A structural model for the Java Margin Subduction Zone, Indonesia, from multi-channel and wide-angle seismic data

The plate margin offshore Java and the Lesser Sunda islands are located in the eastern portion of the Sunda plate margin, which starts from Burma in the northwest to the Banda arc in the southeast. Different geological configurations in the Sunda plate margin vary enormously from the west to the east due to the variations in sediment supply and the different nature of the oceanic plates along the convergent plate boundary. The Sunda arc hosts earthquakes spanning from moderate magnitude ones to some of the largest earthquakes on Earth. In order to understand the current tectonic structure, the oceanic crust relief, and the temporal evolution of the large volume accretionary mass of the eastern Java and Lesser Sunda margins, we use MCS streamer data and OBS data collected by BGR and GEOMAR to image the plate interface reflection, the upper plate tectonic structure, and velocity attributes of the convergent plates. In this study, we incorporate an innovative seismic processing approach called the Non-Rigid Matching technique applied to the reflection tomography and the pre-stack depth migration and retrieve the structural image of the forearc wedge and the geometry of the plate interface. The depth migrated seismic sections and the bathymetry reveal different scales and shapes of the oceanic relief. By comparing the observed subducting seamount location with the 1994 tsunami earthquake epicentre, the co-seismic slip model, and the aftershock focal mechanisms, we conclude that the seamount acts as an earthquake barrier in the 1994 rupture's propagation process and is weakly coupled in the inter-seismic period before the co-seismic rupture

A structural model for the Java Margin Subduction Zone, Indonesia, from multi-channel and wide-angle seismic data

The plate margin offshore Java and the Lesser Sunda islands are located in the eastern portion of the Sunda plate margin, which starts from Burma in the northwest to the Banda arc in the southeast. Different geological configurations in the Sunda plate margin vary enormously from the west to the east due to the variations in sediment supply and the different nature of the oceanic plates along the convergent plate boundary. The Sunda arc hosts earthquakes spanning from moderate magnitude ones to some of the largest earthquakes on Earth. In order to understand the current tectonic structure, the oceanic crust relief, and the temporal evolution of the large volume accretionary mass of the eastern Java and Lesser Sunda margins, we use MCS streamer data and OBS data collected by BGR and GEOMAR to image the plate interface reflection, the upper plate tectonic structure, and velocity attributes of the convergent plates. In this study, we incorporate an innovative seismic processing approach called the Non-Rigid Matching technique applied to the reflection tomography and the pre-stack depth migration and retrieve the structural image of the forearc wedge and the geometry of the plate interface. The depth migrated seismic sections and the bathymetry reveal different scales and shapes of the oceanic relief. By comparing the observed subducting seamount location with the 1994 tsunami earthquake epicentre, the co-seismic slip model, and the aftershock focal mechanisms, we conclude that the seamount acts as an earthquake barrier in the 1994 rupture's propagation process and is weakly coupled in the inter-seismic period before the co-seismic rupture

Reflection tomography by depth warping: A case study across the Java trench

Accurate subsurface velocity models are crucial for geological interpretations based on seismic depth images. Seismic reflection tomography is an effective iterative method to update and refine a preliminary velocity model for depth imaging. Based on residual move-out analysis of reflectors in common image point gathers an update of the velocity is estimated by a ray-based tomography. To stabilize the tomography, several preconditioning strategies exist. Most critical is the estimation of the depth error to account for the residual move-out of the reflector in the common image point gathers. Because the depth errors for many closely spaced image gathers must be picked, manual picking is extremely time-consuming, human biased, and not reproducible. Data-driven picking algorithms based on coherence or semblance analysis are widely used for hyperbolic or linear events. However, for complex-shaped depth events, pure data-driven picking is difficult. To overcome this, the warping method named Non-Rigid Matching is used to estimate a depth error displacement field. Warping is used, e.g., to merge photographic images or to match two seismic images from time-lapse data. By calculating the displacements between an offset to its neighbouring offset in the common image point domain, a locally smooth-shaped displacement field is defined for each data sample. Depending on the complexity of the subsurface, sample tracking through the displacement field along predefined horizons or on a simple regular grid yields discrete depth error values for the tomography. The application to a multi-channel seismic line across the Sunda subduction zone offshore Lombok island, Indonesia, illustrates the approach and documents the advantages of the method to estimate a detailed velocity structure in a complex tectonic regime. By incorporating the warping scheme into the reflection tomography, we demonstrate an increase in the velocity resolution and precision by improving the data-driven accuracy of depth error picks with arbitrary shapes. This approach offers the possibility to use the full capacities of tomography and further leads to more accurate interpretations of complex geological structures

Extremely thinned continental crust underneath the Ligurian Basin?

