ALBERT

Description: Effects of vegetation restoration on the aggregate stability and distribution of aggregate-associated organic carbon in a typical karst gorge region Solid Earth Discussions, 7, 2213-2242, 2015 Author(s): F. K. Tang, M. Cui, Q. Lu, Y. G. Liu, H. Y. Guo, and J. X. Zhou Changes in soil utilization significantly affect aggregate stability and aggregate-associated soil organic carbon (SOC). A field investigation and indoor analysis were conducted in order to study the soil aggregate stability and organic carbon distribution in the water-stable aggregates (WSA) of the bare land (BL), grassland (GL), shrubland (SL), and woodland (WL) in a typical karst gorge region. The results indicated that the BL, GL, SL, and WL were dominated by particles with sizes 〉 5 mm under dry sieving treatment, and that the soil aggregate contents of various sizes decreased as the particle size decreased. In addition, the BL, GL, SL, and WL were predominantly comprised of WSA 〈 0.25 mm under wet sieving treatment, and that the WSA contents initially increased, then decreased, and then increased again as the particle size decreased. Furthermore, at a soil depth of 0–60 cm, the mean weight diameter (MWD), geometrical mean diameter (GMD), and fractal dimensions ( D ) of the dry aggregates and water-stable aggregates in the different types of land were ranked, in descending order, as WL 〉 GL 〉 SL 〉 BL. The contents of WSA 〉 0.25 mm, MWD and GMD increased significantly, in that order, and the percentage of aggregate destruction (PAD) and fractal dimensions decreased significantly as the soil aggregate stability improved. The results of this study indicated that, as the SOC contents increased after vegetation restoration, the average SOC content of WL was 2.35, 1.37, and 1.26 times greater than that in the BL, GL, and SL, respectively. The total SOC and SOC associated in WSA of various sizes were the highest at a soil depth of 0–20 cm. In addition, the SOC contents of the WSA increased as the soil aggregate sizes decreased. The SOC contents of the WSA 〈 0.25 mm were highest except in the bare land, and the SOC contents of the aggregates 〈 0.25 mm, which ranged from 18.85 to 41.08 %, comprised the majority of the total aggregate SOC contents. The woodland and grassland facilitated WSA stability and SOC protection, thus, promoting the natural restoration of vegetation by reducing artificial disturbances could effectively restore the ecology of and prevent soil erosion in karst regions.

Description: Improvements in aggregate stability of recently deposited sediments supplemented with tea waste and farmyard manure Solid Earth Discussions, 7, 2037-2053, 2015 Author(s): B. Turgut and B. Köse Organic matter supplement is well-known to influence soil aggregate stability (AS), but the corresponding change in recently deposited fine sediment is not documented well. In this study, improvements in aggregate stability of recently deposited sediment supplemented with the farmyard manure (FYM) and tea waste (TW) during 18-week incubation under controlled conditions. The FYM and TW were applied to recently deposited sediment at different doses (0, 2.5, 5, 7.5, 10, 12.5, and 15 % on weight base). The AS was determined at different times after adding organic matter (2nd, 4th, 6th, 8th, 10th, 14th, and 18th weeks) using wet sieving methods. The results showed that aggregate stability of deposited sediment treated with TW was statistically significantly higher than these of samples treated with FYM. Aggregate stability increased with increasing doses of both FYM and TW. In the FYM applied samples, AS reached the highest value at the end of second week, and declined within the following incubation period. However, in the samples treated with TW, AS reached the highest value at the end of eighth week. The results of this study were clearly indicated that tea waste and farmyard manure applications noticeably increased aggregate stability of recently deposited sediment, therefore it is suggested that TW and FYM could be used for structural stabilization of sediments.

Description: Dynamic evaluation of ecosystem service value of the riparian zone based on remote sensing from 1986 to 2012 Solid Earth Discussions, 7, 2151-2184, 2015 Author(s): B. L. Fu, Y. Li, B. Zhang, B. S. Yin, H. L. Zhu, and Z. F. Xing In this paper, we calculated comparable and dynamic ecosystem service value per unit area in the riparian zone of Second Songhua River; then we also estimated changes in the value of ecosystem services resulting from land use changes; finally, we continuously evaluated the riparian ecosystem service value based on 520 basic evaluation units (BEUs) and explored the trend of the riparian ecosystem service value from 1986 to 2012. The results indicated that comparable economic values of per unit area food production of farmland ecosystems in 2012 almost increased three times more than that in 1986 from 154.83 to 382.45 $ ha −1 ; the people's willingness to pay for farmland ecosystem services increased from 0.24 in 1986 to 0.48 in 2012; the land areas supporting the environment and society generally declined, whereas areas of farmland significantly increased from 1986 to 2012; the riparian total ecosystem service value increased from 42.30 million $ in 1986 to 119.67 million $ in 2012, with an average increase rate of 4.06 % yr −1 ; the ecosystem service value of four reaches all have seen a sharp increase from 1986 to 2012; the average ecosystem service value of a reach was the smallest one in the four reaches, and the value of c and d reach was significantly more than other two reaches.

Description: Identification of vulnerable areas to soil erosion risk in India using GIS methods Solid Earth Discussions, 7, 1611-1637, 2015 Author(s): H. Biswas, A. Raizada, D. Mandal, S. Kumar, S. Srinivas, and P. K. Mishra This paper attempts to provide information for policy makers and soil conservation planners in the form of district-wise soil erosion risk (SER) maps prepared for the state of Telengana, India. The SER values for each district were computed by extracting the information on grid-wise soil erosion and soil loss tolerance limit values existing on the country-scale in a GIS environment. The objectives of the study were to (i) identify the areas of the state with high erosion risk, and (ii) identify areas with urgent needs of conservation measures. The results reveal that around 69% of the state has negligible risk of soil erosion above the tolerance limits, and does not call for immediate soil conservation measures. The remaining area (2.17M ha) requires conservation planning. Four districts, viz. Adilabad, Warangal, Khammam and Karimnagar are the most risk prone with more than one-fourth of their total geographical areas showing net positive SER values. In order to obtain a clearer picture and categorize the districts based on their extent of vulnerability, the Weighted Erosion Risk values were computed. Adilabad, Warangal and Khammam were identified as the worst-affected districts in terms of soil erosion and therefore need immediate attention for natural resource conservation.

Description: Cyclic fracturing during spine extrusion at Unzen volcano, Japan Solid Earth Discussions, 7, 2109-2149, 2015 Author(s): O. D. Lamb, S. De Angelis, K. Umakoshi, A. J. Hornby, J. E. Kendrick, and Y. Lavallée Rhythmic seismicity associated with spine extrusion is a well-documented phenomenon at a number of dome-forming volcanic systems. At Unzen volcano, Japan, a four year dome-forming eruption concluded with the emplacement of a spine from October 1994 to February 1995, offering a valuable opportunity to further investigate seismogenic processes at dome-forming volcanoes. Using continuous data recorded at a seismic station located close to the dome, this study explores trends in the seismic activity during the extrusion of the spine. We identify a total of 12 208 seismic events in the period between October 1994 and February 1995. Hourly event counts indicate cyclic activity with periods of ~ 40 to ~ 100 h, attributed to pulsatory ascent defined by strain localisation and faulting at the conduit margins. Waveform correlation revealed two strong clusters (a.k.a. multiplets, families) attributed to fracturing along the margins of the shallow, ascending plug. Further analysis indicates variable seismic velocities during spine extrusion, as well as migration of the cluster sources along the spine margins. Our interpretation of the results from seismic data analyses is supported by field and experimental observations, suggesting that the spine was extruded along an inclined conduit with brittle and ductile failure occurring along the margins. We infer that changes in stress conditions acting on the upper and lower spine margins led to deepening and shallowing of the faulting source, respectively. We demonstrate that the combination of geophysical, field and experimental evidence can help improve physical models of shallow conduit processes.

Description: Grazing effects on soil characteristics and vegetation of grassland in northern China Solid Earth Discussions, 7, 2283-2309, 2015 Author(s): Z. Wang, D. A. Johnson, and Y. Rong Large areas of grassland in the agro-pastoral region of northern China were converted into cropland for grain production, and the remaining grasslands are being overgrazed and seriously degraded. The objective of this study was to evaluate how reductions in grazing intensity affect the soil and vegetation characteristics in grasslands of northern China. Soil heterogeneity and vegetation characteristics were evaluated for ungrazed (UG), moderate grazing (MG), and heavy grazing (HG) sites. Grazing increased diversity, but heavy grazing decreased aboveground biomass and increased the non-grass component. Vegetation biomass was greatest at the UG site (220 g m −2 ) followed by the MG (99 g m −2 ) and HG (27 g m −2 ) sites ( P 〈 0.05). The non-grass proportion of total biomass increased with grazing intensity, which was 8, 16, and 48 % for UG, MG, and HG sites, respectively. Species richness at the MG and HG sites was significantly higher than at the UG site ( P 〈 0.05) with 3.6, 5.5, and 5.7 for UG, MG, and HG sites, respectively. Over grazing homogenized soil characteristics at a 10 m scale. The ranges of spatial autocorrelation for soil organic C (SOC) and total N were both 〉 120 m at the HG site, which was considerably larger than that at the MG and UG sites with corresponding distances of 17.3 and 20.8 m for the MG site and 25.8 and 15.0 m for the UG site, respectively. Therefore, MG was recommended as the preferred management alternative for grasslands in northern China because of increased plant diversity without negative consequences related to decreased forage quality and forage quantity, and soil heterogeneity in northern China's grasslands.

Description: Qualitative and quantitative changes in detrital reservoir rocks caused by CO 2 -brine-rock interactions during first injection phases (Utrillas sandstones, Northern Spain) Solid Earth Discussions, 7, 2243-2282, 2015 Author(s): E. Berrezueta, B. Ordóñez-Casado, and L. Quintana The aim of this article is to describe and interpret qualitative and quantitative changes at rock matrix scale of Lower-Upper Cretaceous sandstones exposed to supercritical (SC) CO 2 and brine. The effects of experimental injection of SC CO 2 during the first injection phases were studied at rock matrix scale, in a potential deep sedimentary reservoir in Northern Spain (Utrillas unit, at the base of the Cenozoic Duero Basin). Experimental wet CO 2 injection was performed in a reactor chamber under realistic conditions of deep saline formations ( P ≈ 78 bar, T ≈ 38 °C and 24 h exposure time). After the experiment, exposed and non-exposed equivalent sample sets were compared with the aim of assessing possible changes due to the effect of the CO 2 -brine exposure. Optical microscopy (OpM) and scanning electron microscopy (SEM) aided by optical image analysis (OIA) were used to compare the rock samples and get qualitative and quantitative information about mineralogy, texture and porous network distribution. Chemical analyses were performed to refine the mineralogical information and to obtain whole rock geochemical data. Brine composition was also analysed before and after the experiment. The results indicate an evolution of the pore network (porosity increase ≈ 2 %). Intergranular quartz matrix detachment and partial removal from the rock sample (due to CO 2 input/release dragging) are the main processes that may explain the porosity increase. Primary mineralogy (≈ 95 % quartz) and rock texture (heterogeneous sand with interconnected framework of micro-channels) are important factors that seem to enhance textural/mineralogical changes in this heterogeneous system. The whole rock and brine chemical analyses after interaction with SC CO 2 -brine do not present important changes in the mineralogical, porosity and chemical configuration of the rock with respect to initial conditions, ruling out relevant precipitation or dissolution at these early stages. These results, simulating the CO 2 injection near the injection well during the first phases (24 h) indicate that, in this environment where CO 2 displaces the brine, the mixture principally generates local mineralogical/textural re-adjustments due to physical detachment of quartz grains. Consequences deriving from these changes are variable. Possible porosity and permeability increases could facilitate further CO 2 injection but textural re-adjustment could also affect the rock physically. However, it is not clear yet what effect the quartz (solid suspension) could provoke in more distant areas of the rock. Quartz could be transported in the fluid flow path and probably accumulated at pore throats.

