Effect of pressure on temperature measurements using WRe thermocouple and its geophysical impact
Publication date: Available online 12 November 2019Source: Physics of the Earth and Planetary InteriorsAuthor(s): Yu Nishihara, Shunta Doi, Sho Kakizawa, Yuji Higo, Yoshinori TangeAbstractOur understanding of the Earth's interior strongly depends on the physical and chemical properties of the Earth's constituent materials, which have been determined using high-pressure/high-temperature experiments involving thermocouples. Thus, knowledge of the pressure effect on the thermocouple electromotive force (EMF) is indispensable for an accurate understanding of the Earth's interior. We have determined the effect of pressure on a ...
Source: Physics of the Earth and Planetary Interiors - November 13, 2019 Category: Physics Source Type: research

Structural heterogeneity and megathrust earthquakes in Southwest Japan
In this study, we present 3-D high-resolution P and S wave velocity and Poisson's ratio images of the Nankai subduction zone, which are determined using a large number of high-quality arrival-time data of well-located onshore and offshore local earthquakes. The obtained seismic images, as well as residual topography and gravity anomalies, show similar structures in both the upper and lower plates above and below the rupture zones of the 1944 Tonankai earthquake (M 8.1), the 1946 Nankai earthquake (M 8.3), and the 1968 Hyuganada earthquake (M 7.5). These results indicate that the nucleation and rupture processes of these me...
Source: Physics of the Earth and Planetary Interiors - November 12, 2019 Category: Physics Source Type: research

How far does a subduction wedge follow lubrication dynamics?
Publication date: Available online 9 November 2019Source: Physics of the Earth and Planetary InteriorsAuthor(s): Giridas Maiti, Nibir MandalAbstractApplications of the lubrication dynamics in subduction zones generally assume very small wedge taper angles (α 
Source: Physics of the Earth and Planetary Interiors - November 9, 2019 Category: Physics Source Type: research

Investigating the strength and trend of seismic anisotropy in the western part of Makran subduction zone and southeast of Iran
Publication date: Available online 6 November 2019Source: Physics of the Earth and Planetary InteriorsAuthor(s): Saeid Rahimzadeh, Ali Moradi, Ayoub KavianiAbstractThe Makran subduction zone, located in southeastern Iran and southern Pakistan, extends approximately 900 km along the Eurasian-Arabian plate boundary, where the Arabian oceanic plate subducts beneath the Eurasian plate. Using broadband seismic data recorded in the western part of Makran in the southeast of Iran, seismic anisotropy was studied to better understand geodynamic processes of this subduction zone. We analyzed shear wave splitting of core-refracted ...
Source: Physics of the Earth and Planetary Interiors - November 8, 2019 Category: Physics Source Type: research

Simultaneous tomography of all periods in surface wave analysis
Publication date: Available online 7 November 2019Source: Physics of the Earth and Planetary InteriorsAuthor(s): Najmieh Mohammadi, Ali Gholami, Habib Rahimi, Abdelkrim AoudiaAbstractTwo dimensional surface wave travel time tomography is one of the most practical methods to image the lateral variation of phase/group velocity. In practice, local dispersion curves are reconstructed by performing 2-D inversion of travel times for a series of periods separately. Although 2-D inversion is numerically efficient, it does not consider the dependency between periods and thus can lead to a suboptimal phase/group velocity. To address...
Source: Physics of the Earth and Planetary Interiors - November 8, 2019 Category: Physics Source Type: research

Editorial Board
Publication date: November 2019Source: Physics of the Earth and Planetary Interiors, Volume 296Author(s): (Source: Physics of the Earth and Planetary Interiors)
Source: Physics of the Earth and Planetary Interiors - November 6, 2019 Category: Physics Source Type: research

New insights into seismic absorption imaging
Publication date: Available online 1 November 2019Source: Physics of the Earth and Planetary InteriorsAuthor(s): Panayiota Sketsiou, Ferdinando Napolitano, Aristides Zenonos, Luca De SienaAbstractIn recent years, attenuation has been used as a marker for source and dynamic Earth processes due to its higher sensitivity to small variations of lithospheric properties compared to seismic velocity. From seismic hazard analysis to oil and gas exploration and rock physics, many fields need a better reconstruction of energy absorption, a constituent of seismic attenuation generally considered a reliable marker of fluid saturation ...
Source: Physics of the Earth and Planetary Interiors - November 3, 2019 Category: Physics Source Type: research

