Physics of the Earth and Planetary Interiors最新文献

{"title":"Elastic wave velocity measurements of sodium aluminosilicate glass and melt at high pressure and temperature","authors":"Naoki Takahashi ,&nbsp;Tatsuya Sakamaki ,&nbsp;Osamu Ikeda ,&nbsp;Sho Kakizawa ,&nbsp;Yuji Higo ,&nbsp;Akio Suzuki","doi":"10.1016/j.pepi.2024.107167","DOIUrl":"10.1016/j.pepi.2024.107167","url":null,"abstract":"<div><p>The combination of ultrasonic technique with synchrotron X-ray diffraction and radiography in a multi-anvil apparatus was utilized to measure the elastic wave velocities of sodium aluminosilicate glass and melt with the partially depolymerized composition of Na₃AlSi₃O₉ (NAS). The measurements were conducted at pressure and temperature of up to 7.3 GPa and at ambient temperature for glass and up to 4.3 GPa and 2120 K for melt, respectively. The compressional wave velocity (<em>V</em>_P) of the NAS glass remained mostly constant up to 4 GPa; subsequently, it increased with increasing pressure. Additionally, the NAS glass exhibited a minimum shear wave velocity (<em>V</em>_S) at 4–5 GPa. Alternatively, the <em>V</em>_P of the NAS melt was smaller than that of the NAS glass, showing a velocity minimum at ∼2 GPa. The negative pressure dependence of <em>V</em>_P of the NAS melt is completely different from the depolymerized diopside (Di) melt, which shows a monotonic increase in <em>V</em>_P with pressure. The contrasting behavior of the NAS and Di melts is caused by the difference in their structure, characterized by their degree of polymerization. Natural magma found in the interior of the Earth, such as basalt, has a partially depolymerized composition. This study indicates that the magma can exhibit elastic properties with negative pressure dependence, similar to the NAS melt.</p></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"350 ","pages":"Article 107167"},"PeriodicalIF":2.3,"publicationDate":"2024-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0031920124000256/pdfft?md5=5415ffd84d8ab5d465d2350f314ffe4c&pid=1-s2.0-S0031920124000256-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140129673","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spherical geometry convection in a fluid with an Arrhenius thermal viscosity dependence: The impact of core size and surface temperature on the scaling of stagnant-lid thickness and internal temperature","authors":"Pejvak Javaheri ,&nbsp;Julian P. Lowman ,&nbsp;Paul J. Tackley","doi":"10.1016/j.pepi.2024.107157","DOIUrl":"10.1016/j.pepi.2024.107157","url":null,"abstract":"&lt;div&gt;&lt;p&gt;The rock and rock-ice mixtures of the core-enveloping spherical shells comprising terrestrial body interiors have thermally determined viscosities well described by an Arrhenius dependence. Accordingly, the implied viscosity contrasts determined from the activation energies (E) characterizing such bodies can reach values exceeding &lt;span&gt;&lt;math&gt;&lt;msup&gt;&lt;mn&gt;10&lt;/mn&gt;&lt;mn&gt;40&lt;/mn&gt;&lt;/msup&gt;&lt;/math&gt;&lt;/span&gt;, for a temperature range that spans the conditions found from the lower mantle to the surface. In this study, we first explore the impact of implementing a cut-off to limit viscosity magnitude in cold regions. Using a spherical annulus geometry, we investigate the influence of core radius, surface temperature, and convective vigour on stagnant lid formation resulting from the extreme thermally induced viscosity contrasts. We demonstrate that the cut-off viscosity must be increased with decreasing curvature factor, &lt;span&gt;&lt;math&gt;&lt;mi&gt;f&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; (&lt;span&gt;&lt;math&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;msub&gt;&lt;mi&gt;r&lt;/mi&gt;&lt;mtext&gt;in&lt;/mtext&gt;&lt;/msub&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;msub&gt;&lt;mi&gt;r&lt;/mi&gt;&lt;mtext&gt;out&lt;/mtext&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;, where &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mi&gt;r&lt;/mi&gt;&lt;mtext&gt;in&lt;/mtext&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; and &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mi&gt;r&lt;/mi&gt;&lt;mtext&gt;out&lt;/mtext&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; are