Description: POLENET/LAPNET teleseismic P-wave traveltime tomography model of the upper mantle beneath northern Fennoscandia Solid Earth Discussions, 7, 2527-2562, 2015 Author(s): H. Silvennoinen, E. Kozlovskaya, and E. Kissling The POLENET/LAPNET broadband seismic array was deployed in northern Fennoscandia (Finland, Sweden, Norway, and Russia) during the third International Polar Year 2007–2009. The array consisted of roughly 60 seismic stations. In our study we estimate the 3-D architecture of the upper mantle beneath the northern Fennoscandian shield using high-resolution teleseismic P-wave tomography. For this purpose 111 clearly recorded teleseismic events were selected and the data from the stations handpicked and analysed. Our study reveals a highly heterogeneous lithospheric mantle beneath the northern Fennoscandian shield though without any large high P-wave velocity area that may indicate presence of thick depleted lithospheric "keel". The most significant feature seen in the velocity model is a large elongated negative velocity anomaly (up to −3.5 %) in depth range 100–150 km in the central part of our study area that can be followed down to a depth of 200 km in some local areas. This low-velocity area separates three high-velocity regions corresponding to the cratons and it extends to greater depth below the Karelian craton.

Description: Strain localization in ultramylonitic marbles by simultaneous activation of dislocation motion and grain boundary sliding (Syros, Greece) Solid Earth Discussions, 7, 2663-2695, 2015 Author(s): A. Rogowitz, J. C. White, and B. Grasemann Extreme strain localization occurred in the center of the cross-cutting element of a flanking structure in almost pure calcite marbles from Syros, Greece. At the maximum displacement of 120 cm along the cross-cutting element evidence of grain size sensitive deformation mechanisms can be found in the ultramylonitic marbles, which are characterized by (1) an extremely small grain size (∼3 μm), (2) grain boundary triple junctions with nearly 120° angles, (3) a weak crystallographic preferred orientation with very low texture index ( J =1.4), (4) a random misorientation angle distribution curve and (5) the presence of small cavities. Using transmission electron microscopy a deformation sequence is observed comprising, first recrystallization by bulging resulting in the development of the fine-grained ultramylonite followed by the evolution of a high dislocation density (∼10 13 m −2 ) with ongoing deformation of the fine-grained ultramylonite. The arrangement of dislocations in the extremely fine grain sized calcite differs from microstructures created by classical dislocation creep mediated by combined glide and thermally activated climb. Instead, it exhibits extensive glide and dislocation networks characteristic of recovery accommodated by cross-slip and network-assisted dislocation movement without formation of idealized subgrain walls. The enabling of grain boundary sliding to dislocation activity is deemed central to initiating and sustaining strain softening and is argued to be an important strain localization process in calcite rocks, even at high strain rate (10 −9 s −1 ) and low temperature (300 °C).

Description: Seismo-electrics, electro-seismics, and seismo-magnetics for earth sciences Solid Earth Discussions, 7, 2563-2662, 2015 Author(s): L. Jouniaux and F. Zyserman The seismo-electromagnetic method (SEM) is used for non-invasive subsurface exploration. It shows interesting results for detecting fluids such as water, ice, oil, gas, CO 2 , and also to better characterise the subsurface in terms of porosity, permeability, and fractures. However, a limitation of this method is the low level of the induced signals. We first describe SEM's theoretical background, and the role of some key parameters. We then detail recent studies on SEM, through theoretical and numerical developments, and through field and laboratory observations, to show that this method can bring advantages compared to classical geophysical methods.

Description: Tectonothermal evolution in the core of an arcuate fold and thrust belt: the south-eastern sector of the Cantabrian Zone (Variscan belt, north-western Spain) María Luz Valín, Susana García-López, Covadonga Brime, Fernando Bastida, and Jesús Aller Solid Earth, 7, 1003-1022, doi:10.5194/se-7-1003-2016, 2016 The tectonothermal evolution of an area located in the core of the Ibero-Armorican Arc (Variscan belt) has been determined by using the conodont colour alteration index (CAI), Kübler index of illite (KI), the Árkai index of chlorite (AI) and the analysis of clay minerals and rock cleavage. The area is part of the Cantabrian Zone (CZ), which represents the foreland fold and thrust belt of the orogen. It has been thrust by several large units of the CZ, what resulted in the generation of a large number of synorogenic Carboniferous sediments. CAI, KI and AI values show an irregular distribution of metamorphic grade, independent of stratigraphic position. Two tectonothermal events have been distinguished in the area. The first one, poorly defined, is mainly located in the northern part. It gave rise to very-low-grade metamorphism in some areas and it was associated with a deformation event that resulted in the emplacement of the last large thrust unit and development of upright folds and associated cleavage ( S 1 ). The second tectonothermal event gave rise to low-grade metamorphism and cleavage ( S 2 ) crosscutting earlier upright folds in the central, western and southern parts of the study area. The event continued with the intrusion of small igneous rock bodies, which gave rise to contact metamorphism and hydrothermal alteration. This event was linked to an extensional episode due to a gravitational instability at the end of the Variscan deformation. This tectonothermal evolution occurred during the Gzhelian–Sakmarian. Subsequently, several hydrothermal episodes took place and local crenulation cleavage developed during the Alpine deformation.

Description: Microstructures and deformation mechanisms in Opalinus Clay: insights from scaly clay from the Main Fault in the Mont Terri Rock Laboratory (CH) Ben Laurich, Janos L. Urai, and Christophe Nussbaum Solid Earth Discuss., doi:10.5194/se-2016-94,2016 Manuscript under review for SE (discussion: open, 0 comments) Scaly clay is a well-known rock fabric that can develop in tectonic systems and that can alter the physical rock properties of a formation. However, internal microstructure and evolution of this fabric remains poorly understood. We examined the scaly microstructure of progressively faulted Opalinus Clay using optical as well as scanning electron microscopy. We present an evolutionary model for scaly clay that is of interest in the evaluation of Opalinus Clay to host radioactive waste.

Description: Structure of Suasselkä Postglacial Fault in northern Finland obtained by analysis of local events and ambient seismic noise Nikita Afonin, Elena Kozlovskaya, Ilmo Kukkonen, and DAFNE/FINLAND Working Group Solid Earth Discuss., doi:10.5194/se-2016-90,2016 Manuscript under review for SE (discussion: open, 0 comments) Understanding inner structure of seismogenic faults and their ability to reactivate is particularly important in investigating continental intraplate seismicity regime. In our study we address this problem using analysis of local seismic events and ambient seismic noise recorded by the temporary DAFNE array in northern Fennoscandian Shield. The main purpose of the DAFNE/FINLAND passive seismic array experiment was to characterize the present-day seismicity of the Suasselkä post-glacial fault (SPGF) that was proposed as one potential target for the DAFNE (Drilling Active Faults in Northern Europe) project. The DAFNE/FINLAND array comprised the area of about 20 to 100 km and consisted of 8 short-period and 4 broad-band 3-component autonomous seismic stations installed in the close vicinity of the fault area. The array recorded continuous seismic data during September, 2011–May, 2013. Recordings of the array have being analyzed in order to identify and locate natural earthquakes from the fault area and to discriminate them from the blasts in the Kittilä Gold Mine. As a result, we found several dozens of natural seismic events originating from the fault area, which proves that the fault is still seismically active. In order to study the inner structure of the SPGF we use cross-correlation of ambient seismic noise recorded by the array. Analysis of azimuthal distribution of noise sources demonstrated that during the time interval under consideration the distribution of noise sources is close to the uniform one. The continuous data were processed in several steps including single station data analysis, instrument response removal and time-domain stacking. The data were used to estimate empirical Green’s functions between pairs of stations in the frequency band of 0.1–1 Hz and to calculate correspondent surface wave dispersion curves. The S-wave velocity models were obtained as a result of dispersion curves inversion. The results suggest that the area of the SPGF corresponds to a narrow region of low S-wave velocities surrounded by rocks with high S-wave velocities. We interpret this low velocity region as a non-healed mechanically weak fault damage zone (FDZ) that remained after the last major earthquake that occurred after the last glaciation.

Description: 4-D imaging of sub-second dynamics in pore-scale processes using real-time synchrotron X-ray tomography Katherine J. Dobson, Sophia B. Coban, Samuel A. McDonald, Joanna N. Walsh, Robert C. Atwood, and Philip J. Withers Solid Earth, 7, 1059-1073, doi:10.5194/se-7-1059-2016, 2016 State-of-the-art synchrotron x-ray imaging was used to observe micron scale transport processes in real time. The 20 Hz 3-D image acquisition rates give experimental data free from motion artefacts, and suitable for detailed quantitative analysis of the dynamic fluid distribution, flow pathways and processes. The method marks a major breakthrough in our ability to capture both sub-second and lower frequency non-equilibrium process in many geological or engineering systems.

Description: Studying local earthquakes in the area Baltic-Bothnia Megashear using the data of the POLENET/LAPNET temporary array Olga Usoltseva and Elena Kozlovskaya Solid Earth, 7, 1095-1108, doi:10.5194/se-7-1095-2016, 2016 We address the problem of seismicity in the intraplate area of northern Fennoscandia using the information on local events recorded by the POLENET/LAPNET seismic array. We relocate the seismic events, calculate a 3-D tomographic P wave velocity model of the uppermost crust and investigate a focal mechanism of the event. Our results demonstrate that the Baltic-Bothnia Megashear is an important large-scale, reactivated tectonic structure that has to be taken into account when estimating seismic hazard.

Description: Combined deep sampling and mass-based approaches to assess soil carbon and nitrogen losses due to land-use changes in karst area of southwestern China Yecui Hu, Zhangliu Du, Qibing Wang, and Guichun Li Solid Earth, 7, 1075-1084, doi:10.5194/se-7-1075-2016, 2016 We quantified the SOC and TN losses induced by land-use changes in a typical karst region of southwestern China. Converting from natural forest to croplands greatly led to SOC and TN losses (as higher as 37.8 %), but the magnitude depended on sampling depth and calculation method. We recommend to account for SOC and TN stocks on equivalent soil mass basis together with deep sampling. This study has significant implications on the projected land management in the degraded karst areas.

Description: Phase segmentation of X-ray computer tomography rock images using machine learning techniques: an accuracy and performance study Swarup Chauhan, Wolfram Rühaak, Hauke Anbergen, Alen Kabdenov, Marcus Freise, Thorsten Wille, and Ingo Sass Solid Earth, 7, 1125-1139, doi:10.5194/se-7-1125-2016, 2016 Machine learning techniques are a promising alternative for processing (phase segmentation) of 3-D X-ray computer tomographic rock images. Here the performance and accuracy of different machine learning techniques are tested. The aim is to classify pore space, rock grains and matrix of four distinct rock samples. The porosity obtained based on the segmented XCT images is cross-validated with laboratory measurements. Accuracies of the different methods are discussed and recommendations proposed.

Description: Pore-scale tomography and imaging: applications, techniques and recommended practice Matthias Halisch, Holger Steeb, Steven Henkel, and Charlotte M. Krawczyk Solid Earth, 7, 1141-1143, doi:10.5194/se-7-1141-2016, 2016 No abstract available.

Description: Active faulting, 3-D basin architecture and Plio-Quaternary structural evolution of extensional basins: a 4-D perspective on the central Apennine chain evolution, Italy Stefano Gori, Emanuela Falcucci, Chiara Ladina, Simone Marzorati, and Fabrizio Galadini Solid Earth Discuss., doi:10.5194/se-2016-103,2016 Manuscript under review for SE (discussion: open, 0 comments) We perfomed geological field survey and seimic recordings of ambient noise to study the evolution of a portion of the central Apennines, in central Italy, over the past few million years. The adopted approach and the analysis of the available information allowed to decipher how the investigated areas evolved, in terms of activity of the faults present there. We also defined that some of the investigated faults are no more major faults, i.e. they are no more able to produce strong earthquakes.

Description: Porosity and permeability determination of organic-rich Posidonia shales based on 3-D analyses by FIB-SEM microscopy Georg H. Grathoff, Markus Peltz, Frieder Enzmann, and Stephan Kaufhold Solid Earth, 7, 1145-1156, doi:10.5194/se-7-1145-2016, 2016 This study improves our understanding of the evolution of pores in shales for modelling transport properties. 3-D microscopy on early and postmature Posidonia Shales showed similar porosities and pore size distributions. Large isolated pore clusters are within carbonates and clay minerals. Pores form during maturation in the postmature-matrix-filling organic matter. Modelled permeabilities are lowest perpendicular to bedding. They decrease with increasing maturity and are comparable to experimental data.