Moment rate of the 2018 Gulf of Alaska earthquake
Publication date: Available online 1 November 2019Source: Physics of the Earth and Planetary InteriorsAuthor(s): Stefano Santini, Michele DragoniAbstractThe 2018 Gulf of Alaska earthquake (Mw 7.9) occurred in a region of the Pacific plate southwest of the Alaskan subduction zone. The earthquake was a strike-slip event, with the hypocenter located at a depth of about 25 km and a seismic moment equal to 0.96 × 1021 Nm. Two observed moment rates have been obtained by the Geoscope Observatory, France, and by the United States Geological Survey (USGS). Both of them can be interpreted as due to the failure of two asper...
Source: Physics of the Earth and Planetary Interiors - November 1, 2019 Category: Physics Source Type: research

Importance of later phases in seismic tomography
Publication date: November 2019Source: Physics of the Earth and Planetary Interiors, Volume 296Author(s): Dapeng ZhaoAbstractSeismic tomography is a powerful tool for mapping the three-dimensional structure of the Earth's interior. Tomographic images obtained in the past four decades have greatly improved our understanding of the Earth's heterogeneous structure and dynamics, which signify a revolution in Earth sciences. Most of the tomographic models are determined using the first P and S wave data generated by local earthquakes and/or teleseismic events. Five global seismic discontinuities exist in the Earth, including th...
Source: Physics of the Earth and Planetary Interiors - November 1, 2019 Category: Physics Source Type: research

Disparate behaviour of deformation patterns beneath northeast Indian lithosphere inferred from shear wave splitting analysis
Publication date: Available online 30 October 2019Source: Physics of the Earth and Planetary InteriorsAuthor(s): Debasis D. Mohanty, Poulommi MondalAbstractNew shear wave splitting measurements are obtained from the North East Indian region utilizing the core refracted PKS/SKS/SKKS phases, suggesting the region as more complex and anisotropic in nature. The splitting parameters namely time delays (δt) and fast polarization directions (ϕ) are computed at nine stations and the results are found to be more consistent with the geologic/tectonic structures and present mantle deformation patterns under this particular reg...
Source: Physics of the Earth and Planetary Interiors - October 31, 2019 Category: Physics Source Type: research

Effects of Coulomb stress change on Mw > 6 earthquakes in the Caucasus region
Publication date: December 2019Source: Physics of the Earth and Planetary Interiors, Volume 297Author(s): Bahruz Ahadov, Shuanggen JinAbstractCoulomb stress variations may trigger earthquakes, while the stress transfer process is not clear. In this paper, Coulomb stress changes are investigated for the sequences of strong earthquakes in the Caucasus region, which followed the 1988 Mw6.8 in Spitak, the 1991 Mw6.9 in Racha and the 2000 Mw6.2 in Baku. Our results show that the mainshocks induced variations in the stress field where most of the seismic events occurred. Coulomb stress increases 2 bars corresponding nearly to ...
Source: Physics of the Earth and Planetary Interiors - October 31, 2019 Category: Physics Source Type: research

Two-stage modeling of Strombolian-type eruptions and quantification of the model parameters: Insight from the seismic and acoustic signals
Publication date: December 2019Source: Physics of the Earth and Planetary Interiors, Volume 297Author(s): Vyacheslav M. Zobin, Jean Battaglia, William Melson, Yasuaki SudoAbstractThe seismic signals of majority Strombolian explosions show a two-phase structure that may be the result of a two-stage explosive eruption. We quantify the parameters of two proposed stages of Strombolian eruptions at volcanoes Arenal, Aso and Yasur using 193 seismic records and 18 acoustic signals and considering that the first stage of eruption represents the seismically active process of the gas slug expansion and ascent (GSEA) in the conduit a...
Source: Physics of the Earth and Planetary Interiors - October 29, 2019 Category: Physics Source Type: research

Attenuation of high frequency body waves in the crust of western Tibet
Publication date: Available online 28 October 2019Source: Physics of the Earth and Planetary InteriorsAuthor(s): Rahul Biswas, Chandrani SinghAbstractThe attenuation characteristics of western Tibet have been analyzed by estimating the seismic attenuation parameters (Qp−1 and Qs−1) at five different central frequencies (1.5, 3, 6, 12 and 18 Hz). The extended coda normalization method has been used on 469 three component local earthquakes which are recorded at Y2 network of broadband stations deployed in western Tibet during 2007-2011 years. We have estimated the frequency dependent Qp−1 and Qs−1 val...
Source: Physics of the Earth and Planetary Interiors - October 28, 2019 Category: Physics Source Type: research