the inner and outer radii of the annulus, respectively), if the solutions are to be not only computationally manageable but physically valid. We find that for statistically-steady systems, the mean temperature decreases with core size, and that a viscosity contrast of at least &lt;span&gt;&lt;math&gt;&lt;msup&gt;&lt;mn&gt;10&lt;/mn&gt;&lt;mn&gt;7&lt;/mn&gt;&lt;/msup&gt;&lt;/math&gt;&lt;/span&gt; is required for stagnant lid formation as &lt;span&gt;&lt;math&gt;&lt;mi&gt;f&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; decreases below 0.5. Inverting the results from over 80 calculations featuring stagnant lids (from a total of approximately 180 calculations), we apply an energy balance model for heat flow across the thermal boundary layers and find that the non-dimensionalized temperature in the Approximately Isothermal Layer (AIL) in the convecting region under a stagnant lid is well predicted by &lt;span&gt;&lt;math&gt;&lt;msubsup&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;mi&gt;AIL&lt;/mi&gt;&lt;mo&gt;′&lt;/mo&gt;&lt;/msubsup&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mfrac&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mfrac&gt;&lt;mfenced&gt;&lt;mrow&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mfenced&gt;&lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;msubsup&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;mtext&gt;out&lt;/mtext&gt;&lt;mo&gt;′&lt;/mo&gt;&lt;/msubsup&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;mi&gt;γ&lt;/mi&gt;&lt;/mrow&gt;&lt;/mfenced&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;msqrt&gt;&lt;mrow&gt;&lt;msup&gt;&lt;mi&gt;γ&lt;/mi&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/msup&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;mn&gt;4&lt;/mn&gt;&lt;mi&gt;γ&lt;/mi&gt;&lt;mfenced&gt;&lt;mrow&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;msubsup&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;mtext&gt;out&lt;/mtext&gt;&lt;mo&gt;′&lt;/mo&gt;&lt;/msubsup&gt;&lt;/mrow&gt;&lt;/mfenced&gt;&lt;/mrow&gt;&lt;/msqrt&gt;&lt;/mrow&gt;&lt;/mfenced&gt;&lt;/math&gt;&lt;/span&gt; where &lt;span&gt;&lt;math&gt;&lt;mi&gt;γ&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; is a function of E and &lt;span&gt;&lt;math&gt;&lt;mi&gt;f&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt;, and &lt;span&gt;&lt;math&gt;&lt;msubsup&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;mtext&gt;out&lt;/mtext&gt;&lt;mo&gt;′&lt;/mo&gt;&lt;/msubsup&gt;&lt;/math&gt;&lt;/span&gt; is the non-dimensionalized surface temperature. Moreover, the normalized (i.e., non-dimensional) thickness of the stagnant lid, &lt;span&gt;&lt;math&gt;&lt;msup&gt;&lt;mi&gt;L&lt;/mi&gt;&lt;mo&gt;′&lt;/mo&gt;&lt;/msup&gt;&lt;/math&gt;&lt;/span&gt;, can be obtained from a measurement of the non-dimensional surface heat flux once &lt;","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"349 ","pages":"Article 107157"},"PeriodicalIF":2.3,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0031920124000153/pdfft?md5=12d6c0f103726e2f43e8d3d47da8ce61&pid=1-s2.0-S0031920124000153-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140057312","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The onset of anelastic behavior in fine-grained synthetic dunite","authors":"Tongzhang Qu ,&nbsp;Ian Jackson ,&nbsp;Ulrich H. Faul ,&nbsp;Emmanuel C. David","doi":"10.1016/j.pepi.2024.107160","DOIUrl":"10.1016/j.pepi.2024.107160","url":null,"abstract":"<div><p>Micromechanical models suggest that the onset of anelastic relaxation in polycrystalline olivine, critical to interpretation of the seismic wave attenuation and dispersion in the upper mantle, should be a mild dissipation peak caused by elastically accommodated grain-boundary sliding. Such behavior has been tentatively invoked to explain both a short-period shear modulus deficit and a dissipation plateau poorly resolved at 900–700 °C in previous forced-oscillation experiments on fine-grained dunite tested within mild-steel jackets. However, these observations may have been complicated by the austenite to ferrite plus cementite phase transition in the jacket material, compliance associated with interfacial Ni₇₀Fe₃₀ foils, and