Description: Arrested development – a comparative analysis of multilayer corona textures in metamorphic rocks Paula P. Ogilvie and Roger Lawrence R. L. Gibson Solid Earth Discuss., doi:10.5194/se-2016-97,2016 Manuscript under review for SE (discussion: open, 0 comments) Coronas are vital clues to the presence of arrested reaction in metamorphic rocks. We review formation mechanisms of coronas and approaches utilised to model their evolution in P - T - X space. Forward modelling employing calculated chemical potential gradients allows a far more nuanced understanding of the intricacies that govern metamorphic reaction. These models have critical implications for the limitations and opportunities coronas afford in interpreting the evolution of metamorphic terranes.

Description: Archie's law – a reappraisal Paul W. J. Glover Solid Earth, 7, 1157-1169, doi:10.5194/se-7-1157-2016, 2016 In 1942 Archie discovered equations which have been used ever since to calculate reserves of oil and gas around the world. Two equations exist, one which is theoretically justified, and one which is not. Unfortunately it is the one which is not justified that often gives the best results. This research examines the extent to which the two approaches give differing results, concluding that the Winsauer et al. form of Archie's equations is better for use with data containing systematic errors.

Description: Digital carbonate rock physics Erik H. Saenger, Stephanie Vialle, Maxim Lebedev, David Uribe, Maria Osorno, Mandy Duda, and Holger Steeb Solid Earth, 7, 1185-1197, doi:10.5194/se-7-1185-2016, 2016 Modern estimation of rock properties combines imaging with advanced numerical simulations, an approach known as digital rock physics (DRP). In this paper we suggest a specific segmentation procedure of X-ray micro-computed tomography data with two different resolutions for two sets of carbonate rock samples. These carbonates were already characterized in detail in a previous laboratory study, which we complement with nanoindentation experiments.

Description: Experimental sand burial affects seedling survivorship, morphological traits, and biomass allocation of Ulmus pumila var. sabulosa in the Horqin Sandy Land, China Jiao Tang, Carlos Alberto Busso, Deming Jiang, Ala Musa, Dafu Wu, Yongcui Wang, and Chunping Miao Solid Earth, 7, 1085-1094, doi:10.5194/se-7-1085-2016, 2016 In order to test the tolerance of sandy elm after emergence, an experiment was conducted to evaluate the changes of survivorship, morphological traits and biomass allocation buried by various experimental burial depths. The results showed that partial sand burial did not influence survivorship but increased seedling height, diameter, taproot length, total biomass, and relative growth rates. It decreased total leaf area and changed biomass allocation, transferring more biomass to aboveground.

Description: Simulating stress-dependent fluid flow in a fractured core sample using real-time X-ray CT data Tobias Kling, Da Huo, Jens-Oliver Schwarz, Frieder Enzmann, Sally Benson, and Philipp Blum Solid Earth, 7, 1109-1124, doi:10.5194/se-7-1109-2016, 2016 A method is introduced to implement medical CT data of a fractured sandstone under varying confining pressures into fluid flow simulations to reproduce experimental permeabilities. The simulation results reproduce plausible fracture flow features (e.g. flow channeling, fracture closing/opening) and approximate the actual permeabilities, which are affected by the CT resolution and compositional matrix heterogeneities. Additionally, some recommendations are presented concerning future studies.

Description: Effects of topsoil treatments on afforestation in a dry-Mediterranean climate (southern Spain) P. Hueso-González, J. F. Martínez-Murillo, and J. D. Ruiz-Sinoga Solid Earth Discuss., doi:10.5194/se-2016-98,2016 Manuscript under review for SE (discussion: open, 0 comments) The development of alternative low cost and low environmental impact revegetation methods is necessary for the effective management of Mediterranean forest environments. This research assessed the effects of five types of soil amendment on the success of afforestation processes. In terms of land management, the study shows that the addition of mulch or hydroabsorbent polymer can reduce transplanting stress, and improve the success of afforestation programs.

Description: X-ray computed tomography investigation of structures in Opalinus Clay from large-scale to small-scale after mechanical testing Annette Kaufhold, Matthias Halisch, Gerhard Zacher, and Stephan Kaufhold Solid Earth, 7, 1171-1183, doi:10.5194/se-7-1171-2016, 2016 The OPA material has been intensively studied by a variety of multiple scale and non-destructive 3-D X-ray CT investigations, following a consequent top-down approach to identify specific regions of interest. According to the mechanical experiment, it has been observed that the shear failure is located in a clay-rich area. Within the intersecting area of the two main fractures, a so called mylonitic zone with a particle reduction was observed on the open shear failure using CT and SEM techniques.

Description: Seismic structure beneath the Gulf of Aqaba and adjacent areas based on the tomographic inversion of regional earthquake data Sami El Khrepy, Ivan Koulakov, Nassir Al-Arifi, and Alexey G. Petrunin Solid Earth, 7, 965-978, doi:10.5194/se-7-965-2016, 2016 Three-dimensional seismic structures beneath the Gulf of Aqaba are presented for the first time for the southern part of the Dead Sea. A regional earthquake tomography method is applied to P and S waves data. The new results indicate new perspectives suggesting an oceanic nature of the crust in the northern part of the Red Sea, disagreeing with the hypothesis of a gradual stretching of the continental crust.

Description: A multi-stage 3D stress field modelling approach exemplified in the Bavarian Molasse Basin Moritz O. Ziegler, Oliver Heidbach, John Reinecker, Anna M. Przybycin, and Magdalena Scheck-Wenderoth Solid Earth Discuss., doi:10.5194/se-2016-92,2016 Manuscript under review for SE (discussion: open, 0 comments) Subsurface engineering relies on sparsely distributed datapoints of the stress state of the earth's crust. 3D geomechanical numerical modelling is applied to estimate the stress state in the entire volume of a large area. We present a multi-stage approach of differently sized models which provide the stress state in an area of interest derived from few and widely scattered data records. Furthermore we demonstrate the changes in reliability of the model depending on different input parameters.

Description: Defining a Mid-Holocene earthquake through speleoseismological and independent data: constraints for the outer Central Apennines (Italy) seismotectonic framework Alessandra Di Domenica and Alberto Pizzi Solid Earth Discuss., doi:10.5194/se-2016-77,2016 Manuscript under review for SE (discussion: open, 0 comments) Speleoseismological investigations have been adopted to characterize a complex tectonically active area in the easternmost sector of the Central Apennines. Evidence of earthquake damages have been recognized in the analyzed cave. Radiocarbon dating and the correspondence with independent data collected outside the cave, provide constraints for the individuation of a M~7 Mid-Holocene earthquake and for the identification of the nearby Sulmona normal fault as the most likely causative structure.

Description: Vegetation greenness response to water availability in northern China from 1982 to 2006 Fengtai Zhang and Youzhi An Solid Earth, 7, 995-1002, doi:10.5194/se-7-995-2016, 2016 The relationship between satellite-observed normalized difference vegetation index (NDVI) data as a proxy for vegetation greenness and water availability (rainfall and soil moisture) can greatly improve our understanding of how vegetation greenness responds to water availability fluctuations. Using Sen and Pearson’s correlation methods, we analyzed the spatiotemporal variation of vegetation greenness for both the entire year and the growing season (GS,4–10) in northern China from 1982 to 2006.

Description: 3D GPS velocity field and its implications on the present-day postorogenic deformation of the Western Alps and Pyrenees Hai Ninh Nguyen, Philippe Vernant, Stephane Mazzotti, Giorgi Khazaradze, and Eva Asensio Solid Earth Discuss., doi:10.5194/se-2016-78,2016 Manuscript under review for SE (discussion: open, 0 comments) We present a new 3D GPS velocity solution for 182 sites for the region encompassing the Western Alps, Pyrenees. The only significant horizontal deformation (0.2 mm yr −1 over a distance of 50 km) is a NNE-SSW extension in the western Pyrenees. In contrast, significant uplift rates up to 2 mm yr −1 occur in the Western Alps but not in the Pyrenees. A correlation between site elevations and fast uplift rates in the Western Alps suggests that part of this uplift is induced by postglacial rebound.

Description: Development of a numerical workflow based on μ -CT imaging for the determination of capillary pressure–saturation-specific interfacial area relationship in 2-phase flow pore-scale porous-media systems: a case study on Heletz sandstone Aaron Peche, Matthias Halisch, Alexandru Bogdan Tatomir, and Martin Sauter Solid Earth, 7, 727-739, doi:10.5194/se-7-727-2016, 2016 In this case study, we compute georeservoir specific capillary pressure-saturation- interfacial area relationships by implementing a FEM-based two-phase flow model on μ-CT-based modelling domains. We propose a recommended practice for deriving a model and model setup for the successful modelling of such types of problems on micro-CT obtained geometries.

Description: Geopotential field anomalies and regional tectonic features – two case studies: southern Africa and Germany Monika Korte and Mioara Mandea Solid Earth, 7, 751-768, doi:10.5194/se-7-751-2016, 2016 We investigated characteristics of magnetic anomalies over southern Africa (South Africa, Namibia, and Botswana) and Germany on different scales and also compared them to gravity gradient anomalies. Such anomalies provide information relevant to understanding geological and tectonic structures. Our results indicate a better agreement between anomalies caused by shallow and deeper structures in the southern African area than in the German area.

Description: Discussing the genesis of karst rocky desertification research based on the correlations between cropland and settlements in typical peak-cluster depressions Yang Bing Li, Qiong Yao Li, Guang Jie Luo, Xiao Yong Bai, Yong Yan Wang, Shi Jie Wang, Jing Xie, and Guang Bin Yang Solid Earth, 7, 741-750, doi:10.5194/se-7-741-2016, 2016 In karst mountainous areas in Southwest China, sloping land is overly reclaimed. Why are farmers doing this? Through typical case studies of peak-cluster depression areas, we found that low land carrying capacity and high population pressure where farmers carry out extreme steep reclamation activities are the main reasons for desert-like landscapes; this is a kind of land degradation which occurs in vulnerable karst dryland socioecological systems.

Description: The Pollino 2012 seismic sequence: clues from continuous radon monitoring Antonio Piersanti, Valentina Cannelli, and Gianfranco Galli Solid Earth Discuss., doi:10.5194/se-2016-72,2016 Manuscript under review for SE (discussion: open, 0 comments) We investigate in an innovative way the dynamics of radon emanation in a seismically active area. We analyzed three years of data, collected during a long term radon monitoring experiment. The complexity of the relationships among the investigated variables led us to consider the problem both from a phenomenological point of view and by means of original numerical analyses. Different approaches converge on the existence of a physical relation between soil radon emanation and seismicity.

Description: Nitrogen and Warming Control the Vegetation in Inner Mongolia Tourist Area Qiong Sun, Xiaobing Hu, and Chi Zhang Solid Earth Discuss., doi:10.5194/se-2016-52,2016 Manuscript under review for SE (discussion: open, 0 comments) The global warming and atmospheric nitrogen deposition problem has become more and more serious under the influence of human activities, and it has become one of the hot issues in this field, which will have far-reaching impact on all kinds of vegetation, thus the functioning of the ecosystem will be changed, which will be reflected in climate warming process. Inner Mongolia Autonomous Region is mainly composed of desert grasslands, so the development and protection of vegetation has considerable significance on the region. However, in the current environment of global warming, few studies have been carried out on desert grassland plants. In this paper, an in-depth study was carried out on the impact of warming and nitrogen addition on soil temperature, vegetation reproductive phenology and vegetation community seed rain under natural conditions during five-year period from 2011 to 2015. During the experimental period, we found that soil temperature and soil moisture decreased with the increase of soil layer, and warming obviously shortened the time of budding, flowering and fruiting of vegetation. However, no significant effect was found on nitrogen addition. Meanwhile, the impact of interaction effect of warming and nitrogen addition on seed rain was not obvious, but the year difference of all relevant indicators was significant.