Crustal structure and lateral variations in Moho beneath the Delhi fold belt, NW India: Insight from gravity data modeling and inversion
Publication date: December 2019Source: Physics of the Earth and Planetary Interiors, Volume 297Author(s): Divyanshu Dwivedi, Ashutosh Chamoli, Anand K. PandeyAbstractThe Proterozoic Delhi fold belt (DFB) in NW India shows a prominent NNE-SSW trending gravity high, but its northward extension beneath Gangetic alluvium lack understanding. We model the gravity anomaly using radially averaged power spectrum, depth from extreme points (DEXP) method, wavelength filtering, 3D structural inversion to constrain crustal structure of the DFB. The radially averaged power spectrum analysis suggests three interfaces and the DEXP method ...
Source: Physics of the Earth and Planetary Interiors - October 27, 2019 Category: Physics Source Type: research

Extremely young melt infiltration of the sub-continental lithospheric mantle
Publication date: Available online 23 October 2019Source: Physics of the Earth and Planetary InteriorsAuthor(s): Simon Turner, Michael Turner, Bernard Bourdon, Kari Cooper, Don PorcelliAbstractIt has long been inferred that mantle metasomatism and the incompatible element enrichment of the continents both require movement of melts formed by very low degree melting of the mantle. Yet establishing the presence of these melts and whether this process is on-going and continuous, or spatially and temporally restricted, has proved difficult. Here we report large U-Th-Ra disequilibria in metasomatised, mantle xenoliths erupted in...
Source: Physics of the Earth and Planetary Interiors - October 25, 2019 Category: Physics Source Type: research

Nonlinear dynamics of crustal blocks and faults and earthquake occurrences in the Transcaucasian region
Publication date: Available online 23 October 2019Source: Physics of the Earth and Planetary InteriorsAuthor(s): Inessa Vorobieva, Alik Ismail-Zadeh, Alexander GorshkovAbstractThe Caucasus is a part of ongoing collision of the Arabian and Eurasian plates, where moderate to strong earthquakes caused significant losses of lives and livelihood in the past. To better understand seismic hazard in the region, we develop a model of block-and-fault dynamics for Transcaucasia, the largest part of the Caucasus to the south of the Greater Caucasus Mountains, to simulate regional earthquakes. The model structure is developed by employ...
Source: Physics of the Earth and Planetary Interiors - October 25, 2019 Category: Physics Source Type: research

Crustal and uppermost mantle structure across the Lower Yangtze region and its implications for the late Mesozoic magmatism and metallogenesis, eastern South China
We present here high-resolution seismic sections of crustal and uppermost mantle structure along two dense linear arrays across the Lower Yangtze region in the eastern South China Block (SCB). Our seismic images reveal two low-velocity anomalies (LVAs) in the uppermost mantle which we interpreted as relic (still cooling) mantle magma chambers ponding and underplating beneath the base of the crust in the areas of the Dexing porphyry copper deposits and the Cretaceous South Anhui granites. The Moho and LAB discontinuities imaged also exhibit deformation directly above the two mantle LVAs, which probably indicate local mantle...
Source: Physics of the Earth and Planetary Interiors - October 22, 2019 Category: Physics Source Type: research

The melt content of the low velocity layer in the eastern South China: Implications for the subduction process of the Western Pacific plate
Publication date: Available online 21 October 2019Source: Physics of the Earth and Planetary InteriorsAuthor(s): Maining Ma, Xiaoya Zhou, Zhishuang Xu, Guohui Li, Yongbing Li, Yuanze ZhouAbstractThe low-velocity layer (LVL) atop the mantle transition zone involves diapiric segregating, melt upwelling, mantle mixing, magmatic eruption and the remnants. The lateral variations of the LVL could record the process of the subducting plates. The LVL beneath the eastern South China intensively affected by the subduction of Western Pacific plate since Mesozoic is imaged with observed P-wave triplications recorded by the dense Chine...
Source: Physics of the Earth and Planetary Interiors - October 22, 2019 Category: Physics Source Type: research