modeling of the mechanical properties of polycrystalline alumina as control specimen. To investigate the influence of these complications within the experimental setup and provide forced-oscillation data of better quality especially at moderate temperatures, we have conducted further forced-oscillation tests for which we removed the interfacial foils, employed single-crystal sapphire as reference sample, and used alternative jacket materials (stainless steel or copper) which experience no phase transition during the staged cooling. The newly acquired forced-oscillation data, although broadly consistent with the previous results, differ significantly especially in temperature sensitivity, and allow refinement of an appropriate Burgers creep-function model. A mild dissipation peak superimposed on monotonic dissipation background during the onset of anelastic relaxation in dry, melt-free and fine-grained dunite has now been consistently observed at temperatures of ∼950–1050 °C and seismic periods of 1–1000 s. Such a dissipation peak with relaxation strength 0.02 ± 0.01 is attributed to elastically accommodated grain-boundary sliding. The high activation energy (&gt; 600 kJ/mol) of viscoelastic behavior involving both dissipation and related dispersion suggests that grain-boundary diffusion may be limited by interfacial reaction within grain boundaries. The reduced relaxation strength makes it difficult to attribute the oceanic lithosphere-asthenosphere boundary to water-mediated elastically accommodated grain-boundary sliding.</p></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"350 ","pages":"Article 107160"},"PeriodicalIF":2.3,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0031920124000189/pdfft?md5=c802be94068b4d599547a8d3330418ae&pid=1-s2.0-S0031920124000189-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140057192","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The effect of rotatability of measuring directions design on the precision of the determination of the anisotropy of magnetic susceptibility: Mathematical model study","authors":"František Hrouda ,&nbsp;Josef Ježek ,&nbsp;Martin Chadima","doi":"10.1016/j.pepi.2024.107159","DOIUrl":"10.1016/j.pepi.2024.107159","url":null,"abstract":"<div><p>The precision of the measurement of the anisotropy of magnetic susceptibility (AMS) depends, in addition to other factors like accuracy of measurement of directional susceptibility and number of measuring directions, also on the orientation of the measuring design with respect to the specimen's anisotropy. The last factor can be characterized by rotatability coefficient of the measuring design. We investigated through mathematical modelling of measuring process the effect of the rotatability coefficient on the error in the determination of degree of AMS, shape factor and principal directions. The effect is conspicuous in strongly non-rotatable designs with low number of measuring directions. It decreases with increasing rotatability and with increasing number of measuring directions. In designs with high number of directions this effect is small, virtually negligible from the practical point of view.</p></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"349 ","pages":"Article 107159"},"PeriodicalIF":2.3,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140057181","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Three-dimensional magnetotelluric modeling with nontrivial anisotropy by a regularization approach","authors":"Zeqiu Guo ,&nbsp;Hao Dong ,&nbsp;Keke Zhang","doi":"10.1016/j.pepi.2024.107158","DOIUrl":"https://doi.org/10.1016/j.pepi.2024.107158","url":null,"abstract":"<div><p>The regularization approach has been successfully applied to remove spurious solutions in the magnetotelluric (MT) forward problems of isotropic Earth media. However, spurious modes are more likely to occur in numerical solutions of anisotropic media, as electrical anisotropy introduces many more complications to electromagnetic (EM) induction in such media. This study focuses on developing the regularization approach to 3D MT forward problems of anisotropic media, especially those of nontrivial anisotropy. The governing equation is now derived with a conductivity