Description: Fixation kinetics of chelated and non-chelated zinc in semi-arid alkaline soils: application to zinc management Theophilus K. Udeigwe, Madeleine Eichmann, and Matthew C. Menkiti Solid Earth, 7, 1023-1031, doi:10.5194/se-7-1023-2016, 2016 Micronutrient fixation leads to the reduction of plant-available portions. This study examined the fixation kinetics of chelated and non-chelated zinc (Zn) in semi-arid soils. About 30 % more Zn was fixed in the non-chelated system in the first 14 days. Slope of change of Zn to Cu (i.e., Cu–Zn) was higher than other micronutrients. Zn fixation kinetics were better described by a power-function model. Tools developed from this study will be used to advance micronutrient management.

Description: sUAS and their application in observing geomorphological processes Jozef Gallik and Lenka Bolešová Solid Earth, 7, 1033-1042, doi:10.5194/se-7-1033-2016, 2016 Technology is moving ahead very fast, and so researchers have new possibilities for their research. We tried to demonstrate benefits of using remote-sensing technology (Phantom 1 drone) such as its accuracy in the terrain, easy access to hardly accessible areas, and the possibility to collect data even during unfavourable weather conditions. The high mountainous environment provided us great conditions for testing the drone as a device for very easy and accurate mapping of natural phenomena.

Description: Alpine tectonic wedging and crustal delamination in the Cantabrian Mountains (NW Spain) Jorge Gallastegui, Javier A. Pulgar, and Josep Gallart Solid Earth, 7, 1043-1057, doi:10.5194/se-7-1043-2016, 2016 We present the interpretation of deep seismic reflection profile ESCIN-2 across the boundary between the Cantabrian Mountains and the Cenozoic Duero Basin (NW Spain). 2-D seismic modelling allowed us to construct a N-S geological cross section which is compatible with the rest of the geophysical data. This profile shows the importance of the N-S Alpine deformation. A wedge of Cantabrian margin crust indented southwards into the delaminated Iberian crust, forcing its northward subduction.

Description: Stepwise drying of Lake Turkana at the end of the African Humid Period: an example of forced regression modulated by solar activity? Alexis Nutz and Mathieu Schuster Solid Earth Discuss., doi:10.5194/se-2016-95,2016 Manuscript under review for SE (discussion: open, 0 comments) From the geomorphology of a paleo-delta complex of Lake Turkana (Kenya), we explore the end of the Holocene African Humid Period (AHP) that corresponded to a major change in climate of Africa and that had important environmental impacts. Here, we propose that the transition from a wet to a dry period at the end of the AHP is stepwise, discussing a potential control by short-term evolution of solar activity. Understanding of this climate event is crucial to anticipate a future climate change.

Description: 3-D reflection seismic imaging of the Hontomín structure in the Basque-Cantabrian Basin (Spain) Solid Earth Discussions, 5, 1575-1614, 2013 Author(s): J. Alcalde, D. Martí, C. Juhlin, A. Malehmir, D. Sopher, E. Saura, I. Marzán, P. Ayarza, A. Calahorrano, A. Pérez-Estaún, and R. Carbonell The Basque-Cantabrian Basin of the Northern Iberia peninsula constitutes a unique example of a major deformation system, featuring a dome structure developed by extensional tectonics followed by compressional reactivation. The occurrence of natural resources in the area and the possibility of establishing a geological storage site for carbon dioxide motivated the acquisition of a 3-D seismic reflection survey in 2010, centered on the Jurassic Hontomín dome. The objectives of this survey were to obtain a geological model of the overall structure and to establish a baseline model for a possible geological CO 2 storage site. The 36 km 2 survey included approximately 5000 mixed (Vibroseis and explosives) source points recorded with a 25 m inline source and receiver spacing. The target reservoir is a saline aquifer, at approximately 1450 m depth, encased and sealed by carbonate formations. Acquisition and processing parameters were influenced by the rough topography and relatively complex geology. A strong near surface velocity inversion is evident in the data, affecting the quality of the data. The resulting 3-D image provides constraints on the key features of the geologic model. The Hontomín structure is interpreted to consist of an approximately 10 7 m 2 large elongated dome with two major W–E and NW–SE striking faults bounding it.

Description: Review of some significant claimed irregularities in Scandinavian postglacial uplift in time scales from tens to thousands of years: earthquakes? Solid Earth Discussions, 5, 1615-1640, 2013 Author(s): S. Gregersen The postglacial uplift/subsidence in Scandinavia is regular. And the phenomenon is similar in time scales of tens, hundreds and thousands of years studied via geodesy, seismology and geology. Searches for irregularities in the form of earthquakes claimed in the scientific literature have disclosed many earthquakes right after the Ice Age and some later cases for further evaluation. In a previous report the present author has mentioned doubts about the validity of some of the most significant claimed irregularities. In the present paper a review is made of these significant claimed irregularities in the southwestern flank of the Scandinavian postglacial uplift/subsidence via literature studies of geodetic and geological claims of earthquakes as well as discussions in the field. Geodetic observations exist for all of Scandinavia. Those describe the phenomenon in 10s–100s of years scale. Earthquake observations in seismology are of relevance in the same time scales. Geological studies of dated shore lines describe the postglacial vertical earth-surface motion in a quite different time scale of 100s–1000s of years. There is a need for integration of these observations geographically. This is happening in the various time scales in the DynaQlim project. The review finds the claims improbable about the following: (1) geodynamical motion in the Copenhagen area, (2) a paleo-earthquake in Læsø and (3) the recently proposed water level discrepancy in the southern part of Denmark. The assessment is less certain, but falls to improbable concerning (4) proposed paleo-earthquakes by Hallandsåsen in southwestern Sweden.

Description: 3-D geomechanical modelling of a gas reservoir in the North German Basin: workflow for model building and calibration Solid Earth Discussions, 5, 767-788, 2013 Author(s): K. Fischer and A. Henk The optimal use of conventional and unconventional hydrocarbon reservoirs depends, amongst others, on the local tectonic stress field. For example, wellbore stability, orientation of hydraulically induced fractures and – especially in fractured reservoirs – permeability anisotropies are controlled by the recent in situ stresses. Faults and lithological changes can lead to stress perturbations and produce local stresses that can significantly deviate from the regional stress field. Geomechanical reservoir models aim for a robust, ideally "pre-drilling" prediction of the local variations in stress magnitude and orientation. This requires a~numerical modelling approach that is capable to incorporate the specific geometry and mechanical properties of the subsurface reservoir. The workflow presented in this paper can be used to build 3-D geomechanical models based on the Finite Element Method (FEM) and ranging from field-scale models to smaller, detailed submodels of individual fault blocks. The approach is successfully applied to an intensively faulted gas reservoir in the North German Basin. The in situ stresses predicted by the geomechanical FE model were calibrated against stress data actually observed, e.g. borehole breakouts and extended leak-off tests. Such a validated model can provide insights into the stress perturbations in the inter-well space and undrilled parts of the reservoir. In addition, the tendency of the existing fault network to slip or dilate in the present-day stress regime can be addressed.

Description: Experimental study on the electrical conductivity of quartz andesite at high temperature and high pressure: evidence of grain boundary transport Solid Earth Discussions, 7, 1555-1576, 2015 Author(s): K. S. Hui, H. Zhang, H. P. Li, L. D. Dai, H. Y. Hu, J. J. Jiang, and W. Q. Sun In this study, the grain boundary conductivity of quartz andesite was in situ measured under conditions of 0.5–2.0 GPa and 723–973 K using a YJ-3000t multi-anvil press and Solartron-1260 Impedance/Gain-phase Analyzer. Experimental results indicate that grain interior transport controls the higher frequencies (10 2 –10 6 Hz), whereas the grain boundary process dominates the lower frequencies (10 −1 –10 2 Hz). At a given pressure and temperature range, the relationship between log σ and 1/ T conforms to an Arrhenius relation. As temperature increased, both of the grain boundary and grain interior conductivities of quartz andesite increased. Under increasing pressure, however, both of the grain boundary and grain interior conductivities of the sample decreased. By the virtue of the dependence of grain boundary conductivity on pressure, the activation enthalpy and the activation volume were calculated at 0.77–1.03 eV and 5.29 ± 1.94 cm 3 mol −1 , respectively. Furthermore, the small polaron conduction mechanism between the ferrous and ferric ion is also discussed.

Description: Land use effects on soil organic carbon sequestration in calcareous leptosols in former pastureland – a case study from the Tatra Mountains (Poland) Solid Earth Discussions, 7, 1577-1610, 2015 Author(s): K. Wasak and M. Drewnik The purpose of the paper is to show SOC sequestration rates in calcareous shallow soils in reforested areas in Tatra Mts. with a particular focus on the different forms of organic matter (OM) storage. Three plant communities creating a mosaic on the slopes of the valley were taken into account. After 50 years since the conversion of pastureland to grassland, dwarf pine shrub, and larch forest on soils, the development of genetic soil horizons as well as SOC sequestration in soil occur despite the steepness of slopes. SOC stock is the highest in soils under larch forest (63.5 mg ha −1 , SD 16.3), while in soil under grassland and under dwarf pine shrub, this value is smaller (47.5 mg ha −1 , SD 13.3 and 42.9 mg ha −1 , SD 22.0 respectively). The highest amount of mineral-associated OM inside stable microaggregates (MOM FF3) is found in grassland soil (21.9–27.1% of SOC), less under dwarf pine shrub (16.3–19.3% of SOC) and larch forest (15.3–17.7% of SOC). The pool of mineral-associated OM inside transitional macroaggregates (MOM FF2) is found in soil under dwarf pine shrub (39.2–59.2% of SOC), with less under larch forest (43.8–44.7% of SOC) and the least in grassland soil (37.9–41.6% of SOC). The highest amount of the free light particulate fraction (POM LF1) is found in soil under dwarf pine shrub (6.6–10.3% of SOC), with less under larch forest (2.6–6.2% of SOC) and the least in grassland soil (1.7–4.8% of SOC).

Description: Eliciting geologists' tacit model of the uncertainty of mapped geological boundaries Solid Earth Discussions, 7, 147-184, 2015 Author(s): R. M. Lark, R. S. Lawley, A. J. M. Barron, D. T. Aldiss, K. Ambrose, A. H. Cooper, J. R. Lee, and C. N. Waters It is generally accepted that geological linework, such as mapped boundaries, are uncertain for various reasons. It is difficult to quantify this uncertainty directly, because the investigation of error in a boundary at a single location may be costly and time consuming, and many such observations are needed to estimate an uncertainty model with confidence. However, it is also recognized across many disciplines that experts generally have a tacit model of the uncertainty of information that they produce (interpretations, diagnoses etc.) and formal methods exist to extract this model in usable form by elicitation. In this paper we report a trial in which uncertainty models for mapped boundaries in six geological scenarios were elicited from a group of five experienced geologists. In five cases a consensus distribution was obtained, which reflected both the initial individually elicted distribution and a structured process of group discussion in which individuals revised their opinions. In a sixth case a consensus was not reached. This concerned a boundary between superficial deposits where the geometry of the contact is hard to visualize. The trial showed that the geologists' tacit model of uncertainty in mapped boundaries reflects factors in addition to the cartographic error usually treated by buffering linework or in written guidance on its application. It suggests that further application of elicitation, to scenarios at an appropriate level of generalization, could be useful to provide working error models for the application and interpretation of linework.

Description: Effects of pumice mining on soil quality Solid Earth Discussions, 7, 1375-1398, 2015 Author(s): A. Cruz-Ruíz, E. Cruz-Ruíz, R. Vaca, P. Del Aguila, and J. Lugo México is the worl's fourth most important maize producer; hence, there is a need to maintain soil quality for a sustainable production in the upcoming years. Pumice mining, a superficial operation, modifies large areas in Central Mexico. The main aim was to assess the present state of agricultural soils differing in elapsed-time since pumice mining (0–15 years), in a representative area of the Calimaya region in the State of Mexico. The study sites in 0, 1, 4, 10 and 15 year-old reclaimed soils were compared with adjacent undisturbed site. Our results indicate that soil organic carbon, total nitrogen, microbial biomass carbon and microbial quotients were greatly impacted by disturbance. A general trend of recovery towards the undisturbed condition with reclamation age was found after disturbance. Recovery of soil total nitrogen was faster than soil organic carbon. Principal components analysis was applied. The first three components together explain 71.72 % of the total variability. First factor reveals strong associations between total nitrogen, microbial biomass carbon and pH. The second factor reveals high loading of urease and catalase. The obtained results revealed that the most appropriate indicators to diagnose the quality of the soils were: total nitrogen, microbial biomass carbon and soil organic carbon.