Gravimetric study of the shallow basaltic plumbing system of Tenerife, Canary Islands
Publication date: Available online 21 October 2019Source: Physics of the Earth and Planetary InteriorsAuthor(s): S. Sainz-Maza Aparicio, J. Martí, F.G. Montesinos, A. Borreguero Gómez, J. Pereda de Pablo, P. Vaquero Fernández, M. Calvo García-MarotoAbstractRecent studies on intraplate volcanic islands reveal that magma ascends sub-vertically through these volcanic edifices, following well-defined zones in the lithospheric mantle and oceanic crust, and occasionally suffering lateral propagation along rift zones when it reaches very shallow depths. Visualizing the internal structure of the shallow...
Source: Physics of the Earth and Planetary Interiors - October 22, 2019 Category: Physics Source Type: research

Effects of Coulomb stress change on Mw ≥ 6 earthquakes in the Caucasus
Publication date: Available online 21 October 2019Source: Physics of the Earth and Planetary InteriorsAuthor(s): Bahruz Ahadov, Shuanggen JinAbstractCoulomb stress variations may trigger earthquakes, while the incident of stress transfer mechanisms is not clear. In this paper, Coulomb stress changes are investigated related to the sequences of strong earthquakes in the Caucasus region, which followed the 1988 Mw6.8 in Spitak, the 1991 Mw6.9 in Racha and the 2000 Mw6.2 in Baku. Our results show that the mainshocks induced a variation in the stress field where most of the seismic events occurred. Coulomb stress increases 2...
Source: Physics of the Earth and Planetary Interiors - October 22, 2019 Category: Physics Source Type: research

Three-dimensional ground motion modelling in the Kachchh rift zone, Gujarat, India
Publication date: Available online 20 October 2019Source: Physics of the Earth and Planetary InteriorsAuthor(s): Prantik Mandal, Kimiyuki AsanoAbstractThe strong motion dataset of the 6 April 2006 Bhuj aftershock of Mw5.5 from 16 three-component accelerograph stations are used here to perform a detailed ground motion modelling in the Kachchh rift basin. First, we estimate the 1-D velocity structure model down to the bedrock at 16 accelerograph sites, through the Genetic Algorithm inversion of strong motion waveforms. Then, a 3-D velocity structure model of the basin is constructed using the modelled 1-D velocity structure ...
Source: Physics of the Earth and Planetary Interiors - October 21, 2019 Category: Physics Source Type: research

Refined 3600 years palaeointensity curve for Mexico
Publication date: Available online 19 October 2019Source: Physics of the Earth and Planetary InteriorsAuthor(s): Ahmed Nasser Mahgoub, Erick Juárez-Arriaga, Harald Böhnel, Linda R. Manzanilla, Ann CyphersAbstractOur knowledge of the Earth's magnetic field intensity changes over the past few thousand years is still limited because of the uneven spatial and temporal distribution of data, which also includes the Americas. The present study reports 41 new palaeointensity data covering the past 3600 years which, together with 38 previously published data of similar quality, are used to construct a palaeointensity ...
Source: Physics of the Earth and Planetary Interiors - October 20, 2019 Category: Physics Source Type: research

Evidence for an upwelling mantle plume beneath the Songliao Basin, Northeast China
Publication date: Available online 17 October 2019Source: Physics of the Earth and Planetary InteriorsAuthor(s): Chuansong HeAbstractA mushroom-like low-velocity body (MLLVB) was defined by tomography beneath Northeast China, which may be linked to a vestige of the Mesozoic upwelling mantle plume. However, multiple lines of evidence indicate that the necessary condition of the upwelling is that the upwelling mantle plume has a temperature sufficiently higher than that of the surrounding mantle. The upwelling mantle plume cannot be defined only based on the low-velocity structure. To investigate this issue, I conducted comm...
Source: Physics of the Earth and Planetary Interiors - October 19, 2019 Category: Physics Source Type: research

Editorial Board
Publication date: October 2019Source: Physics of the Earth and Planetary Interiors, Volume 295Author(s): (Source: Physics of the Earth and Planetary Interiors)
Source: Physics of the Earth and Planetary Interiors - October 16, 2019 Category: Physics Source Type: research

2D kernel-based imaging of coda-Q space variations in the Gargano Promontory (Southern Italy)
Publication date: Available online 12 September 2019Source: Physics of the Earth and Planetary InteriorsAuthor(s): Marilena Filippucci, Pezzo, Salvatore de Lorenzo, Andrea TallaricoAbstractCrustal seismic attenuation in the Gargano Promontory (Southern Italy) was inferred by analyzing coda waves of about one hundred small magnitude earthquakes recorded by the OTRIONS local seismic network. Coda attenuation Qc was computed using the Sato (1977) model, i.e. the assumption of single back-scattering, at different lapse times and at different frequencies. Average Qc is comparable with the same quantity measured in the adjacent ...
Source: Physics of the Earth and Planetary Interiors - September 13, 2019 Category: Physics Source Type: research