tensor, and an accordingly adapted form of a scaled grad-div term is augmented to regularize the solutions and constrain the divergence-free condition. A new scaling scheme is proposed to cope with the complicated distribution of current densities in nontrivial anisotropy media, and an effective conductivity is approximated by the diagonal elements of the conductivity tensor to formulate the scaling factor. Numerical tests show that, for various models of electrical anisotropy, the regularization approach can effectively enforce the divergence condition and successfully suppress spurious solutions. Therefore, for nontrivial anisotropy media, this approach can also improve the efficiency of the iterative solvers while retaining the accuracy of the solutions. The derivation of the governing equation is based on the MT method. However, this strategy should be generally applicable to other frequency-domain EM methods.</p></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"349 ","pages":"Article 107158"},"PeriodicalIF":2.3,"publicationDate":"2024-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139986976","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical modelling of the 1996 Chimbote-Peru tsunami earthquake (Mw 7.5)","authors":"Cesar Jimenez ,&nbsp;Yuchen Wang","doi":"10.1016/j.pepi.2024.107154","DOIUrl":"10.1016/j.pepi.2024.107154","url":null,"abstract":"<div><p>The earthquake of Chimbote occurred on February 21, 1996 in the northern region of Peru. Despite its relatively small magnitude, it generated a tsunami of 2–3 m height in Chimbote, taking the lives of 12 people. We conducted the signal processing of 31 broadband teleseismic stations, and waveform inversion to obtain the slip distribution and source time function, which indicated a multiple rupture process. The rupture process had a duration of 70 s, a rather high value for a relatively small earthquake. The calculated scalar seismic moment was <span><math><mn>2.19</mn><mo>×</mo><msup><mn>10</mn><mn>20</mn></msup></math></span> Nm, corresponding to a moment magnitude of Mw 7.5. The slip distribution was heterogeneous, with a maximum slip of 8.9 m around the main asperity concentrated in an area of <span><math><mn>30</mn><mo>×</mo><mn>30</mn><mspace></mspace><msup><mi>km</mi><mn>2</mn></msup></math></span>, for an constrained rigidity of <span><math><mn>1.46</mn><mo>×</mo><msup><mn>10</mn><mn>10</mn></msup><mspace></mspace><mi>N</mi><mo>/</mo><msup><mi>m</mi><mn>2</mn></msup></math></span>. We also calculated the vertical coseismic deformation for 45 subfaults, which was used as an initial condition for the tsunami propagation modelling. Simulated tsunami waveforms were calculated for Salaverry (<span><math><msub><mi>H</mi><mi>max</mi></msub><mo>=</mo><mn>0.81</mn></math></span> m), Santa (<span><math><msub><mi>H</mi><mi>max</mi></msub><mo>=</mo><mn>4.62</mn></math></span> m) and Chimbote (<span><math><msub><mi>H</mi><mi>max</mi></msub><mo>=</mo><mn>2.67</mn></math></span> m) tidal stations.</p></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"348 ","pages":"Article 107154"},"PeriodicalIF":2.3,"publicationDate":"2024-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139881810","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of water on the thermoelastic properties of Fe bearing ringwoodite: A first-principles study","authors":"Rabindranath Mondal,&nbsp;Gaurav Shukla,&nbsp;Swastika Chatterjee","doi":"10.1016/j.pepi.2024.107156","DOIUrl":"10.1016/j.pepi.2024.107156","url":null,"abstract":"<div><p>Using first-principles density functional theory (DFT), we model the thermoelastic properties of hydrated ringwoodite (γ-(Fe, Mg)₂SiO₄), a potential water reservoir in the Earth's mantle transition zone (MTZ). Our calculations indicate that hydration, in general, leads to a reduction in the sound wave velocity of ringwoodite. However, increased pressure tends to suppress this reduction. For our 1.56 wt% H₂O containing ringwoodite model, we find that the suppression is so large that at pressure and temperature (P-T) conditions relevant to the lower part of the MTZ the sound wave velocities for the hydrous (1.56 wt% H₂O) ringwoodite become very similar to that of the anhydrous ringwoodite. However, when the water concentration is increased to 3.3 wt%, the pressure-induced suppression of the velocity reduction due to hydration is not so significant. We have given a plausible explanation for the same on the basis of the electronic structure of the hydrous ringwoodite models. We conclude that in the lower part of the MTZ, seismic wave data is sufficiently robust to detect regions of very high-water content (∼3.3 wt%). However, if the water concentration is less than 1.56 wt%, sound wave velocities may not be able to precisely detect the state of hydration of the MTZ.