Description: POLENET/LAPNET teleseismic P wave travel time tomography model of the upper mantle beneath northern Fennoscandia Hanna Silvennoinen, Elena Kozlovskaya, and Eduard Kissling Solid Earth, 7, 425-439, doi:10.5194/se-7-425-2016, 2016 POLENET/LAPNET broadband seismic network was deployed in northern Fennoscandia 2007–2009. In our study we estimate the 3D architecture of the upper mantle beneath the network using high-resolution teleseismic P-wave tomography. Our study reveals a highly heterogeneous lithospheric mantle. The most significant feature seen in the obtained velocity model is a large elongated low-velocity anomaly beneath the crust, separating the three cratonic units that formed the region in the early Proterozoic.

Description: Calculating structural and geometrical parameters by laboratory measurements and X-ray microtomography: a comparative study applied to a limestone sample before and after a dissolution experiment Linda Luquot, Vanessa Hebert, and Olivier Rodriguez Solid Earth, 7, 441-456, doi:10.5194/se-7-441-2016, 2016 To evaluate oil and gas production, accurate characterization (usually based on laboratory experiments) of reservoir rock properties needs to be performed. X-ray scanning samples enable obtaining 3-D images of the rock inner structure from which those properties can be obtained using images processing. This article shows that these two approaches are complementary and yield consistent results. Moreover, image-based calculations allow to save a huge amount of time compared to lab-based measures.

Description: Phase Segmentation of X-Ray Computer Tomography Rock Images using Machine Learning Techniques: an Accuracy and Performance Study Swarup Chauhan, Wolfram Rühaak, Hauke Anbergen, Alen Kabdenov, Marcus Freise, Thorsten Wille, and Ingo Sass Solid Earth Discuss., doi:10.5194/se-2016-44,2016 Manuscript under review for SE (discussion: open, 0 comments) Machine learning techniques are a promising alternative for processing (phase segmentation) of 3D X-Ray computer tomographic (XCT) rock images. Here, the performance and accuracy of different machine learning techniques is tested. Aim is to classify pore space, rock grains and matrix of four distinct rock samples. The porosity obtained based on the segmented XCT images is cross-validated with laboratory measurements. Accuracies of the different methods are discussed and recommendation proposed.

Description: The Mohr–Coulomb criterion for intact rock strength and friction – a re-evaluation and consideration of failure under polyaxial stresses Abigail Hackston and Ernest Rutter Solid Earth, 7, 493-508, doi:10.5194/se-7-493-2016, 2016 This was an experimental study of the strength of two rock types, over a range of pressure conditions that correspond to depths in the Earth’s crust ranging up to 12 km. Tests were carried out under different stress regimes to simulate extremes of the range of loading geometries encountered in the Earth and hence how these affect failure strength and resistance to frictional slip on faults. These experiments will promote understanding of rock behaviour in oil, gas and water reservoirs.

Description: Tectonothermal evolution in the core of an arcuate fold and thrust belt: the southeastern sector of the Cantabrian Zone (Variscan belt, NW Spain) M. L. Valín, S. García-López, C. Brime, F. Bastida, and J. Aller Solid Earth Discuss., doi:10.5194/se-2016-53,2016 Manuscript under review for SE (discussion: open, 0 comments) Abstract. The tectonothermal evolution of an area located in the core of the Ibero-Armorican arc (Variscan belt) has been determined by using the conodont color alteration index (CAI), Kübler index of illite (KI), the Árkai index of chlorite (AI), and the analysis of clay minerals and rock cleavage. The area is part of the Cantabrian Zone (CZ), which represents the foreland fold and thrust belt of the orogen. It has been thrust by several large units of the CZ, what resulted in the generation of a large amount of synorogenic Carboniferous sediments. CAI, KI and AI values show an irregular distribution of metamorphic grade, independent of stratigraphic position. Two tectonothermal events have been distinguished in the area. The first one, poorly defined, is mainly located in the northern part. It gave rise to very low-grade metamorphism in some areas and it was associated with a deformation event that resulted in the emplacement of the last large thrust unit and development of upright folds and associated cleavage (S 1 ).The second tectonothermal event gave rise to low-grade metamorphism and cleavage (S 2 ) crosscutting earlier upright folds in the central, western and southern parts of the study area. The event continued with the intrusion of small igneous rock bodies, which gave rise to contact metamorphism and hydrothermal alteration. The second event was linked to an extensional episode due to a gravitational instability at the end of the Variscan deformation. This tectonothermal evolution occurred during the Gzhelian-Sakmarian. Subsequently, several hydrothermal episodes took place, in association with local development of crenulation cleavage during the Alpine deformation.

Description: Development of a numerical workflow based on μ-CT-imaging for the determination of capillary pressure-saturation-specific interfacial area relationship in two-phase flow pore-scale porous media systems: A case study on Heletz sandstone Aaron Peche, Matthias Halisch, and Alexandru Bogdan Tatomir Solid Earth Discuss., doi:10.5194/se-2016-39,2016 Manuscript under review for SE (discussion: open, 0 comments) In this case study, we compute georeservoir specific capillary pressure-saturation- interfacial area relationships by implementing a FEM-based two-phase flow model on μ-CT-based modelling domains. We propose a recommended practice for deriving a model and model setup for the successful modelling of such types of problems on micro-CT obtained geometries.

Description: 3-D visualisation of palaeoseismic trench stratigraphy and trench logging using terrestrial remote sensing and GPR – a multiparametric interpretation Sascha Schneiderwind, Jack Mason, Thomas Wiatr, Ioannis Papanikolaou, and Klaus Reicherter Solid Earth, 7, 323-340, doi:10.5194/se-7-323-2016, 2016 Palaeoseismological research uses historical earthquakes to verify seismic hazard assessment. Earthquakes of magnitude M 〉 5.5 likely produce surface ruptures that can be preserved in the subsurface. Buried soils or progressive displacements are the main targets of trenching studies. However, the recognition of these features is challenging for inexperienced researchers. Here a workflow is presented which applies remote sensing and geophysical techniques to verify layer distinction.

Description: Visualization and Quantification of the Penetration Behavior of Bentonite Suspensions into the Pore Network of non-cohesive Media by using μ-CT Imaging Britta Schoesser, Atefeh Ghorbanpour, Matthias Halisch, and Markus Thewes Solid Earth Discuss., doi:10.5194/se-2016-42,2016 Manuscript under review for SE (discussion: open, 0 comments) In summary, the µ-CT technique delivers a valuable contribution for the research on the interaction of bentonite suspensions penetration the pore space of non-cohesive media. This study shows the missing visual evidence concerning the theoretical interaction models of the bentonite suspension in the pore space on microscale. The Imaging results have been cross-validated with laboratory experiments and are in good agreement with each other.

Description: Strain localization in ultramylonitic marbles by simultaneous activation of dislocation motion and grain boundary sliding (Syros, Greece) A. Rogowitz, J. C. White, and B. Grasemann Solid Earth, 7, 355-366, doi:10.5194/se-7-355-2016, 2016 This paper discusses the processes resulting in extreme strain localization (gamma up to 1000) in an almost pure calcite marble located in Syros, Greece. We observed grain size reduction by bulging recrystallization, followed by the simultaneous activation of grain boundary sliding and a dislocation motion in conditions (high differential stress, high strain rate, low temperature) in which brittle deformation rather than ductile flow might be suspected.

Description: On the mechanical behaviour of a low angle normal fault: the Altotiberina fault (Northern Apennines, Italy) system case study Luigi Vadacca, Emanuele Casarotti, Lauro Chiaraluce, and Massimo Cocco Solid Earth Discuss., doi:10.5194/se-2016-48,2016 Manuscript under review for SE (discussion: open, 0 comments) Geological and seismological observations have been used to parameterize 2D numerical models to simulate the interseismic deformation of a complex extensional fault system located in the Northern Apennines (Italy). The geological system is dominated by the presence of the Altotiberina fault (ATF), a large (60 km along strike) low-angle normal fault 20° dipping in the brittle crust (0–15 km). The ATF is currently interested by a high and constant rate of microseismic activity and no moderate-to-large magnitude earthquakes have been associated to it for the past 1000 years. Modelling results have been compared with GPS data in order to understand the mechanical behaviour of this fault and a suite of minor syn- and antithetic normal fault segments located in the main fault hanging-wall. The results of the simulations demonstrate the active role played by the Altotiberina fault in accommodating the on going tectonic extension in this sector of the chain. The GPS velocity profile constructed through the fault system cannot be explained without including the ATF's contribution to deformation, indicating that this fault although misoriented has to be considered tectonically active and with a creeping behaviour below 5 km of depth. The low angle normal fault also shows a high degree of tectonic coupling with its main antithetic fault (the Gubbio fault) suggesting that creeping along the ATF may control the observed strain localization and the pattern of microseismic activity.

Description: Vegetation greenness response to water availability in northern China from 1982 to 2006 Zhang Fengtai and An Youzhi Solid Earth Discuss., doi:10.5194/se-2016-46,2016 Manuscript under review for SE (discussion: open, 0 comments) An evaluation of the relationship between satellite-observed Normalized Difference Vegetation Index (NDVI) data as a proxy for vegetation greenness and water availability (rainfall and soil moisture) can greatly improve our understanding of how vegetation greenness responds to water availability fluctuations. Using Sen and Pearson’s correlation methods, we analyzed the spatio-temporal variation of vegetation greenness for both the entire year and the growing season (GS,4-10) in northern China from 1982 to 2006. Although, vegetation greenness and soil moisture during the study period changed significantly for the entire study area, there was no change in rainfall. Linear correlation analysis between NDVI and rainfall revealed higher correlations using data for all seasons. Higher correlations for NDVI and soil moisture were obtained using growing season data. This study highlights how strongly vegetation greenness responds to water availability dynamics, especially in the growing season period.

Description: Multi-phase classification by a least-squares support vector machine approach in tomography images of geological samples Faisal Khan, Frieder Enzmann, and Michael Kersten Solid Earth, 7, 481-492, doi:10.5194/se-7-481-2016, 2016 X-ray microtomography image processing involves artefact reduction and image segmentation. The beam-hardening artefact is removed, applying a new algorithm, which minimizes the offsets of the attenuation data points. For the segmentation, we propose using a non-linear classifier algorithm. Statistical analysis was performed to quantify the improvement in multi-phase classification of rock cores using and without using our advanced beam-hardening correction algorithm.

Description: The effectiveness of jute and coir blankets for erosion control in different field and laboratory conditions Jana Kalibová, Lukáš Jačka, and Jan Petrů Solid Earth, 7, 469-479, doi:10.5194/se-7-469-2016, 2016 Jute and coir geotextiles (GTXs) significantly reduced the volume of surface run-off induced by simulated rainfall. “No-soil” conditions used during the laboratory experiment guarantee data based on GTX properties only. Contrary to our expectations, the performance ranking of GTXs in the laboratory did not match the field records. Soil did not influence all GTX samples equally. Further research may shed light on the variability of GTX effectiveness reported in available studies.

Description: The Subduction Dichotomy of Strong Plates and Weak Slabs Robert I. Petersen, Dave R. Stegman, and Paul J. Tackley Solid Earth Discuss., doi:10.5194/se-2016-56,2016 Manuscript under review for SE (discussion: open, 0 comments) In this study we propose a dichotomy in the strength profile of tectonic plates. This apparent dichotomy suggests that plates at the Earth's surface are significantly, orders of magnitude, stronger than the subducted slabs in the Earth's interior. Strong plates promote single sided, Earth-like subduction. Once subducted strong slabs transmit dynamic stresses and disrupt subduction. Slabs which are weakened do not disrupt subduction and furthermore exhibit a variety of observed morphologies.

