-14-3 , retrieved 2023-10-04
  81. ↑ Sheriff, R. E.; Geldart, L. P. (1995-08-25). Exploration Seismology. Cambridge University Press. doi:10.1017/cbo9781139168359. ISBN   978-0-521-46282-2.
  82. 1 2 3 Telford, W. M.; Geldart, L. P.; Sheriff, R. E. (1990-10-26). Applied Geophysics. Cambridge University Press. doi:10.1017/cbo9781139167932. ISBN   978-0-521-32693-3.
  83. ↑ Dziewonski, A. M.; Chou, T.-A.; Woodhouse, J. H. (1981-04-10). "Determination of earthquake source parameters from waveform data for studies of global and regional seismicity". Journal of Geophysical Research: Solid Earth. 86 (B4): 2825–2852. Bibcode:1981JGR....86.2825D. doi:10.1029/jb086ib04p02825. ISSN   0148-0227.
  84. ↑ Nolet, Guust (2008-09-25). A Breviary of Seismic Tomography. Cambridge University Press. doi:10.1017/cbo9780511984709. ISBN   978-0-521-88244-6.
  85. ↑ Langston, Charles A. (1979-08-10). "Structure under Mount Rainier, Washington, inferred from teleseismic body waves". Journal of Geophysical Research: Solid Earth. 84 (B9): 4749–4762. Bibcode:1979JGR....84.4749L. doi:10.1029/jb084ib09p04749. ISSN   0148-0227.
  86. 1 2 Ligorría, Juan Pablo; Ammon, Charles J. (1999-10-01). "Iterative deconvolution and receiver-function estimation". Bulletin of the Seismological Society of America. 89 (5): 1395–1400. Bibcode:1999BuSSA..89.1395L. doi:10.1785/bssa0890051395. ISSN   1943-3573.
  87. ↑ Julià, J.; Ammon, C. J.; Herrmann, R. B.; Correig, A. M. (2000). "Joint inversion of receiver function and surface wave dispersion observations". Geophysical Journal International. 143 (1): 99–112. Bibcode:2000GeoJI.143...99J. doi: 10.1046/j.1365-246x.2000.00217.x . ISSN   0956-540X.
  88. ↑ Shapiro, N. M.; Campillo, M. (2004-04-08). "Emergence of broadband Rayleigh waves from correlations of the ambient seismic noise". Geophysical Research Letters. 31 (7): n/a. Bibcode:2004GeoRL..31.7614S. doi: 10.1029/2004gl019491 . ISSN   0094-8276. S2CID   26137057.
  89. 1 2 Lobkis, Oleg I.; Weaver, Richard L. (2001-12-01). "On the emergence of the Green's function in the correlations of a diffuse field". The Journal of the Acoustical Society of America. 110 (6): 3011–3017. Bibcode:2001ASAJ..110.3011L. doi:10.1121/1.1417528. ISSN   0001-4966.
  90. ↑ Bensen, G. D.; Ritzwoller, M. H.; Barmin, M. P.; Levshin, A. L.; Lin, F.; Moschetti, M. P.; Shapiro, N. M.; Yang, Y. (2007). "Processing seismic ambient noise data to obtain reliable broad-band surface wave dispersion measurements". Geophysical Journal International. 169 (3): 1239–1260. arXiv: 2007.03374 . Bibcode:2007GeoJI.169.1239B. doi:10.1111/j.1365-246x.2007.03374.x. ISSN   0956-540X. S2CID   229068738.
  91. ↑ Tarantola, Albert (1984). "Inversion of seismic reflection data in the acoustic approximation". Geophysics. 49 (8): 1259–1266. Bibcode:1984Geop...49.1259T. doi:10.1190/1.1441754. ISSN   0016-8033.
  92. ↑ Arnulf, A. F.; Harding, A. J.; Singh, S. C.; Kent, G. M.; Crawford, W. (2012). "Fine-scale velocity structure of upper oceanic crust from full waveform inversion of downward continued seismic reflection data at the Lucky Strike Volcano, Mid-Atlantic Ridge". Geophysical Research Letters. 39 (8): n/a. Bibcode:2012GeoRL..39.8303A. doi: 10.1029/2012gl051064 . ISSN   0094-8276. S2CID   129159004.