Assessment of heterogeneities of the shallow crust from geophysical logging in the Koyna-Warna region, Deccan Volcanic Province, India
Publication date: Available online 10 September 2019Source: Physics of the Earth and Planetary InteriorsAuthor(s): D. Gopinadh, N. Satyavani, Kusumita Arora, M. Srihari Rao, K.N.S.S.S. Srinivas, Y. Srinu, P. Sai Vijay Kumar, H.V.S. SatyanarayanaAbstractAnalysis and comparison of geophysical logs from seven exploratory boreholes of 1–1.5 km depth in the Koyna-Warna region of India illustrate variations in physical properties and structural characteristics of the basalts and underlying granite-gneiss basement in and around the seismogenic zone. In the north, south of the Koyna reservoir, densities are higher, gamma v...
Source: Physics of the Earth and Planetary Interiors - September 12, 2019 Category: Physics Source Type: research

GeoVReality: A computational interactive virtual reality visualization framework and workflow for geophysical research
We present a new interactive computational virtual reality (VR) visualization framework for geophysical big data and models for the development of immersive collaborative virtual reality applications with a focus on targeted processing and interaction of big data. The framework includes a high-performance scalable persistent storage solution for the spatial analysis of Geospatial Information System (GIS), which uses an engine based on efficient in-memory computing. To more effectively visualize and interact in a VR environment, a machine learning algorithm library is used for compressing and extracting visual data. The fra...
Source: Physics of the Earth and Planetary Interiors - September 12, 2019 Category: Physics Source Type: research

New normal mode constraints on bulk inner core velocities and density
Publication date: Available online 6 September 2019Source: Physics of the Earth and Planetary InteriorsAuthor(s): Alexander J.S. Robson, Barbara RomanowiczAbstractInner core elastic parameters Vp, Vs and density (ρ) inform both experimental and theoretical studies of inner core composition and potential light element candidates. Meanwhile, constraints on the density jump at the inner core boundary offer much-needed observational insight into the processes powering the geodynamo. Thus, obtaining accurate observational constraints on the elastic structure of the inner core is key to gaining better understanding of its co...
Source: Physics of the Earth and Planetary Interiors - September 7, 2019 Category: Physics Source Type: research

Mapping P-wave azimuthal anisotropy of the New Madrid seismic zone
Publication date: Available online 29 August 2019Source: Physics of the Earth and Planetary InteriorsAuthor(s): Zewei Wang, Dapeng ZhaoAbstractWe determine a detailed tomographic model of 3-D P-wave azimuthal anisotropy in the crust and upper mantle beneath the New Madrid seismic zone (NMSZ) using a large number of high-quality arrival-time data of 877 local earthquakes and relative travel-time data of 1511 teleseismic events recorded at 62 USArray stations. The tomographic inversion is conducted by using a limit-memory Broyden–Fletcher–Goldfarb–Shanno algorithm for bound constrained optimization. Because...
Source: Physics of the Earth and Planetary Interiors - August 31, 2019 Category: Physics Source Type: research

Toward a Boot Strap Hypothesis of Plate Tectonics: Feedbacks Between Plates, The Asthenosphere, and The Wavelength of Mantle Convection
Publication date: Available online 24 August 2019Source: Physics of the Earth and Planetary InteriorsAuthor(s): A. Lenardic, M. Weller, T. Höink, J. SealesAbstractThe solid Earth system is characterized by plate tectonics, a low viscosity zone beneath plates (the asthenosphere), and long wavelength flow in the convecting mantle. We use suites of numerical experiments to show: 1) How long wavelength flow and the operation of plate tectonics can generate and maintain an asthenosphere, and 2) How an asthenosphere can maintain long wavelength flow and plate tectonics. Plate subduction generates a sub-adiabatic temperature...
Source: Physics of the Earth and Planetary Interiors - August 25, 2019 Category: Physics Source Type: research

Phase relations of MgSiO3-FeSiO3 system up to 64 GPa and 2300 K using multianvil apparatus with sintered diamond anvils
Publication date: Available online 17 August 2019Source: Physics of the Earth and Planetary InteriorsAuthor(s): Takeshi Arimoto, Tetsuo Irifune, Masayuki Nishi, Yoshinori Tange, Takehiro Kunimoto, Zhaodong LiuAbstractWe have developed techniques to perform precise determinations of phase transition boundaries under the pressure and temperatures corresponding to those of the deep lower mantle, using Kawai-type multianvil apparatus (KMA) with sintered diamond anvils. By optimizing the materials and dimensions of the high-pressure furnace assembly, we achieved stable generation of high temperature to 2300 K, at pressures up...
Source: Physics of the Earth and Planetary Interiors - August 19, 2019 Category: Physics Source Type: research

