Journal of Geophysical Research: Solid Earth最新文献

{"title":"Revisiting Slip Deficit Rates and Its Insights Into Large and Slow Earthquakes at the Nankai Subduction Zone","authors":"Raymundo Plata-Martinez,&nbsp;Takeshi Iinuma,&nbsp;Fumiaki Tomita,&nbsp;Yasuyuki Nakamura,&nbsp;Takuya Nishimura,&nbsp;Takane Hori","doi":"10.1029/2023JB027942","DOIUrl":"10.1029/2023JB027942","url":null,"abstract":"<p>The Nankai subduction zone presents significant seismic and tsunami risks, given its historical earthquakes exceeding magnitude 8 and the expectations of similar future events. Slow earthquakes, common at the shallow and deep plate interface, result from different frictional properties linked to interplate slip deficit accumulation. This study estimates slip deficit rates at the Nankai subduction zone using land and ocean-bottom geodetic data. Previous estimates encountered limitations, often smoothing slip deficits, omitting observational error differences between ocean-floor and land data, and relying on homogeneous structure models. To address these issues, we employ a novel trans-dimensional reversible jump Markov Chain Monte Carlo algorithm. This approach dynamically adjusts slip parameters, accommodating data resolution and producing a flexible slip distribution without predetermined spatial constraints. Additionally, it automatically weights data for observational errors and integrates elastic Green functions from a 3D structure of the Nankai region. Our results provide a finer, heterogeneous slip distribution, improving estimates in inland regions. However, limitations remain offshore in areas with sparse data. We revised the spatial distribution of Nankai slow earthquakes and confirmed a good agreement with intermediate slip deficit rates, identifying coupled and uncoupled regions. High slip deficit rates align with rupture areas of historic large earthquakes. Slow earthquakes occur at frictionally weak plate interfaces, and shallow slow earthquakes may result from subducting relief heterogeneities with important pore fluid pressure effects. We introduce an updated distribution of slip deficit rates for the Nankai subduction zone, considering observed slip deficit rates and the fast and slow earthquake occurrence.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"129 12","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2023JB027942","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142857724","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Experimental Investigation on the Brittle-Ductile Transition of Natural Mafic Granulite","authors":"Jiaxiang Dang,&nbsp;Yongsheng Zhou,&nbsp;David P. Dobson,&nbsp;Thomas M. Mitchell","doi":"10.1029/2024JB030065","DOIUrl":"10.1029/2024JB030065","url":null,"abstract":"&lt;p&gt;Semi-brittle and plastic deformation behaviors of mafic granulite are significant for evaluating characteristics of ductile zones in the lower crust region and the rheological strength of the lower crust. Axial compression experiments were carried out in this study with natural mafic granulite collected from the North China Craton, using a gas medium apparatus at 950–1,150°C and 300 MPa with strain up to 17%. The samples are composed of 57 vol.% Plagioclase, 19 vol.% Clinopyroxene, 20 vol.% Orthopyroxene, and 4 vol.% magnetite and ilmentite. The mean grain size is 300–700 μm. The bulk structural water content is 891 ± 399 wt ppm. At 950–1,000°C, the samples were brittly broken by scattered cracks and localized fault zones. At 1,050–1,075°C, the samples were deformed by ductile shear zones that broadened with increasing temperature, the deformation behavior is characterized by a steady-state semi-brittle creep; mechanic data yield a flow law of &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mover&gt;\u0000 &lt;mi&gt;ε&lt;/mi&gt;\u0000 &lt;mo&gt;˙&lt;/mo&gt;\u0000 &lt;/mover&gt;\u0000 &lt;mo&gt;=&lt;/mo&gt;\u0000 &lt;msup&gt;\u0000 &lt;mn&gt;10&lt;/mn&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mn&gt;6.0&lt;/mn&gt;\u0000 &lt;mo&gt;±&lt;/mo&gt;\u0000 &lt;mn&gt;0.3&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msup&gt;\u0000 &lt;msup&gt;\u0000 &lt;mtext&gt;MPa&lt;/mtext&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;mn&gt;5.8&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msup&gt;\u0000 &lt;msup&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msup&gt;\u0000 &lt;mi&gt;s&lt;/mi&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;mn&gt;1&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msup&gt;\u0000 &lt;mi&gt;σ&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mn&gt;5.8&lt;/mn&gt;\u0000 &lt;mo&gt;±&lt;/mo&gt;\u0000 &lt;mn&gt;0.1&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msup&gt;\u0000 &lt;mi&gt;exp&lt;/mi&gt;\u0000 &lt;mfenced&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;mfrac&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mn&gt;651&lt;/mn&gt;\u0000 &lt;mo&gt;±&lt;/mo&gt;\u0000 &lt;mn&gt;68&lt;/mn&gt;\u0000 &lt;mtext&gt;kJ&lt;/mtext&gt;\u0000 &lt;mo&gt;/&lt;/mo&gt;\u0000 &lt;mtext&gt;mol&lt;/mtext&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;R&lt;/mi&gt;\u0000 &lt;mi&gt;T&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/mfrac&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/mfenced&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $dot{varepsilon ","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"129 12","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142857727","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Orientation Piezometry: Methods for Quantifying Stress From the Compositions and Orientations of Multicomponent Minerals","authors":"Benjamin L. Hess,&nbsp;Jay J. Ague","doi":"10.1029/2024JB030113","DOIUrl":"10.1029/2024JB030113","url":null,"abstract":"<p>Mineral chemistry records the pressure and temperature conditions of lithospheric processes. Active tectonic margins, however, are subjected to non-hydrostatic stresses wherein stress magnitudes vary directionally, and the impact of non-hydrostatic stress on mineral chemistry is uncertain. The work of materials scientists F. Larché and J. Cahn provides a framework for quantifying how stress affects mineral chemistry. Crystallographically and mechanically anisotropic, multicomponent minerals will have different compositions as a function of their orientation under a fixed stress meaning that grain-to-grain compositional variation can be used to estimate stress. We develop two “orientation piezometry” methods that use the chemistry and orientations of multicomponent, anisotropic minerals to estimate stress. The first method uses chemistry and orientation (“coupled orientation piezometry”) whereas the second method uses composition alone (“decoupled orientation piezometry”). We apply the methods to clinopyroxene and feldspar solid solutions using synthetic data sets. The first method determines the full stress tensor whereas the second method can only determine the differential stress magnitude unless additional a priori information is specified. Plausible scenarios for orientation piezometry include minerals undergoing diffusion creep, recrystallized grains formed during dislocation creep, and minerals grown statically under stress. Preliminary application of the decoupled piezometer to the famous eclogite facies shear zones on Holsnøy, Norway, suggests differential stresses in the range of 300–900 MPa, broadly consistent with previous estimates from the area. Thus, orientation piezometry techniques may provide valuable constraints on geodynamic processes and insights into long-standing geological problems such as the relationship between pressure and depth.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"129 12","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142857726","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Global Combination of Geodetic Techniques at the Observation Level: New Perspectives on the Terrestrial Reference Frame","authors":"B. Haines,&nbsp;W. Bertiger,&nbsp;S. Desai,&nbsp;M. Ellmer,&nbsp;M. Heflin,&nbsp;D. Kuang,&nbsp;G. Lanyi,&nbsp;C. Naudet,&nbsp;A. Peidou,&nbsp;P. Ries,&nbsp;A. Sibois,&nbsp;X. Wu","doi":"10.1029/2024JB029527","DOIUrl":"10.1029/2024JB029527","url":null,"abstract":"<p>We describe the development and assessment of a new terrestrial reference frame (TRF) based on a combination of geodetic techniques at the observation level over the period 2010–2022. Included in the solution are observations from the Global Positioning System (GPS), Satellite Laser Ranging (SLR) and Very Long Baseline Interferometry (VLBI). A key feature of our solution strategy is the use of space ties in low-Earth orbit to connect SLR to GPS. Though the resulting TRF solution is based on only 12.6 years of data, it is competitive with the international (ITRF2020) standard in terms of fundamental frame parameters (origin and scale) and their temporal evolution, both linear and seasonal. The relative rates of origin (3D) and scale (at Earth's surface) are 0.2 mm <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msup>\u0000 <mtext>yr</mtext>\u0000 <mrow>\u0000 <mo>−</mo>\u0000 <mn>1</mn>\u0000 </mrow>\u0000 </msup>\u0000 </mrow>\u0000 <annotation> ${text{yr}}^{-1}$</annotation>\u0000 </semantics></math> and 0.1 mm <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msup>\u0000 <mtext>yr</mtext>\u0000 <mrow>\u0000 <mo>−</mo>\u0000 <mn>1</mn>\u0000 </mrow>\u0000 </msup>\u0000 </mrow>\u0000 <annotation> ${text{yr}}^{-1}$</annotation>\u0000 </semantics></math> respectively. Absolute scale and 3D origin (at epoch 2015.0) both differ by 2–3 mm. In addition to station positions and velocities, our combined solution includes Earth orientation parameters (EOP), low-degree zonal coefficients (J2 and J3) of the geopotential and precise orbit solutions for all participating satellites (GPS, GRACE and GRACE Follow-on tandems, Jason 2 and 3, and LAGEOS 1 and 2). We discuss potential benefits of our solution strategy and characterize the impacts of our new TRF on estimates of geocenter motion and sea level change from satellite altimetry.