Effects of porosity on seismic velocities, elastic moduli and Poisson's ratios of solid materials and rocks

Yu, Chang-shui; Ji, Shaocheng; Li, Qi

doi:10.1016/j.jrmge.2015.07.004

Cited by 92 publications

(41 citation statements)

References 48 publications

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“…Seismic velocities are generally expected to decrease with increasing pore pressure. The precise influence of porosity on seismic velocities is complicated by the shape, distribution, and connectivity of pores and the presence of cracks and fractures, and few experiments exist that infer this relation (e.g., Christensen, ; Darot & Reuschlé, ; Todd & Simmons, ; Yu et al, ). We parameterize the decrease in V P as a function of porosity using the relation suggested by Wyllie et al ():

\frac{1}{V_{Pϕ}} = \frac{ϕ}{V_{fluid}} + \frac{1 - ϕ}{V_{P}} .

…”

Section: Methodsmentioning

confidence: 99%

Geophysical Investigations of Habitability in Ice‐Covered Ocean Worlds

et al. 2018

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Geophysical measurements can reveal the structures and thermal states of icy ocean worlds. The interior density, temperature, sound speed, and electrical conductivity thus characterize their habitability. We explore the variability and correlation of these parameters using 1‐D internal structure models. We invoke thermodynamic consistency using available thermodynamics of aqueous MgSO4, NaCl (as seawater), and NH3; pure water ice phases I, II, III, V, and VI; silicates; and any metallic core that may be present. Model results suggest, for Europa, that combinations of geophysical parameters might be used to distinguish an oxidized ocean dominated by MgSO4 from a more reduced ocean dominated by NaCl. In contrast with Jupiter's icy ocean moons, Titan and Enceladus have low‐density rocky interiors, with minimal or no metallic core. The low‐density rocky core of Enceladus may comprise hydrated minerals or anhydrous minerals with high porosity. Cassini gravity data for Titan indicate a high tidal potential Love number (k2>0.6), which requires a dense internal ocean (ρocean>1,200 kg m−3) and icy lithosphere thinner than 100 km. In that case, Titan may have little or no high‐pressure ice, or a surprisingly deep water‐rock interface more than 500 km below the surface, covered only by ice VI. Ganymede's water‐rock interface is the deepest among known ocean worlds, at around 800 km. Its ocean may contain multiple phases of high‐pressure ice, which will become buoyant if the ocean is sufficiently salty. Callisto's interior structure may be intermediate to those of Titan and Europa, with a water‐rock interface 250 km below the surface covered by ice V but not ice VI.

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\frac{1}{V_{Pϕ}} = \frac{ϕ}{V_{fluid}} + \frac{1 - ϕ}{V_{P}} .

…”

Section: Methodsmentioning

confidence: 99%

Geophysical Investigations of Habitability in Ice‐Covered Ocean Worlds

et al. 2018

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“…Among the 301 silicates, zircon displays the highest υ value (0.365) and quartz has the lowest υ value (0.080), while the other 299 minerals have their υ values between 0.200 and 0.350 with an average value of 0.261 (standard deviation of 0.030). These properties imply that rocks consisting of common rock‐forming silicate minerals should not be auxetic if they do not have porosity (Dunn & Ledbetter, ; Ji et al, ; Yu et al, ).…”

Section: Poisson's Ratios Of Natural Elements Oxides and Silicates mentioning

confidence: 99%

“…These values are close to that of quartz polycrystalline aggregate ( υ = 0.08 (McSkimin et al, )), suggesting that quartz is the most abundant mineral in these rocks. The progressive increase in Poisson's ratio with increasing pressure is thought to be caused by the gradual closure of microcracks and pores within the samples (Dunn & Ledbetter, ; Yu et al, ).…”