Editorial Board
Publication date: September 2019Source: Physics of the Earth and Planetary Interiors, Volume 294Author(s): (Source: Physics of the Earth and Planetary Interiors)
Source: Physics of the Earth and Planetary Interiors - August 16, 2019 Category: Physics Source Type: research

Partition coefficient of phosphorus between liquid metal and silicate melt with implications for the Martian magma ocean
In this study, we investigated the behavior of phosphorus in a Martian magma ocean scenario, and measured the partition coefficient of phosphorus (DP) between liquid metal and silicate melt within the pressure range of 3–8 GPa, temperatures between 1973 and 2173 K and oxygen fugacity ranging from −1.5 to ~ −2.5 as normalized to the iron-wüstite oxygen buffer. Our results show DP increasing with pressure but decreasing with temperature. A decrease of oxygen fugacity has a negative effect on DP. The moderately siderophile character of phosphorus indicates that the Martian core might be an important...
Source: Physics of the Earth and Planetary Interiors - August 16, 2019 Category: Physics Source Type: research

Fate of water in subducted hydrous sediments deduced from stability fields of FeOOH and AlOOH up to 20 GPa
Publication date: Available online 27 July 2019Source: Physics of the Earth and Planetary InteriorsAuthor(s): Takashi Yoshino, Edward Baker, Kyle DuffeyAbstractFe- and Al-hydroxides (FeOOH and AlOOH) in sedimentary rocks form the top part of the subducted oceanic lithosphere and are known to be stable along a normal geotherm in the lower mantle. Banded Iron Formations (BIFs) and bauxite ore deposits formed in the Earth's oceans can transport significant amount of water into the Earth's deep interior by subduction of FeOOH and AlOOH and may occasionally serve water to the core. However, stabilities of these hydrous phases h...
Source: Physics of the Earth and Planetary Interiors - July 28, 2019 Category: Physics Source Type: research

Nebular Atmosphere to Magma Ocean: A Model for Volatile Capture During Earth Accretion
Publication date: Available online 26 July 2019Source: Physics of the Earth and Planetary InteriorsAuthor(s): Peter L. Olson, Zachary D. SharpAbstractThe origin and abundance of mantle volatiles present major questions for Earth’s evolution. Here we quantify volatile capture from an atmosphere derived from the solar nebula during accretion, using a boundary layer model of magma ocean dynamics coupled to a nebular atmosphere model adapted to Earth formation. Key elements include (i) nebular atmosphere winds based on scaling laws for deep rotating fluids; (ii) water production at the magma surface; and (iii) gas transf...
Source: Physics of the Earth and Planetary Interiors - July 26, 2019 Category: Physics Source Type: research

Mechanical coupling of the motion of the surface plate and the lower mantle slab: Effects of viscosity hill, yield strength, and depth-dependent thermal expansivity
Publication date: September 2019Source: Physics of the Earth and Planetary Interiors, Volume 294Author(s): Takeo Kaneko, Tomoeki Nakakuki, Hikaru IwamoriAbstractSinking rates of the subducted lithosphere in the Earth's lower mantle inferred from seismic tomography images indicate much lower rates than that of the observed subducting surface plate motion. This implies that the surface plate motion is independent of descending flow in the deep mantle. Seeking to understand the mechanical coupling of the slab penetrating into the deepest mantle with the surface plate motion, we performed numerical modeling of the subducting l...
Source: Physics of the Earth and Planetary Interiors - July 26, 2019 Category: Physics Source Type: research

Voxel solution and 3D sub-surface imaging in the Douala sedimentary sub-basin (Cameroon)
Publication date: Available online 22 July 2019Source: Physics of the Earth and Planetary InteriorsAuthor(s): Eric N. Ndikum, Kenfack J. Victor, F. Koumetio, Serge H. Pokam Kengni, Charles T. TabodAbstractGravity data consisting of a total of 128 data points located between latitudes 3° 21′N and 4° 9′ N and longitudes 8° 27′ E and 9° 16′ E have been computed for Bouguer and residual anomaly maps in this study. From the plots of these maps which are characterized by very high positive ring shaped contours towards the centre, which are suggestive of a subsurface intrusive body, three a...
Source: Physics of the Earth and Planetary Interiors - July 24, 2019 Category: Physics Source Type: research