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"129 12","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JB029527","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142841841","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Accretionary Wedge, Arc Magmatism and Fluid Migration in Northern Sumatra: Insight From Seismic Attenuation Tomography","authors":"Debiao Liu,&nbsp;Zewei Wang,&nbsp;Dapeng Zhao,&nbsp;Hao Hu,&nbsp;Rui Gao","doi":"10.1029/2024JB029777","DOIUrl":"10.1029/2024JB029777","url":null,"abstract":"<p>The first three-dimensional (3-D) P and S wave attenuation (Qp and Qs) tomography of the crust and upper mantle of the northern Sumatra subduction zone is determined. We adopt an improved calculation scheme to precisely measure attenuation factor <i>t</i>* values from velocity amplitude spectral ratios among different stations that recorded the same earthquake. Our tomographic results show that the forearc accretionary wedge in Sumatra exhibits a significant high-attenuation (low-Q) zone along the trench. The seismic attenuation characteristics of the forearc accretionary wedge are probably influenced by variations in temperature and water content. The middle and upper crust beneath active arc volcanoes shows low-Q and high-Qp/Qs, while the lower crust exhibits less low-Q and low-Qp/Qs, probably reflecting hot volcanic roots with different water saturations from the upper to lower crust. Beneath the Toba volcano that had a super-eruption ∼74,000 years ago, a distinct low-Qp/Qs zone is revealed, which may reflect a transport pathway of fluids and/or local melts ascending from a slab window. The subducting Indo-Australian slab beneath the forearc island chain exhibits a low-Q and low-Qp/Qs belt, reflecting a moderate water saturation probably associated with backthrust faulting. High-Q and high-Qp/Qs zones appear along the slab surface, reflecting large amounts of fluids releasing from the slab dehydration, which may increase pore pressure and cause intense intraslab seismicity.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"129 12","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142825175","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Combining Visible- and Infrared-Wavelength Observations With Numerical Modeling to Describe Vulcanian Eruption Plumes at Sabancaya, Peru","authors":"R. Simionato,&nbsp;P. A. Jarvis,&nbsp;E. Rossi,&nbsp;A. Fries,&nbsp;M. Pistolesi,&nbsp;R. Aguilar,&nbsp;C. Bonadonna","doi":"10.1029/2024JB029326","DOIUrl":"10.1029/2024JB029326","url":null,"abstract":"&lt;p&gt;Sabancaya volcano (Peru), is a stratovolcano in the Central Volcanic Zone of the Andes. Since November 2016, it has been in constant activity, marked by daily multiple Vulcanian explosions. In this contribution, we first characterize the plumes generated by the explosions using visible- and infrared-wavelength imagery, describing plume morphologies and quantifying rise rates. Through an analysis of plume morphology and rise rates, we find that plumes fall on a continuum between two end-member classifications. Class A plumes are characterized by an amorphous head containing multiple vortices which may combine to form a vortex ring. These plumes have higher initial velocities (generally &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;≳&lt;/mo&gt;\u0000 &lt;mn&gt;10&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $gtrsim 10$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; m &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msup&gt;\u0000 &lt;mi&gt;s&lt;/mi&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;mn&gt;1&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msup&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${mathrm{s}}^{-1}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; and up to 40 m &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msup&gt;\u0000 &lt;mi&gt;s&lt;/mi&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;mn&gt;1&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msup&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${mathrm{s}}^{-1}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;) which monotonically decrease as the plume rises. Conversely, class B plumes have narrow, cylindrical morphologies and lack large vortical structures in the head. They have smaller initial velocities (&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;≲&lt;/mo&gt;\u0000 &lt;mn&gt;12&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $lesssim 12$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; m &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msup&gt;\u0000 &lt;mi&gt;s&lt;/mi&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;mn&gt;1&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msup&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${mathrm{s}}^{-1}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;) and, after an initial rise, undergo stagnation followed by a short acceleration in rise velocity, before slowing down again. Secondly, we use a numerical model to invert our observations for eruptive source conditions, including the initial temperature, gas mass fraction and bulk density, as","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"129 