</p></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"348 ","pages":"Article 107156"},"PeriodicalIF":2.3,"publicationDate":"2024-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139889969","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Complexity of the 2016 M 7.8 Kaikōura, New Zealand, earthquake from seismic observation: Inferences of overpressured fluid involvement","authors":"Tomomi Okada ,&nbsp;Miu Matsuno ,&nbsp;Satoshi Matsumoto ,&nbsp;Yuta Kawamura ,&nbsp;Yoshihisa Iio ,&nbsp;Tadashi Sato ,&nbsp;Ayaka Tagami ,&nbsp;Satoshi Hirahara ,&nbsp;Shuutoku Kimura ,&nbsp;Stephen Bannister ,&nbsp;John Ristau ,&nbsp;Martha K. Savage ,&nbsp;Clifford H. Thurber ,&nbsp;Richard H. Sibson","doi":"10.1016/j.pepi.2024.107155","DOIUrl":"https://doi.org/10.1016/j.pepi.2024.107155","url":null,"abstract":"<div><p>The M 7.8 Kaikoura earthquake occurred in the northern South Island of New Zealand on 3 Nov., 2016, involving the rupture of &gt;20 faults. To understand the complexity of the Kaikoura earthquake, details of the fault geometry, seismic velocity distribution, and stress field are necessary. We have undertaken seismic tomography along the c. 200 km length of the rupture zone. Data from both 51 temporary stations and 22 permanent (GeoNet) stations were collected from March 2011 to December 2018.</p><p>The hypocenter of the Kaikoura earthquake and aftershocks near the Kekerengu fault locate along lineaments where seismic velocity changes laterally in the epicentral region. In the uppermost crust, lower velocities occur beneath the Emu Plain and Cape Campbell. A higher velocity region near Kaikoura may have acted as a barrier that prevented eastward rupture from the hypocenter and led to the complex fault distribution in this area. These complexities in the seismic velocity structure may relate to the multi-segment rupture character of the Kaikoura earthquake. Spatial correlations between rupture areas and high Vp/Vs suggest the involvement of overpressured fluid in the nucleation and propagation of rupture segments, which is also supported by the reactivation of unfavourably oriented strike-slip ruptures, many lying at c.70° to the regional maximum compressive stress trajectories.</p></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"348 ","pages":"Article 107155"},"PeriodicalIF":2.3,"publicationDate":"2024-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S003192012400013X/pdfft?md5=c5526cb1a66b910c0d456f53dcf3d778&pid=1-s2.0-S003192012400013X-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139733025","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Southeastward extrusion of the Tibetan Plateau limited by the strong Emeishan large igneous province from earthquake surface wave tomography","authors":"Yuanyuan V. Fu ,&nbsp;Lun Li ,&nbsp;Junwei Ma ,&nbsp;Nannan Sun","doi":"10.1016/j.pepi.2024.107153","DOIUrl":"https://doi.org/10.1016/j.pepi.2024.107153","url":null,"abstract":"<div><p>Active deformation is ongoing in the southeastern margin of the Tibetan Plateau due to the collision of the Indian and Eurasian continents. While large-scale motion of the surface occurs, the nature of deformation at depth remains unresolved. We construct new lithospheric seismic anisotropic (radially and azimuthally) and shear-wave velocity models using fundamental-mode Rayleigh- and Love-wave phase velocity at periods of 20–100 s obtained from the ChinArray experiment to constrain the deformation style of the crust and upper mantle in the southeastern margin of the Tibetan Plateau. The results show that the uppermost mantle (Moho-90 km) underneath the Tibetan Plateau and northwestern part of the western Yangtze