Experimentally deformed lawsonite at high pressure and high temperature: Implication for low velocity layers in subduction zones
In this study, we report a new lawsonite CPO pattern resulting from dislocation creep deformation that has not been previously observed. The [100] axes concentrate into the shear direction and the [010] axes are normal to the shear plane, respectively (we refer to this as “type-1” CPO). Such CPO is consistent with our transmission electron microscope (TEM) observations identifying (010)[100] as a dominant dislocation slip-system. The seismic properties resulting from this CPO show the fast P-wave direction to be parallel to the shear direction, and the slow P-wave direction and maximum S-wave anisotropy normal ...
Source: Physics of the Earth and Planetary Interiors - July 19, 2019 Category: Physics Source Type: research

New interpretation of the reduction phenomenon in the electrical resistivity of rock masses before local earthquakes
This article attempts to quantify this hypothesis based on 3D modeling of the observed electromagnetic effects. It is shown that variations in the apparent resistivity are due to changes in the electrical resistivity in a narrow fault zone located at the focus of the dipole-dipole sounding system. The changes occur at depths of
Source: Physics of the Earth and Planetary Interiors - July 16, 2019 Category: Physics Source Type: research

Publisher's note
Publication date: August 2019Source: Physics of the Earth and Planetary Interiors, Volume 293Author(s): (Source: Physics of the Earth and Planetary Interiors)
Source: Physics of the Earth and Planetary Interiors - July 16, 2019 Category: Physics Source Type: research

Editorial Board
Publication date: August 2019Source: Physics of the Earth and Planetary Interiors, Volume 293Author(s): (Source: Physics of the Earth and Planetary Interiors)
Source: Physics of the Earth and Planetary Interiors - July 16, 2019 Category: Physics Source Type: research

3D non-smooth inversion of gravity data by zero order minimum entropy stabilizing functional
Publication date: Available online 3 July 2019Source: Physics of the Earth and Planetary InteriorsAuthor(s): Mohammad RezaieAbstractThe inversion of gravity data can generate subsurface density models by minimizing a Tikhonov parametric functional. The Tikhonov parametric functional has a misfit functional and a stabilizing functional which the latter functional governs the solution to be smooth or piecewise-constant. Piecewise-constant models can discern sharp geological interfaces. Therefore the models are highly demanded especially for mineral exploration. Some stabilizing functionals such as minimum support (MS) and mi...
Source: Physics of the Earth and Planetary Interiors - July 5, 2019 Category: Physics Source Type: research

Source characteristics of the NW Himalaya and its adjoining region: Geodynamical implications
In this study, we propose a novel interpretation of source parameters estimated using Brune model for the NW Himalaya and its adjoining region. Analysis of 157 events (2.2 ≤ Mw ≤ 4.9) resulted in the scaling relationship between seismic moment (M0) and corner frequency (fc) for the region as: M0 = 8 × 1022 fc−2.89, which is in good unison to the Garhwal and the Kumaon Himalaya with analogous seismogenic potential. Variability of Kappa (0.01 s - 0.08 s) with varying number of events (2.5 ≤ M ≤ 5.0) at different depths is indicative of nature and extent of structural hete...
Source: Physics of the Earth and Planetary Interiors - July 5, 2019 Category: Physics Source Type: research

A study of the relations between ML, Me, Mw, apparent stress, and fault aspect ratio
Publication date: Available online 4 July 2019Source: Physics of the Earth and Planetary InteriorsAuthor(s): Robert F. MereuAbstractThe energy magnitude Me used here is based on the square root of the observed seismic trace Lg coda energy. This version of the magnitude is of great interest as it can be used as a more accurate replacement for ML. To-day the moment magnitude Mw is the magnitude that is used particularly for large earthquakes and unlike ML, it does not saturate. In this paper, it is shown that the theoretical “ratio” between the moment magnitude Mw and Me and therefore Mw and ML for an individual ...
Source: Physics of the Earth and Planetary Interiors - July 5, 2019 Category: Physics Source Type: research