Description: Archie's Law – A reappraisal Paul W. J. Glover Solid Earth Discuss., doi:10.5194/se-2016-47,2016 Manuscript under review for SE (discussion: open, 0 comments) In 1942 Archie examined data on the electrical properties of rocks containing oil and discovered equations which have been used ever since to calculate reserves of oil and gas around the world. Two equations exist, one which is theoretically justified, and one which is not. Unfortunately it is the one which is not justified that often gives the best results. It was the goal of this research to discover the extent to which the two approaches give differing results and to find the reason why.

Description: Feathery and network-like filamentous textures as indicators for the crystallization of quartz from a silica gel precursor at the Rusey Fault, Cornwall, UK Tim I. Yilmaz, Florian Duschl, and Danilo Di Genova Solid Earth Discuss., doi:10.5194/se-2016-61,2016 Manuscript under review for SE (discussion: open, 1 comment) Quartz crystals from a hydrothermal shear-zone-hosted quartz deposit (Rusey Fault, Cornwall, UK) show feathery textures and network-like filamentous textures. Optical hot-cathodoluminescence (CL) analysis and LA-ICP-MS investigations on quartz samples revealed that positions exhibiting feathery textures (violet luminescence) incorporate higher amounts of Ca, As, Na, Mg, and K than quartz positions without feathery textures (blue luminescence). Raman spectroscopy investigations revealed the presence of a weak peak ("shoulder") at 507–509 cm −1 in quartz affected by feathery textures, which we attribute to the presence of moganite, a microcrystalline silica variety. The combined occurrence of feathery textures and network-like filamentous textures in quartz samples from the Rusey fault zone points to the presence of a silica gel precursor before or during the crystallization.

Description: Combined deep sampling and mass-based approaches to assess soil carbon and nitrogen losses due to land-use changes in karst area of Southwestern China Yecui Hu, Zhangliu Du, Qibing Wang, and Guichun Li Solid Earth Discuss., doi:10.5194/se-2016-57,2016 Manuscript under review for SE (discussion: open, 0 comments) We quantified the SOC and TN losses induced by land-use changes in a typical karst region of southwestern China. Converting from natural forest to croplands greatly led to SOC and TN losses (as higher as 37.8 %), but the magnitude depended on sampling depth and calculation method. We recommend to account for SOC and TN stocks on equivalent soil mass basis together with deep sampling. This study has significant implications on the projected land management in the degraded karst areas.

Description: 〈b〉Seismic imaging of dyke swarms within the Sorgenfrei–Tornquist Zone (Sweden) and implications for thermal energy storage〈/b〉〈br〉 Alireza Malehmir, Bo Bergman, Benjamin Andersson, Robert Sturk, and Mattis Johansson〈br〉 Solid Earth, 9, 1469-1485, https://doi.org/10.5194/se-9-1469-2018, 2018〈br〉 Interest and demand for green-type energy usage and storage are growing worldwide. Among several, thermal energy storage that stores energy (excess heat or cold) in fluids is particularly interesting. For an upscaling purpose, three seismic profiles were acquired within the Tornquist suture zone in the southwest of Sweden and historical crustal-scale offshore BABEL lines revisited. A number of dykes have been imaged and implications for the storage and tectonic setting within the zone discussed.

Description: 〈b〉The influence of detachment strength on the evolving deformational energy budget of physical accretionary prisms〈/b〉〈br〉 Jessica McBeck, Michele Cooke, Pauline Souloumiac, Bertrand Maillot, and Baptiste Mary〈br〉 Solid Earth, 9, 1421-1436, https://doi.org/10.5194/se-9-1421-2018, 2018〈br〉 In order to assess the influence of deformational processes within accretionary prisms, we track the evolution of the energy budget. We track the consumption of energy stored in internal deformation of the host rock, energy expended in frictional slip, energy used in uplift against gravity and total energy input. We find that the energy used in internal deformation is 〈 1% of the total and that the energy expended in frictional slip is the largest portion of the budget.

Description: 〈b〉New insights on the early Mesozoic evolution of multiple tectonic regimes in the northeastern North China Craton from the detrital zircon provenance of sedimentary strata〈/b〉〈br〉 Yi Ni Wang, Wen Liang Xu, Feng Wang, and Xiao Bo Li〈br〉 Solid Earth, 9, 1375-1397, https://doi.org/10.5194/se-9-1375-2018, 2018〈br〉 Early Triassic sediments in the northeastern North Chian Craton resulted from the subduction of the Paleo-Asian oceanic plate and collision between the North China and Yangtze cratons. Late Triassic sediments resulted from the final closure of the Paleo-Asian Ocean in the Middle Triassic and exhumation of the Su–Lu Orogenic Belt. Early Jurassic change in provenance was related to the uplift of the Xing'an–Mongolia Orogenic Belt and the subduction of the Paleo-Pacific Plate.

Description: 〈b〉From widespread Mississippian to localized Pennsylvanian extension in central Spitsbergen, Svalbard〈/b〉〈br〉 Jean-Baptiste P. Koehl and Jhon M. Muñoz-Barrera〈br〉 Solid Earth, 9, 1535-1558, https://doi.org/10.5194/se-9-1535-2018, 2018〈br〉 This research is dedicated to the study of poorly understood coal-bearing Mississippian (ca. 360–325 Ma) sedimentary rocks in central Spitsbergen. Our results suggest that these rocks were deposited during a period of widespread extension involving multiple fault trends, including faults striking subparallel to the extension direction, while overlying Pennsylvanian rocks (ca. 325–300 Ma) were deposited during extension localized along fewer, larger faults.

Description: 〈b〉Soil erodibility and its influencing factors on the Loess Plateau of China: a case study in the Ansai watershed〈/b〉〈br〉 Wenwu Zhao, Hui Wei, Lizhi Jia, Stefani Daryanto, Xiao Zhang, and Yanxu Liu〈br〉 Solid Earth, 9, 1507-1516, https://doi.org/10.5194/se-9-1507-2018, 2018〈br〉 Soil erodibility (〈i〉K〈/i〉) is one of the key factors of soil erosion. Selecting the optimal estimation method of soil erodibility is critical to estimate the amount of soil erosion, and provide the base for sustainable land management. This research took the Loess Plateau of China as a case study, estimated soil erodibility factor with different methods, selected the best texture-based method to estimate 〈i〉K〈/i〉, and aimed to understand the indirect environmental factors of soil erodibility.

Description: 〈b〉The effect of rock composition on muon tomography measurements〈/b〉〈br〉 Alessandro Lechmann, David Mair, Akitaka Ariga, Tomoko Ariga, Antonio Ereditato, Ryuichi Nishiyama, Ciro Pistillo, Paola Scampoli, Fritz Schlunegger, and Mykhailo Vladymyrov〈br〉 Solid Earth, 9, 1517-1533, https://doi.org/10.5194/se-9-1517-2018, 2018〈br〉 Muon tomography is a technology, similar to X-ray tomography, to image the interior of an object, including geologically interesting ones. In this work, we examined the influence of rock composition on the physical measurements, and the possible error that is made by assuming a too-simplistic rock model. We performed numerical simulations for a more realistic rock model and found that beyond 300 m of rock, the composition starts to play a significant role and has to be accounted for.

Description: 〈b〉Regional Pliocene Exhumation of the Lesser Himalaya in the Indus Drainage〈/b〉〈br〉 Peter D. Clift, Peng Zhou, Daniel F. Stockli, and Jerzy Blusztajn〈br〉 Solid Earth Discuss., https//doi.org/10.5194/se-2018-132,2018〈br〉 〈b〉Manuscript under review for SE〈/b〉 (discussion: open, 0 comments)〈br〉 Surface processes driven by climate have been linked to the tectonic evolution of mountain belts, with the Himalayas and Asian monsoon being a classic example. Sediments from the Arabian Sea now show an increase in erosion from the Karakoram between 17 and 9.5 Ma, followed by an increase in the relative flux from the Himalayas after 5.7 Ma and especially from the Lesser Himalayas after 1.9 Ma. Lack of correlation with climate histories suggests that tectonic forces dominate control over erosion.

Description: 〈b〉The crossdip correction as a tool to improve imaging of crooked line seismic data: A case study from the post-glacial Burträsk fault, Sweden〈/b〉〈br〉 Ruth A. Beckel and Christopher Juhlin〈br〉 Solid Earth Discuss., https//doi.org/10.5194/se-2018-120,2018〈br〉 〈b〉Manuscript under review for SE〈/b〉 (discussion: open, 0 comments)〈br〉 Scandinavia is crossed by extensive fault scarps that have likely been caused by huge earthquake when the ice sheets of the last glacial melted. Due to the inaccessibility of the terrain, reflection seismic data has to be collected along crooked lines which reduces the imaging quality unless special corrections are applied. We developed a new correction method that is very tolerant to noise and used it to improve the reflection image of the such a fault and refine its geological interpretation.

Description: 〈b〉Linked thick to thin – skinned inversion in the central Kirthar Fold Belt of Pakistan〈/b〉〈br〉 Ralph Hinsch, Chloé Asmar, Muhammad Nasim, Muhammad Asif Abbas, and Shaista Sultan〈br〉 Solid Earth Discuss., https//doi.org/10.5194/se-2018-137,2018〈br〉 〈b〉Manuscript under review for SE〈/b〉 (discussion: final response, 3 comments)〈br〉 We use surface and geophysical subsurface data to constrain the structure and evolution of the central Kirthar Fold belt, a mountain belt on the western margin of the Indian plate in Pakistan. It can be shown, that the extension phase prior to the collision of India with Asia has a major impact on how the rocks deform today. The inherited structures in the crystalline basement reactivate in opposite sense and complexly deform the sedimentary rocks that have deposited before collision.

Description: 〈b〉Submarine groundwater discharge site in the First Salpausselkä ice-marginal formation, south Finland〈/b〉〈br〉 Joonas J. Virtasalo, Jan F. Schröder, Samrit Luoma, Juha Majaniemi, Juha Mursu, and Jan Scholten〈br〉 Solid Earth Discuss., https//doi.org/10.5194/se-2018-131,2018〈br〉 〈b〉Manuscript under review for SE〈/b〉 (discussion: open, 1 comment)〈br〉 This study establishes the local stratigraphy and 3D aquifer geometry of a submarine groundwater discharge site in the Hanko Peninsula, south Finland. The study is based on a rich dataset of marine seismic profiles, multibeam and sidescan sonar images of the seafloor, and onshore ground-penetrating radar and refraction seismic profiles. The groundwater discharge takes place through meter scale pockmarks on the seafloor, confirmed by elevated radon concentrations in the overlying water.

Description: 〈b〉Formation of linear planform chimneys controlled by preferential hydrocarbon leakage and anisotropic stresses in faulted fine-grained sediments, offshore Angola〈/b〉〈br〉 Sutieng Ho, Martin Hovland, Jean-Philippe Blouet, Andreas Wetzel, Patrice Imbert, and Daniel Carruthers〈br〉 Solid Earth, 9, 1437-1468, https://doi.org/10.5194/se-9-1437-2018, 2018〈br〉 A newly discovered type of hydrocarbon leakage structure is investigated following the preliminary works of Ho (2013; et al. 2012, 2013, 2016): blade-shaped gas chimneys instead of classical cylindrical ones. These so-called 〈q〉Linear Chimneys〈/q〉 are hydraulic fractures caused by overpressured hydrocarbon fluids breaching cover sediments along preferential directions. These directions are dictated by anisotropic stresses induced by faulting in sediments and pre-existing salt-diapiric structures.