  93. ↑ Virieux, J.; Operto, S. (2009). "An overview of full-waveform inversion in exploration geophysics". Geophysics. 74 (6): WCC1–WCC26. doi:10.1190/1.3238367. ISSN   0016-8033. S2CID   43945073.
  94. ↑ Fichtner, Andreas; Kennett, Brian L. N.; Igel, Heiner; Bunge, Hans-Peter (2009). "Full seismic waveform tomography for upper-mantle structure in the Australasian region using adjoint methods". Geophysical Journal International. 179 (3): 1703–1725. Bibcode:2009GeoJI.179.1703F. doi:10.1111/j.1365-246x.2009.04368.x. ISSN   0956-540X. S2CID   20101319.
  95. 1 2 Fukao, Yoshio; Obayashi, Masayuki (2013). "Subducted slabs stagnant above, penetrating through, and trapped below the 660 km discontinuity". Journal of Geophysical Research: Solid Earth. 118 (11): 5920–5938. Bibcode:2013JGRB..118.5920F. doi: 10.1002/2013jb010466 . ISSN   2169-9313. S2CID   129872709.
  96. ↑ Koketsu, K; Miyake, H; Suzuki, H (2012). "Japan integrated velocity structure model version 1". In Proceedings of the 15th World Conference on Earthquake Engineering (Vol. 1, P. 4). Lisbon.
  97. 1 2 Sudo, Y.; Kong, L. (2001-06-22). "Three-dimensional seismic velocity structure beneath Aso Volcano, Kyushu, Japan". Bulletin of Volcanology. 63 (5): 326–344. Bibcode:2001BVol...63..326S. doi:10.1007/s004450100145. ISSN   0258-8900. S2CID   129741504.
  98. ↑ Engineering Geological Practice in Hong Kong. Geotechnical Engineering Office. 2007.
  99. ↑ Zelt, Colin A.; Azaria, Aron; Levander, Alan (2006). "3D seismic refraction traveltime tomography at a groundwater contamination site". Geophysics. 71 (5): H67–H78. Bibcode:2006Geop...71H..67Z. doi:10.1190/1.2258094. ISSN   0016-8033.
  100. ↑ Montagner, Jean-Paul; Tanimoto, Toshiro (1991-11-10). "Global upper mantle tomography of seismic velocities and anisotropies". Journal of Geophysical Research: Solid Earth. 96 (B12): 20337–20351. Bibcode:1991JGR....9620337M. doi:10.1029/91jb01890. ISSN   0148-0227.
  101. ↑ Zhao, Dapeng; Lei, Jianshe (2004). "Seismic ray path variations in a 3D global velocity model". Physics of the Earth and Planetary Interiors. 141 (3): 153–166. Bibcode:2004PEPI..141..153Z. doi:10.1016/j.pepi.2003.11.010. ISSN   0031-9201. S2CID   128762583.
  102. ↑ Tarantola, A.; Valette, B. (1981-10-22). "Inverse problems = Quest for information". Journal of Geophysics. 50 (1): 159–170. ISSN   2643-9271.
  103. ↑ Tarantola, Albert (2005). Inverse Problem Theory and Methods for Model Parameter Estimation. Society for Industrial and Applied Mathematics. doi:10.1137/1.9780898717921. ISBN   978-0-89871-572-9.
  104. ↑ Lognonné, P.; Banerdt, W. B.; Giardini, D.; Pike, W. T.; Christensen, U.; Laudet, P.; de Raucourt, S.; Zweifel, P.; Calcutt, S.; Bierwirth, M.; Hurst, K. J.; Ijpelaan, F.; Umland, J. W.; Llorca-Cejudo, R.; Larson, S. A. (2019-01-28). "SEIS: Insight's Seismic Experiment for Internal Structure of Mars". Space Science Reviews. 215 (1): 12. Bibcode:2019SSRv..215...12L. doi:10.1007/s11214-018-0574-6. ISSN   1572-9672. PMC   6394762 . PMID   30880848.
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