12","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JB029326","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142825176","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Seasonal Snow Cycles and Their Possible Influence on Seismic Velocity Changes and Eruptive Activity at Ruapehu Volcano, New Zealand","authors":"Alexander S. Yates,&nbsp;Corentin Caudron,&nbsp;Aurélien Mordret,&nbsp;Philippe Lesage,&nbsp;Virginie Pinel,&nbsp;Thomas Lecocq,&nbsp;Craig A. Miller,&nbsp;Oliver D. Lamb,&nbsp;Nicolas Fournier","doi":"10.1029/2024JB029568","DOIUrl":"10.1029/2024JB029568","url":null,"abstract":"<p>Understanding volcanic eruption triggers is critical toward anticipating future activity. While internal magma dynamics typically receive more attention, the influence of external processes remains less understood. In this context, we explore the relationship between seasonal snow cycles and eruptive activity at Ruapehu, New Zealand. This is motivated by apparent seasonality in the eruptive record, where a higher than expected proportion of eruptions (post-1960) occur in spring (including the two previous eruptions of 2006 and 2007). Employing recent advancements in passive seismic interferometry, we compute sub-surface seismic velocity changes between 2005 and 2009 using the cross-wavelet transform approach. Stations on the volcano record a higher velocity in winter, closely correlated with the presence of snow. Inverting for depth suggests these changes occur within the upper 300 m. Notably, we observe that the timing of the previous two eruptions coincides with a period associated with an earlier velocity decrease at approximately 200–300 m depth relative to the surface. Reduced water infiltration (as precipitation falls as snow) is considered a likely control of seasonal velocities, while modeling also points to a contribution from snow-loading. We hypothesize that this latter process may play a role toward explaining seasonality in the eruptive record. Our findings shed light on the complex interactions between volcanoes and external environmental processes, highlighting the need for more focused research in this area. Pursuing this line of inquiry has significant implications toward improved risk and hazard assessments at not just Ruapehu, but also other volcanoes globally that experience seasonal snow cover.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"129 12","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JB029568","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142820929","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Melting of B1-Phase MgO From Simultaneous True Radiative Shock Temperature and Sound Speed Measurements to 250 GPa on Samples Preheated to 2300 K","authors":"O. V. Fat’yanov,&nbsp;P. D. Asimow","doi":"10.1029/2024JB029137","DOIUrl":"10.1029/2024JB029137","url":null,"abstract":"&lt;p&gt;To refine the melting curve, equation of state, and physical properties of MgO we performed plate impact experiments spanning &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;∼&lt;/mo&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${sim} $&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;170–250 GPa on &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;&lt;&lt;/mo&gt;\u0000 &lt;mn&gt;100&lt;/mn&gt;\u0000 &lt;mo&gt;&gt;&lt;/mo&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${&lt; } 100 &gt; $&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; MgO single crystals, preheated to 2300 K. A controlled thermal gradient in &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;∼&lt;/mo&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${sim} $&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;20 mm long samples enabled radiative temperature (&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;±&lt;/mo&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $pm $&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;3%–4%) and rarefaction overtake observations (yielding sound speed &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;±&lt;/mo&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $pm $&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;2%) close to the hot Mo driver with a free surface below &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;∼&lt;/mo&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${sim} $&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;2000 K that minimized evaporation. Ta flyers were launched by two-stage light-gas gun up to 7.6 km/s and sample radiance was recorded with a 6-channel (500–850 nm) pyrometer. Shock front reflectivity was measured at 198 and 243 GPa using &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;∼&lt;/mo&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${sim} $&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;50/50 sapphire beam-splitters. Most experiments show monotonic increases of shock temperature with pressure, from (168 GPa, 7100 K) to (243 GPa, 9400 K), in good agreement with predictions of our MgO B1 phase equation of state. Measured sound speeds are parallel to but &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;∼&lt;/mo&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${sim} $&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;10% higher