Description: Socio-economic modifications of the Universal Soil Loss Equation Solid Earth Discussions, 7, 1731-1759, 2015 Author(s): A. Erol, Ö. Koşkan, and M. A. Başaran While social scientists have long focused on socio-economic and demographic factors, physical modelers typically study soil loss using physical factors. In the current environment, it is becoming increasingly important to consider both approaches simultaneously for the conservation of soil and water, and the improvement of land use conditions. This study uses physical and socio-economic factors to find a coefficient that evaluates the combination of these factors. It aims to determine the effect of socio-economic factors on soil loss and, in turn, to modify the Universal Soil Loss Equation (USLE). The methodology employed in this study specifies that soil loss can be calculated and predicted by comparing the degree of soil loss in watersheds, with and without human influence, given the same overall conditions. A coefficient for socio-economic factors, therefore, has been determined based on adjoining watersheds (WS I and II), employing simulation methods. Combinations of C and P factors were used in the USLE to find the impact of their contributions on soil loss. The results revealed that these combinations provided good estimation of soil loss amounts for the second watershed, i.e. WS II, from the adjoining watersheds studied in this work. This study shows that a coefficient of 0.008 modified the USLE to reflect the socio-economic factors as settlement influencing the amount of soil loss in the watersheds studied.

Description: Impact of land management system on crop yields and soil fertility in Cameroon Solid Earth Discussions, 7, 1761-1796, 2015 Author(s): D. Tsozué, J. P. Nghonda, and D. L. Mekem The impact of direct-seeding mulch-based cropping systems (DMC), direct seeding (DS) and tillage seeding (TS) on Sorghum yields, soil fertility and the rehabilitation of degraded soils was evaluated in northern Cameroon. Field work consisted of visual examination, soil sampling, yield and rainfall data collection. Three fertilization rates (F1: 100 kg ha −1 NPK + 25 kg ha −1 of urea in DMC, F2: 200 kg ha −1 NPK + 50 kg ha −1 of urea in DMC and F3: 300 kg ha −1 NPK + 100 kg ha −1 of urea in DMC) were applied to each cropping system (DS, TS and DMC), resulting in nine experimental plots. Two types of chemical fertilizer were used (NPK 22.10.15 and urea) and applied each year from 2002 to 2012. Average Sorghum yields were 1239, 863 and 960 kg ha −1 respectively in DMC, DS and TS at F1, 1658, 1139 and 1192 kg ha −1 respectively in DMC, DS and TS at F2, and 2270, 2138 and 1780 kg ha −1 respectively in DMC, DS and TS at F3. pH values were 5.2 to 5.7 under DMC, 4.9 to 5.3 under DS and TS, and 5.6 in the control sample. High values of cation exchange capacity were recorded in the control sample, TS system and F1 of DMC. Base saturation rates, total nitrogen and organic matter contents were high in the control sample and the DMC than in the others systems. All studied soils were permanently not suitable for Sorghum due to the high percentage of nodules. F1 and F2 of the DS were currently not suitable, while F1 and F3 of DMC, F3 of DS and F1, F2 and F3 of TS were marginally suitable for Sorghum due to low soil pH values.

Description: Numerical models for ground deformation and gravity changes during volcanic unrest: simulating the hydrothermal system dynamics of an active caldera Solid Earth Discussions, 7, 2055-2107, 2015 Author(s): A. Coco, J. Gottsmann, F. Whitaker, A. Rust, G. Currenti, A. Jasim, and S. Bunney Ground deformation and gravity changes in active calderas during periods of unrest can signal an impending eruption and thus must be correctly interpreted for hazard evaluation. It is critical to differentiate variation of geophysical observables related to volume and pressure changes induced by magma migration from shallow hydrothermal activity associated with hot fluids of magmatic origin rising from depth. In this paper we present a numerical model to evaluate the thermo-poroelastic response of the hydrothermal system in a caldera setting by simulating pore pressure and thermal expansion associated with deep injection of hot fluids (water and carbon dioxide). Hydrothermal fluid circulation is simulated using TOUGH2, a multicomponent multiphase simulator of fluid flows in porous media. Changes in pore pressure and temperature are then evaluated and fed into a thermo-poroelastic model (one-way coupling), which is based on a finite-difference numerical method designed for axi-symmetric problems in unbounded domains. Based on data for the Campi Flegrei caldera (Italy), a series of simulations assess the influence of fluid injection rates and mechanical properties on the hydrothermal system, uplift and gravity. Heterogeneities in hydrological and mechanical properties associated with the presence of ring faults are a key determinant of the fluid flow pattern and consequently the geophysical observables. Peaks (in absolute value) of uplift and gravity change profiles computed at the ground surface are located close to injection points (namely at the centre of the model and fault areas). Temporal evolution of the ground deformation indicates that the contribution of thermal effects to the total uplift is almost negligible with respect to the pore pressure contribution during the first years of the unrest, but increases in time and becomes dominant after a long period of the simulation. After a transient increase over the first years of unrest, gravity changes become negative and decrease monotonically towards a steady state value. Since the physics of the investigated hydrothermal system is similar to any fluid-filled reservoir, such as oil fields or CO 2 reservoirs produced by sequestration, the generic formulation of the model will allow it to be employed in monitoring and interpretation of deformation and gravity data associated with other geophysical hazards that pose a risk to human activity.

Description: Predicting parameters of degradation succession processes of Tibetan Kobresia grasslands Solid Earth Discussions, 7, 2185-2211, 2015 Author(s): L. Lin, Y. K. Li, X. L. Xu, F. W. Zhang, Y. G. Du, S. L. Liu, X. W. Guo, and G. M. Cao In the past two decades, increasing human activity (i.e., overgrazing) in the Tibetan Plateau has strongly influenced plant succession processes, resulting in the degradation of alpine grasslands. Therefore, it is necessary to diagnose the degree of degradation to enable implementation of appropriate management for sustainable exploitation and protection of alpine grasslands. Here, we investigated environmental factors and plant functional group quantity factors (PFGs) during the alpine grassland succession processes. Principal component analysis (PCA) was used to identify the parameters indicative of degradation. We divided the entire degradation process into six stages. PFG types shifted from rhizome bunch grasses to rhizome plexus and dense plexus grasses during the degradation process. Leguminosae and Gramineae plants were replaced by Sedges during the advanced stages of degradation. The PFGs were classified into two reaction groups: the grazing-sensitive group, containing Kobresia humilis Mey, and Gramineae and Leguminosae plants, and the grazing-insensitive group, containing Kobresia pygmaea Clarke. The first group was correlated with live root biomass in the surface soil (0–10 cm), whereas the second group was strongly correlated with mattic epipedon thickness and K. pygmaea characteristics. The degree of degradation of alpine meadows may be delineated by development of mattic epipedon and PFG composition. Thus, meadows could be easily graded and their use adjusted based on our scaling system, which would help prevent irreversible degradation of important grasslands. Because relatively few environmental factors are investigated, this approach can save time and labor to formulate a conservation management plan for degraded alpine meadows.

Description: Alleviating aluminium toxicity on an acid sulphate soils in Peninsular Malaysia with application of calcium silicate Solid Earth Discussions, 7, 2903-2926, 2015 Author(s): A. A. Elisa, S. Ninomiya, J. Shamshuddin, and I. Roslan A study was conducted to alleviate Al toxicity of an acid sulphate soils collected from paddy cultivation area in Kedah, Peninsular Malaysia. For this purpose, the collected acid sulphate soils were treated with calcium silicate. The treated soils were incubated for 120 days in submerged condition in a glasshouse. Subsamples were collected every 30 days throughout the incubation period. Soil pH and exchangeable Al showed positive effect; soil pH increased from 2.9 to 3.5, meanwhile exchangeable Al was reduced from 4.26 to 0.82 cmol c kg −1 , which was well below the critical Al toxicity level for rice growth of 2 cmol c kg −1 . It was noted that the dissolution of calcium silicate (CaSiO 3 ) supplied substantial amount of Ca 2+ and H 4 SiO 4 2− ions into the soil, noted with increment in Si (silicate) content from 21.21 to 40 mg kg −1 at day 30 and reduction of exchangeable Al at day 90 from 4.26 to below 2 cmol c kg −1 . During the first 60 days of incubation, Si content was positively correlated with soil pH, while the exchangeable Al was negatively correlated with Si content. It is believed that the silicate anions released by calcium silicate were active in neutralizing H + ions that governs the high acidity (pH 2.90) of the acid sulphate soils. This scenario shows positive effect of calcium silicate to reduce soil acidity, therefore creates a favourable soil condition for good rice growth during its vegetative phase (30 days). Thus, application of calcium silicate to alleviate Al toxicity of acid sulphate soils for rice cultivation is a good soil amendment.

Description: Soil contaminations in landfill: a case study of the landfill in Czech Republic Solid Earth Discussions, 7, 2927-2952, 2015 Author(s): D. Adamcová, M. D. Vaverková, S. Bartoň, Z. Havlíček, and E. Břoušková Phytotoxicity test was determined to assess ecotoxicity of landfill soil. Sinapis alba L. was used as heavy metals bioindicator. Soil samples 1–8, which were taken from the landfill body, edge of the landfill body and its vicinity meet the limits for heavy metals Co, Cd, Pb, and Zn specified in the applicable legislation. Hg and Mn threshold values are not established in legislation, but values have been determined for the needs of the landfill operator. For heavy metals Cr, Cu, and Ni sample 2 exceeded the threshold values, which attained the highest values of all the samples tested for Cr, Cu and Ni. For Cr and Ni the values were several times higher than values of the other samples. The second highest values for Cr, Cu, and Ni showed sample 6 and 7. Both samples exceeded the set limits. An increase in plant biomass was observed in plants growing on plates with soil samples, but no changes in appearance, slow growth or necrotic lesions appeared. Ecotoxicity tests show that tested soils (concentration of 50 %) collected from the landfill body, edge of the landfill body and its vicinity reach high percentage values of germination capacity of seeds of Sinapis alba L. (101–137 %). At a concentration of 25 %, tested soil samples exhibit lower values of germination capacity; in particular samples 3 to 8, yet the seed germination capacity in all 8 samples of tested soils range between 86 and 137 %.

Description: Measuring and crust-correcting finite-frequency travel time residuals – application to southwestern Scandinavia Solid Earth Discussions, 7, 1909-1939, 2015 Author(s): M. L. Kolstrup and V. Maupin We present a data processing routine to compute relative finite-frequency travel time residuals using a combination of the Iterative Cross-Correlation and Stack (ICCS) algorithm and the MultiChannel Cross-Correlation method (MCCC). The routine has been tailored for robust measurement of P and S wave travel times in several frequency bands and for avoiding cycle-skipping problems at the shortest periods. We also investigate the adequacy of ray theory to calculate crustal corrections for finite-frequency regional tomography in normal continental settings with non-thinned crust. We find that ray theory is valid for both P and S waves at all relevant frequencies as long as the crust does not contain low-velocity layers associated with sediments at the surface. Reverberations in the sediments perturb the arrival times of the S waves and the long-period P waves significantly, and need to be accounted for in crustal corrections. The data processing routine and crustal corrections are illustated using data from a network in southwestern Scandinavia.

Description: Density structure and geometry of the Costa Rican subduction zone from 3-D gravity modeling and local earthquake data Solid Earth Discussions, 7, 1941-1977, 2015 Author(s): O. H. Lücke and I. G. Arroyo The eastern part of the oceanic Cocos Plate presents a heterogeneous crustal structure due to diverse origins and ages as well as plate-hot spot interactions which originated the Cocos Ridge, a structure that converges with the Caribbean Plate in southeastern Costa Rica. The complex structure of the oceanic plate directly influences the dynamics and geometry of the subduction zone along the Middle American Trench. In this paper an integrated interpretation of the slab geometry is presented based on three-dimensional density modeling of combined satellite and surface gravity data, constrained by available geophysical and geological data and seismological information obtained from local networks. The results show the continuation of steep subduction geometry from the Nicaraguan margin into Northwestern Costa Rica, followed by a moderate dipping slab under the Central Cordillera toward the end of the Central American Volcanic Arc. To the southeast end of the volcanic arc, our preferred model shows a steep, coherent slab that extends up to the landward projection of the Panama Fracture Zone. Overall, a gradual change in the depth of the intraplate seismicity is observed, reaching 220 km in the northwestern part, and becoming progressively shallower toward the southeast, where it reaches a terminal depth of 75 km. The changes in the terminal depth of the observed seismicity correlate with the increased density in the modeled slab. The absence of intermediate depth intraplate seismicity in the southeastern section and the higher densities for the subducted slab in this area, support a model in which dehydration reactions in the subducted slab cease at a shallower depth, originating an anhydrous and thus aseismic slab.