The Ligurian Basin is situated at the transition from the western Alpine orogeny to the Apennine system, an area where a change in subduction polarity is observed. The back-arc basin was generated by the southeast trench retreat of the Apennines-Calabrian subduction zone. The opening took place from late Oligocene to Miocene. While the extension led to continental thinning and subsidence, oceanic spreading with unroofing of mantle material was proposed for the late opening period, 21-16 Ma. To shed light on the present day crustal and lithospheric architecture of the Ligurian Basin, active and passive seismic data have been recorded on ocean bottom seismometers of a long-term network consisting of 29 broad-band stations, installed from June 2017 to February 2018 in the framework of SPP2017 4D-MB, the German component of AlpArray. Two refraction seismic profiles were shot to serve two aspects: (1) Determine the orientation of the horizontal components of the long-term instruments and (2) estimate the velocity distribution of the upper lithosphere, to provide a velocity model for the passive seismic data analysis. Good quality data have been recorded, regional and teleseismic events as well as active shots could be detected by the network stations. The majority of the refraction seismic data show mantle phases at offsets up to 70 km and a very prominent wide-angle reflection originating at the crust mantle boundary. Its features share a number of characteristics (i.e. offset range, continuity) generally associated with continental settings rather than mimicking seafloor spreading lithosphere emplaced in back-arc basins. Based on traveltime tomography along the refraction lines, the crust-mantle boundary is determined at ~9.5 km depth below seafloor. The acoustic basement is difficult to map seismically. The transition to the crystalline basement is indicated at a depth of ~6.5 km below seafloor. The absolute seismic velocities can be interpreted as hyper-extended continental crust or serpentinised mantle. The thick sedimentary coverage allows for long lasting extension of the crust. The crustal portion interpreted from the seismic velocities thickens towards the north which is in good agreement with the anti-clockwise rotation of the Corsica-Sardinia block and an associated gradual opening of the Ligurian Basin

Effects of land use types on soil erodibility in a small karst watershed in western Hubei

Background Soil erosion is a severe problem in the karst watershed, and analysis of soil erosion at the watershed scale is urgently needed. Methods This study tried to estimate the soil erodibility factor (K-factor) using the Erosion Productivity Impact Calculator (EPIC) nomograph and evaluate the spatial distribution of the predicted K-factor in a karst watershed. Soil properties and K-factors of five land use types (NF: natural mixed forest, CF: cypress forest, EF: economic forest, ST: stone dike terrace, VF: vegetable land) in the Xialaoxi small watershed were compared and key factors affecting erodibility were analyzed. Results Results showed that (1) The erodibility K-factor was unevenly distributed within different site types and strongly influenced by anthropogenic activities. The soil K-factors of sample sites subjected to frequent human disturbance (ST, VF) were high, ranging from 0.0480-0.0520 t hm2 h/(MJ mm hm2), while the soil K-factors of natural site types (NF, CF, and EF) were low, ranging from 0.0436-0.0448 t hm2 h/(MJ mm hm2). (2) The soil texture in the Xialaoxi watershed was mostly loamy, and that of the agricultural areas frequently disturbed by agricultural practices (ST, VF) was silty loam. (3) Soil carbon fractions were affected by land use types. Soil organic carbon storage of NF and CF had strong spatial heterogeneity. The soil organic carbon (SOC) and labile organic carbon (LOC) of the two were significantly higher than those of the disturbed EF and cultivated land soil. (4) There was a synergistic effect between the soil properties and the K-factor. K was significantly negatively related to sand fractions (2-0.05 mm) and non-capillary porosity, while positively related to silt content (0.05–0.002 mm). Overall, changes in bulk density (BD), total porosity (TP), non-capillary porosity (NCP), texture, and organic matter content caused by natural restoration or anthropogenic disturbance were the main reasons for soil erodibility. Natural care (sealing) and construction of stone dike planting practices were effective ways to reduce soil erosion in small karst watershed areas of western Hubei

Lithium Bis(fluorosulfony)imide-Lithium Hexafluorophosphate Binary-Salt Electrolytes for Lithium-Ion Batteries: Aluminum Corrosion Behaviors and Electrochemical Properties

© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Aluminum corrosion behaviors and electrochemical properties of Lithium bis(fluorosulfony)imide (LiFSI)-lithium hexafluorophosphate (LiPF6) binary-salt electrolytes containing mixtures of LiFSI and LiPF6 (with a total salt content of 1.2 mol L−1) with different molar ratios in EC/EMC (3:7, by vol.) solutions are systematically investigated. Our experimental results from cyclic voltammetry, scanning electron microscopy (SEM), chronoamperometry and the charge-discharge measurements of Li/LiNi1/3Co1/3Mn1/3O2 half-cells demonstrate that the LiFSI-LiPF6 binary-salt electrolytes with the LiFSI concentrations lower than 0.3 mol L−1 exhibit not only passivating aluminum current collectors at 4.3 V vs. Li+/Li, but also improved cycling performance. Meanwhile, Artificial Graphite/LiNi1/3Co1/3Mn1/3O2 (AG/NMC111) pouch cells made with the LiFSI(0.2)-LiPF6 (1.0) electrolyte with the LiFSI concentration of 0.2 mol L−1 display an excellent cycling stability with 93.9% capacity retention at 1 C rate after 360 cycles, and enhanced capacity retention at −20 °C, 60 °C and after 55 °C storage for 30 days compared to cells with 1.2 mol L−1 LiPF6/EC-EMC conventional electrolyte. This work confirms that binary-salt electrolytes system, such as LiFSI-LiPF6, may be a promising method to enhance the longevity and storage properties of Li-ion batteries

Oxidation decomposition mechanism of fluoroethylene carbonate-based electrolytes for high-voltage lithium ion batteries: a DFT calculation and experimental study

The oxidative decomposition mechanism of fluoroethylene carbonate (FEC) used in high-voltage batteries is investigated by using density functional theory (DFT). Radical cation FEC•+ is formed from FEC by transferring one electron to electrode and the most likely decomposition products are CO2 and 2-fluoroacetaldehyde radical cation. Other possible products are CO, formaldehyde and formyl fluoride radical cations. These radical cations are surrounded by much FEC solvent and their radical center may attack the carbonyl carbon of FEC to form aldehyde and oligomers of alkyl carbonates, which is similar with the oxidative decomposition of EC. Then, our experimental result reveals that FEC-based electrolyte has rather high anodic stability. It can form a robust SEI film on the positive electrode surface, which can inhibit unwanted electrolyte solvent and LiPF6 salts decomposition, alleviate Mn/Ni dissolution and therefore, improve the coulombic efficiency and the cycling stability of high voltage LiNi0.5Mn1.5O4 positive electrodes. This work displays that FEC-based electrolyte systems have considerable potential replacement of the EC-based electrolyte for the applications in 5 V Li-ion batteries

A Subducting Seamount Imaged in the Rupture Zone of the 1994 Java Earthquake, and Its Implication on Co-seismic Slip Propagation and Tsunami Generation

The 2 June 1994 Java (Indonesia) tsunami earthquake ruptured in a seismically quiet subduction zone and generated a larger-than-expected tsunami. Since the peak of the co-seismic slip occurred underneath a local bathymetric high, the 1994 event was previously interpreted as being caused by a subducting seamount. Combining a re-processed seismic reflection line across the rupture area with a refraction tomography P-wave velocity model, multibeam bathymetry, and gravity data suggests that rupture over a subducted seamount is unlikely to explain the seismo-tectonic genesis of the event. The forearc high is rather related to the enhanced back-thrusting activity and an island arc crust backstop in the upper plate. We newly resolve a shallow subducting seamount seaward of the forearc high and up-dip of the rupture area. We propose that this seamount acted as a seismic barrier and may have diverted the co-seismic rupture into the overlying splay faults, which may have contributed to the larger-than-expected tsunam

Embryonic 6:2 FTOH exposure causes reproductive toxicity by disrupting the formation of the blood-testis barrier in offspring mice

Previous studies have revealed nephrotoxicity, hepatotoxicity, subchronic developmental and reproductive toxicity in rats exposed to fluorotelomer alcohol (FTOH). However, the effects of embryonic 6:2 FTOH exposure on the reproductive system of offspring mice remain unclear. The purpose of this study is to explore the reproductive toxic effects of embryonic 6:2 FTOH exposure on offspring male mice and the related molecular mechanisms. Therefore, the pregnant mice were given corn oil or 6:2 FTOH by gavage from gestational days 12.5–21.5. The results demonstrated that embryonic 6:2 FTOH exposure resulted in disrupted testicular structure, low expression of tight junction protein between Sertoli cells (SCs), impaired blood-testis barrier (BTB) formation and maturation, reduced sperm viability and increased malformation, and induced testicular inflammation in the offspring of mice. Further in vitro studies showed that 6:2 FTOH treatment upregulated MMP-8 expression by activating AKT/NF-κB signaling pathway, which in turn enhanced occludin cleavage leading to the disruption of SCs barrier integrity. In summary, this study demonstrated that 6:2 FTOH exposure caused reproductive dysfunction in male offspring through disruption of BTB, which provided new insights into the effects of 6:2 FTOH exposure on the offspring