block are characterized with NE-SW oriented azimuthal anisotropy, prominent slow velocity and negative radial anisotropy (V_SH &lt; V_SV). We interpret that this seismic pattern reflects the southeastward extrusion of the Tibetan uppermost mantle that may thermally erode the northwestern edge and result in the vertically coherent fabric due to the barriers of the left strong Emeishan large igneous province (i.e., south of the western Yangtze block) dominated by the high shear wave velocities. Low velocity anomaly, N-S trending azimuthal anisotropy, and negative radial anisotropy in the uppermost mantle beneath the eastern Yangtze block are most probably associated with vertical migration of hot mantle material from the lithosphere delamination and/or a branch of the Hainan plume.</p></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"348 ","pages":"Article 107153"},"PeriodicalIF":2.3,"publicationDate":"2024-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139733024","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Constraining Earth's mantle rheology with Love and Shida numbers at the M2 tidal frequency","authors":"Dargilan Oliveira Amorim ,&nbsp;Tamara Gudkova","doi":"10.1016/j.pepi.2024.107144","DOIUrl":"10.1016/j.pepi.2024.107144","url":null,"abstract":"<div><p>We use measurements of Earth's tidal response at the <span><math><msub><mi>M</mi><mn>2</mn></msub></math></span><span> frequency to constrain the rheology of its mantle. The viscoelasticity<span> and anelasticity of the planet are modeled with an Andrade rheology that depends on two parameters: </span></span><span><math><mi>α</mi></math></span> and <span><math><mi>ζ</mi></math></span>. In this paper, we propose an improved algorithm to compute Earth's tidal deformation. Its Love and Shida numbers <span><math><msub><mi>k</mi><mn>2</mn></msub></math></span>, <span><math><msub><mi>h</mi><mn>2</mn></msub></math></span>, <span><math><msub><mi>k</mi><mn>3</mn></msub></math></span> and <span><math><msub><mi>l</mi><mn>2</mn></msub></math></span> as well as the tidal lag <span><math><mi>ϵ</mi></math></span> were calculated for two viscosity profiles and for a wide range of values of <span><math><mi>α</mi></math></span> and <span><math><mi>ζ</mi></math></span>. By comparing our results with geodetic measurements we obtain the range of values of <span><math><mi>α</mi></math></span> and <span><math><mi>ζ</mi></math></span> that successfully describes Earth's viscoelastic behavior. Values of <span><math><mi>ζ</mi></math></span> as high as <span><math><msup><mn>10</mn><mn>5</mn></msup></math></span> can not be excluded. For <span><math><mi>ζ</mi><mo>=</mo><mn>1</mn></math></span>, <span><math><mi>α</mi></math></span> should be in the range from 0.19 to 0.33, while for a <span><math><mi>ζ</mi><mo>=</mo><msup><mn>10</mn><mn>5</mn></msup></math></span>, <span><math><mi>α</mi></math></span><span> is most likely between 0.11 and 0.17. We believe that a similar rheology should be used in geophysical models of other rocky planets and satellites. The obtained results are mostly representative of the lower mantle.</span></p><p>We have also shown that for several combinations of the two parameters <span><math><mi>α</mi></math></span> and <span><math><mi>ζ</mi></math></span> we could obtain nearly identical values of Earth's <span><math><mi>ℜ</mi><mfenced><msub><mi>k</mi><mn>2</mn></msub></mfenced></math></span>, <span><math><mi>ℜ</mi><mfenced><msub><mi>h</mi><mn>2</mn></msub></mfenced></math></span>, <span><math><mi>ℜ</mi><mfenced><msub><mi>l</mi><mn>2</mn></msub></mfenced></math></span> and <span><math><mi>ℜ</mi><mfenced><msub><mi>k</mi><mn>3</mn></msub></mfenced></math></span> with considerably different values of the associated tidal lag. This shows that the approach of always setting <span><math><mi>ζ</mi><mo>=</mo><mn>1</mn></math></span> might be too simplistic and an Andrade rheology with two free parameters is needed to constrain both the real and imaginary parts of Love and Shida numbers.</p></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"347 ","pages":"Article 107144"},"PeriodicalIF":2.3,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139554240","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}