Structure of the crust and upper mantle beneath Bass Strait, southeast Australia, from teleseismic body wave tomography
We present new constraints on the lithospheric velocity structure of Bass Strait and the adjoining landmasses of mainland Australia and Tasmania in order to better constrain their geological and tectonic relationship. This is achieved by performing teleseismic tomography using data from fifteen deployments of WOMBAT and BASS transportable arrays, which span southeastern Australia. The starting model for the teleseismic tomography includes crustal velocity structure constrained by surface waves extracted from ambient seismic noise data and a Moho surface and broad-scale variations in 3-D upper mantle velocity structure from...
Source: Physics of the Earth and Planetary Interiors - July 3, 2019 Category: Physics Source Type: research

Effect of calcium on the elasticity of majoritic garnets and the seismic gradients in the mantle transition zone
Publication date: Available online 21 June 2019Source: Physics of the Earth and Planetary InteriorsAuthor(s): Carmen Sanchez-Valle, Jingyun Wang, Arno RorhbachAbstractBrillouin scattering spectroscopy was applied to investigate the effect of calcium on the single-crystal elasticity of majorite garnet, Mj42Py50.5Gr7.5, up to 25 GPa, spanning the conditions of the mantle transition zone. The adiabatic bulk and shear moduli, and their pressure derivatives are Ks = 159(2) GPa, μ = 87(1) GPa, KS′ = 4.3(2) and μ′ = 1.2(1). Calcium substitution has a small but resolvable effect on the elasticit...
Source: Physics of the Earth and Planetary Interiors - June 23, 2019 Category: Physics Source Type: research

Upper mantle temperature structure of the North China Craton
Publication date: Available online 22 June 2019Source: Physics of the Earth and Planetary InteriorsAuthor(s): Dong Yan, You Tian, Dapeng Zhao, Cai Liu, Hongxiang Zhu, Honghao LiAbstractWe investigate three-dimensional (3-D) temperature distribution of the upper mantle at depths of 50–200 km beneath the North China Craton (NCC) and surrounding areas using high-resolution P- and S-wave velocity models as well as mineral physics and geothermal data and methods. The thickness of thermal lithosphere is also estimated assuming its bottom has a mantle adiabatic temperature of 1300 °C. Our results show that the study...
Source: Physics of the Earth and Planetary Interiors - June 23, 2019 Category: Physics Source Type: research

Mechanical coupling of motions between the surface plate and the lower mantle slab: Effects of viscosity hill, yield strength, and depth-dependent thermal expansivity
Publication date: Available online 22 June 2019Source: Physics of the Earth and Planetary InteriorsAuthor(s): Takeo Kaneko, Tomoeki Nakakuki, Hikaru IwamoriAbstractSinking rates of the subducted lithosphere in the Earth's lower mantle inferred from seismic tomography images indicate much lower rates than that of the observed subducting surface plate motion. This implies that the surface plate motion is independent of descending flow in the deep mantle. Seeking to understand the mechanical coupling of the slab penetrating into the deepest mantle with the surface plate motion, we performed numerical modeling of the subductin...
Source: Physics of the Earth and Planetary Interiors - June 23, 2019 Category: Physics Source Type: research

Lithosphere and shallow asthenosphere rheology from observations of post-earthquake relaxation
Publication date: Available online 19 June 2019Source: Physics of the Earth and Planetary InteriorsAuthor(s): Fred F. PollitzAbstractIn tectonically active regions, post-earthquake motions are generally shaped by a combination of continued fault slippage (afterslip) on a timescale of days to months and viscoelastic relaxation of the lower crust and upper mantle on a timescale of days to years. Transient crustal motions have been observed following numerous magnitude>~7 earthquakes in various tectonic settings: continental rift zones (Basin and Range), continental plate boundary zones (San Andreas fault corridor; Alaska;...
Source: Physics of the Earth and Planetary Interiors - June 20, 2019 Category: Physics Source Type: research

Effect of water on the dislocation mobility in garnet: Evidence from the Shuanghe UHP eclogites, Dabie orogen, China
Publication date: Available online 4 June 2019Source: Physics of the Earth and Planetary InteriorsAuthor(s): Zhanjun Xie, Xiangwen Liu, Zhenmin JinAbstractTo better understand the effect of water on the plasticity of garnet, the water content and dislocation structures in 10 deformed garnet grains from 8 ultrahigh pressure (UHP) eclogite samples collected at Shuanghe, Dabie orogen, China, were investigated by Fourier transform infrared (FTIR) spectroscopy and transmission electron microscopy (TEM). The FTIR results show that the mean water content in these garnet grains range from 66 to 2256 wt. ppm H2O. The TEM observatio...
Source: Physics of the Earth and Planetary Interiors - June 5, 2019 Category: Physics Source Type: research