than model predictions for bulk sound speed of solid B1 MgO, confirming ductile behavior of preheated MgO. Two experiments, at 238 and 246 GPa, showed anomalously low shock temperature and sound speed, suggesting melting. Using reported MgO melting data up to 120 GPa and our data at 232–246 GPa, we constructed a maximum-likelihood Simon-Glatzel fit. At Earth's core-mantle boundary pressure (135 GPa), our best-fit interpo","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"129 12","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142816028","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Microstructural and Micromechanical Evolution of Olivine Aggregates During Transient Creep","authors":"Harison S. Wiesman,&nbsp;Thomas Breithaupt,&nbsp;David Wallis,&nbsp;Lars N. Hansen","doi":"10.1029/2024JB029812","DOIUrl":"10.1029/2024JB029812","url":null,"abstract":"<p>To examine the microstructural evolution that occurs during transient creep, we deformed samples of polycrystalline olivine to different strains that spanned the initial transient deformation. Two sets of samples with different initial grain sizes of 5 μm and 20 μm were deformed in torsion at <i>T</i> = 1,523 K, <i>P</i> = 300 MPa, and a constant shear strain rate of 1.5 × 10⁻⁴ s⁻¹, during which both sets of samples experienced strain hardening. We characterized the microstructures at the end of each experiment using high-angular resolution electron backscatter diffraction (HR-EBSD) and dislocation decoration. In the coarse-grained samples, dislocation density increased from 1.5 × 10¹¹ m⁻² to 3.6 × 10¹² m⁻² with strain. Although the same final dislocation density was reached in the fine-grained samples, it did not vary significantly at small strains, potentially due to concurrent grain growth during deformation. In both sets of samples, HR-EBSD analysis revealed that intragranular stress heterogeneity increased in magnitude with strain and that elevated stresses are associated with regions of high geometrically necessary dislocation density. Further analysis of the stresses and their probability distributions indicate that the stresses are imparted by dislocations and cause long-range elastic interactions among them. These characteristics indicate that dislocation interactions were the primary cause of strain hardening during transient creep in our samples. A comparison of the results to the predictions of three recent models reveals that the models do not correctly predict the evolution in stress and dislocation density with strain in our experiments due to a lack of previous such data in their calibrations.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"129 12","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JB029812","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142816029","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Permeability Development During Fault Growth and Slip in Granite","authors":"Franciscus M. Aben,&nbsp;Ado Farsi,&nbsp;Nicolas Brantut","doi":"10.1029/2024JB029057","DOIUrl":"10.1029/2024JB029057","url":null,"abstract":"<p>In tight crystalline rocks faults are known to be substantially more hydraulically conductive than the rock matrix. However, most of our knowledge relies on static measurements, or before/after failure data sets. The spatio-temporal evolution of the permeability field during faulting remains unknown. Here, we determine at which stage of faulting permeability changes most, and the degree of permeability heterogeneity along shear faults. We conducted triaxial deformation experiments in intact Westerly granite, where faulting was stabilized by monitoring acoustic emission rate. At repeated stages during deformation and faulting we paused deformation and imposed macroscopic fluid flow to characterize the overall permeability of the material. The pore pressure distribution was measured along the prospective fault to estimate apparent hydraulic transmissivity, and propagation of the macroscopic shear fault was monitored by locating acoustic emissions. We find that average permeability increases dramatically (by two orders of magnitude) with increasing deformation up to peak stress, where the fault is not yet through-going. Post-peak stress, overall permeability increases by a factor of three. However, at this stage we observed local heterogeneities in permeability by up to factors of eight, ascribed to a partially connected fracture network. This heterogeneity decreases with fault completion at residual shear stress. With further slip on the newly formed fault, the average hydraulic transmissivity remains mostly stable. Our results show that permeability enhancement during shear rupture mostly occurs ahead of the rupture tip, and that strongly heterogeneous permeability patterns are generated in the fault cohesive zone due to partial fracture connectivity.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"129 12","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JB029057","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142816465","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}