Section: Sedimentary Rocksmentioning

confidence: 99%

Poisson's Ratio and Auxetic Properties of Natural Rocks

Motra

et al. 2018

JGR Solid Earth

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Here we provide an appraisal of the Poisson's ratios (υ) for natural elements, common oxides, silicate minerals, and rocks with the purpose of searching for naturally auxetic materials. The Poisson's ratios of equivalently isotropic polycrystalline aggregates were calculated from dynamically measured elastic properties. Alpha‐cristobalite is currently the only known naturally occurring mineral that has exclusively negative υ values at 20–1,500°C. Quartz and potentially berlinite (AlPO4) display auxetic behavior in the vicinity of their α‐β structure transition. None of the crystalline igneous and metamorphic rocks (e.g., amphibolite, gabbro, granite, peridotite, and schist) display auxetic behavior at pressures of >5 MPa and room temperature. Our experimental measurements showed that quartz‐rich sedimentary rocks (i.e., sandstone and siltstone) are most likely to be the only rocks with negative Poisson's ratios at low confining pressures (≤200 MPa) because their main constituent mineral, α‐quartz, already has extremely low Poisson's ratio (υ = 0.08) and they contain microcracks, micropores, and secondary minerals. This finding may provide a new explanation for formation of dome‐and‐basin structures in quartz‐rich sedimentary rocks in response to a horizontal compressional stress in the upper crust.

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“…Temperature rise up to solidus or partial melting is even more unlikely. Mineral hydration is also unlikely beneath BSG because it leads to an R value greater than 1 (O'Connell & Budiansky, ; Takei, ; Yu et al, ) in contrast to the observed case where R ≈ 1. We interpret the observed velocity reductions as due to opening of pores (or cracks) within the upper crust in BSG.…”

Section: Interpretationsmentioning

confidence: 98%

Crustal Extension and Graben Formation by Fault Slip‐Associated Pore Opening, Kyushu, Japan

et al. 2019

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Crustal extension in graben takes place by normal (+strike-slip) faulting, yet the physical processes involved are poorly understood. A series of shallow large earthquakes struck the Kumamoto area of Kyushu, Japan, in 2016. The M w 7.0 main shock was a slip along the southern boundary of the Beppu-Shimabara Graben, where NS-extensional crustal deformation is now taking place. We conducted a tomographic inversion for crustal P and S velocities and Poisson's ratio (V p , V s , and σ) in Kyushu. The most outstanding feature in this region is a Beppu-Shimabara Graben-parallel belt of low V p and V s anomalies at depths of the upper crust. We find that within the belt dV s /V s ≈ dV p /V p (<0) in marked contrast to relations in other low-velocity regions where |dV s /V s | > |dV p /V p |. This observation can be interpreted as due to water-saturated, oblate-spheroid pores with either of two very different geometries: one almost round pore and the other very flat pore. We calculate 3-D density anomaly distributions and 2-D gravity anomaly profiles for these two pore models. The gravity anomaly map calculated for spherical pores shows a significant negative anomaly belt that spatially agrees with observed Bouguer anomaly map. The spatial agreement is very poor if pores are modeled as flat. This and extensive seismicity within Beppu-Shimabara Graben imply significance of fault-associated round pore formation in the process of graben opening. Seismic tomography combined with gravity and poroeasticty analyses can constrain the crack/pore state of extensionally deforming crust. Key Points:• Seismic tomography was conducted for 3-D distributions of P and S velocities and Poisson's ratio (V p , V s , and σ) in the crust, Kyushu, Japan • The graben actively opening and producing earthquakes is characterized by low V p and V s but little σ anomaly in the upper crust • Water-saturated round pore formation and shear deformation associated with seismic slip equally contribute to graben formation Supporting Information:• Supporting Information S1

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Effects of porosity on seismic velocities, elastic moduli and Poisson's ratios of solid materials and rocks

Cited by 92 publications

References 48 publications

Geophysical Investigations of Habitability in Ice‐Covered Ocean Worlds

Geophysical Investigations of Habitability in Ice‐Covered Ocean Worlds

Poisson's Ratio and Auxetic Properties of Natural Rocks

Crustal Extension and Graben Formation by Fault Slip‐Associated Pore Opening, Kyushu, Japan

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