Description: Dilatant normal faulting in jointed cohesive rocks: a physical model study Michael Kettermann, Christoph von Hagke, Heijn W. van Gent, Christoph Grützner, and Janos L. Urai Solid Earth, 7, 843-856, doi:10.5194/se-7-843-2016, 2016 We present an analogue modeling study on the interaction of pre-existing joints and normal faults using cohesive powder. We vary the angle between joints and a rigid basement fault and analyze interpreted map-view photographs at maximum displacement for various parameters and compare to nature. Results show a clear effect of increasing angle between joints and faults on fault geometry, fracture density and connectivity. These information can help interpreting fractured layers in the subsurface.

Description: Fully probabilistic seismic source inversion – Part 2: Modelling errors and station covariances Simon C. Stähler and Karin Sigloch Solid Earth Discuss., doi:10.5194/se-2016-87,2016 Manuscript under review for SE (discussion: open, 0 comments) Seismic source inversion is the method of inferring the spatial orientation of an earthquake source from seismic records. The results come with large uncertainties, which we try to estimate with a Bayesian approach. We propose an empirical relationship for a likelihood function based on a large dataset of deterministic solutions. This allows to use the cross-correlation coefficient as a misfit criterion, which is better suited for waveform comparison than the popular root mean square or L 2 -norm.

Description: Ionospheric influence on the seismo-telluric current related to electromagnetic signals observed before the Wenchuan M S  = 8.0 earthquake Mei Li, Handong Tan, and Meng Cao Solid Earth Discuss., doi:10.5194/se-2016-89,2016 Manuscript under review for SE (discussion: open, 0 comments) The results got in this investigation probably give a supplementary to the problem of lithosphere-atmosphere-ionosphere electromagnetic coupling and it maybe also helps us to understand the "energy source" of the same problem. In addition, the ionosphere can facilitate the electromagnetic wave propagation, as if the detectability of the observing system is improved effectively, which makes it reasonable that sometimes electromagnetic signals are recorded at a seeming unreasonable distance.

Description: High-resolution shear wave reflection seismics as tool to image near-surface subrosion structures – a case study in Bad Frankenhausen, Germany Sonja Wadas, Ulrich Polom, and Charlotte Krawczyk Solid Earth Discuss., doi:10.5194/se-2016-91,2016 Manuscript under review for SE (discussion: open, 0 comments) Subrosion is the subsurface leaching of soluble rocks. It is a global phenomenon and a geohazard in urban areas, because it causes depressions and sinkholes. This is the case in the study area, the town of Bad Frankenhausen, in northern Thuringia, Germany. Using shear-wave reflection seismics we are able to image these structures at high resolution to a depth of ca. 100 m. We observe that the underground is strongly fractured and there are indications of cavities.

Description: Geoscientific process monitoring with positron emission tomography (GeoPET) Johannes Kulenkampff, Marion Gründig, Abdelhamid Zakhnini, and Johanna Lippmann-Pipke Solid Earth, 7, 1217-1231, doi:10.5194/se-7-1217-2016, 2016 Transport processes can be observed with input–output experiments, disregarding the impact of heterogeneities, or they can be modelled, based on structural images. In contrast, positron emission tomography (PET) directly yields the spatio-temporal distribution of tracer concentration. PET benefits from its molecular sensitivity together with a reasonable resolution. We illustrate its use with examples of process monitoring of advection and diffusion processes, and we discuss benefits and limits.

Description: The deep Earth origin of the Iceland plume and its effects on regional surface uplift and subsidence N. Barnett-Moore, R. Hassan, N. Flament, and R. D. Müller Solid Earth Discuss., doi:10.5194/se-2016-118,2016 Manuscript under review for SE (discussion: open, 0 comments) We use a 3D mantle flow model to investigate the evolution of the Iceland plume in the North Atlantic. Our results show that over the last ~ 100 Myr a remarkably stable pattern of mantle flow in the lowermost mantle made it an ideal plume nucleation site beneath the region. At the surface, the model plume compared to published observables indicates that its large plume head, ~ 2000 km in diameter, arriving beneath Western Greenland in the Paleocene, can account for widespread topographic uplift.

Description: Determination of critical pH and Al concentration of acidic Ultisols for wheat and canola crops Abdulaha-Al Baquy, Jiu-Yu Li, Chen-Yang Xu, Khalid Mehmood, and Ren-Kou Xu Solid Earth Discuss., doi:10.5194/se-2016-126,2016 Manuscript under review for SE (discussion: open, 1 comment) Al toxicity to plants and soil infertility in acidic soils are the main limiting factors for crop growth. To establish which acid soils need to be ameliorated for plant growth, the parameters of critical soil pH and soil Al concentration must be determined. The critical soil pH and exchangeable aluminium of two Ultisols for wheat and canola production were determined in this study. The results obtained will provide useful references for the utilization and management of acid soils.

Description: Spatial variability of some soil properties varies in oil palm ( Elaeis guineensis Jacq.) plantations of west coastal area of India Sanjib Kumar Behera, Kancherla Suresh, Bezawada Narsimha Rao, Ravi Kumar Mathur, Arvind Kumar Shukla, Kamireddy Manorama, Kummari Ramachandrudu, Parasa Harinarayana, and Chandra Prakash Solid Earth, 7, 979-993, doi:10.5194/se-7-979-2016, 2016 This study analyzed the spatial variability of some soil properties in surface and subsurface soil layers of oil palm plantations in the south Goa district of Goa situated in western coastal area of India. The studied soil properties in surface and subsurface layers varied widely. Geostatistical analysis revealed different spatial distribution patterns for the soil properties. The generated prediction maps are useful for site-specific soil nutrient management in the area.

Description: Preface: From orogenesis to geoscience in the service of society: the scientific legacy of Prof. Andrés Pérez-Estaún Joaquina Alvarez-Marrón, Fernando Bastida, Ernest Rutter, Ramon Carbonell, and Charlotte M. Krawczyk Solid Earth, 7, 1199-1205, doi:10.5194/se-7-1199-2016, 2016 No abstract.

Description: Cooperative effects of field traffic and organic matter treatments on some compaction-related soil properties Metin Mujdeci, Ahmet Ali Isildar, Veli Uygur, Pelin Alaboz, Husnu Unlu, and Huseyin Senol Solid Earth Discuss., doi:10.5194/se-2016-84,2016 Manuscript under review for SE (discussion: open, 1 comment) Organic matter addition is an efficient way of reducing the effects of field traffic. The depth dependent (0–10 and 10–20 cm) changes of some soil physical traits such as penetration resistance, bulk density and porosity as a function of tractor passes and organic matter addition to a clay soil. The enhancing effects of treatmenst on the investigated parameteres were C 〉 GM 〉 FYM). The increase in tramlines made the soil properties worse and corresponded with the type of organic matter.

Description: Post-glacial reactivation of the Bollnäs fault, central Sweden Solid Earth Discussions, 7, 2833-2874, 2015 Author(s): A. Malehmir, M. Andersson, S. Mehta, B. Brodic, R. Munier, J. Place, G. Maries, C. Smith, J. Kamm, M. Bastani, H. Mikko, and B. Lund Glacially induced intraplate faults are conspicuous in Fennoscandia where they reach trace lengths of up to 155 km with estimated magnitudes up to 8 for the associated earthquakes. While they are typically found in northern parts of Fennoscandia, there are a number of published accounts claiming their existence further south in Fennoscandia and even in northern central Europe. This study focuses on a prominent scarp discovered recently in LiDAR (light detection and ranging) imagery hypothesized to be from a post-glacial fault and located about 250 km north of Stockholm near the town of Bollnäs. The Bollnäs scarp strikes approximately north–south for about 12 km. The maximum vertical offset in the sediments across the scarp is 4–5 m with the western block being elevated relative to the eastern block. To investigate potential displacement in the bedrock and identify structures in it that are related to the scarp, we conducted a multidisciplinary geophysical investigation that included gravity and magnetic measurements, high-resolution seismics, radio-magnetotellurics (RMT), electrical resistivity tomography (ERT) and ground penetrating radar (GPR). Results of the investigations suggest a zone of low-velocity and high-conductivity in the bedrock associated also with a magnetic lineament that is offset horizontally about 50 m to the west of the scarp. The top of bedrock is found ~ 10 m below the surface on the eastern side of the scarp while about ~ 20 m below on its western side. This difference is due to the different thicknesses of the overlying sediments, accounting for the surface topography, while the bedrock surface is likely more or less at the same topographic level on both sides of the scarp. This makes an estimation of the bedrock displacement challenging if not impossible with our datasets. To explain this, we suggest that the Bollnäs scarp is likely associated with an earlier deformation zone, within a wide (〉 150 m), highly fractured and water-bearing zone that became active as a reverse fault after the latest Weichselian deglaciation.

Description: Examining the fixation kinetics of chelated and non-chelated copper micronutrient and the applications to micronutrient management in semi-arid alkaline soils Solid Earth Discussions, 7, 2875-2902, 2015 Author(s): T. K. Udeigwe, M. B. Eichmann, and M. C. Menkiti The relationship between the deficiency of a nutrient in plants and its total concentration in the soil is complex. This study examined and compared the fixation and fixation kinetics of copper (Cu) in chelated (Ethylene diamine tetraacetic acid, EDTA) and non-chelated mixed systems of micronutrients in the semi-arid soils of the Southern High Plains, US using findings from Cu extraction studies and kinetic models. Approximately, 22 % more Cu was fixed in the non-chelated system within the first 14 days with only 7 % difference between the two systems by day 90. Findings suggest a decrease in the effectiveness of chelated micronutrient over time, highlighting the significance of timing even when chelated micronutrients are applied. The strengths of the relationship of change in available Cu with respect to other micronutrients [iron (Fe), manganese (Mn), and zinc (Zn)] were higher in the non-chelated system ( R 2 : 0.68–0.94), compared to the chelated ( R 2 : 0.42–0.81) with slopes of 0.40 (Cu–Fe), 0.31 (Cu–Mn), and 1.04 (Cu–Zn) in the non-chelated system and 0.26 (Cu–Fe), 0.22 (Cu–Mn), and 0.90 (Cu–Zn) in the chelated. Reduction in the amount of available Cu was best described by the power function model ( R 2 = 0.91, SE = 0.081) in the non-chelated system and second order model ( R 2 = 0.95, SE = 0.010) in the chelated system. The applications generated from this study could be used as tools for improved micronutrient management and also provide baseline data for future work in other semi-arid/arid alkaline soils of the world. Findings are also more applicable to field settings, an improvement over related previous studies.

Description: A simple 3-D numerical model of thermal convection in Earth's growing inner core: on the possibility of the formation of the degree-one structure with lateral viscosity variations Solid Earth Discussions, 7, 3817-3841, 2015 Author(s): M. Yoshida An east-west hemispherically asymmetric structure for Earth's inner core has been suggested by various seismological evidence, but its origin is not clearly understood. Here, to investigate the possibility of an "endogenic origin" for the degree-one thermal/mechanical structure of the inner core, I performed new numerical simulations of thermal convection in the growing inner core. A setup value that controls the viscosity contrast between the inner core boundary and the interior of the inner core, Δη T , was taken as a free parameter. Results show that the degree-one structure only appeared for a limited range of Δη T ; such a scenario may be possible but is not considered probable for the real Earth. The degree-one structure may have been realized by an "exogenous factor" due to the planetary-scale thermal coupling among the lower mantle, the outer core, and the inner core, not by an endogenic factor due to the internal rheological heterogeneity.

Description: The Mohr–Coulomb criterion for intact rock strength and friction – a re-evaluation and consideration of failure under polyaxial stresses Solid Earth Discussions, 7, 3843-3883, 2015 Author(s): A. Hackston and E. Rutter Abstract Darley Dale and Pennant sandstones were tested under conditions of both axisymmetric shortening and extension normal to bedding. These are the two extremes of loading under polyaxial stress conditions. Failure under generalized stress conditions can be predicted from the Mohr–Coulomb failure criterion under axisymmetric compression conditions provided the best form of polyaxial failure criterion is known. The sandstone data are best reconciled using the Mogi (1967) empirical criterion. Fault plane orientations produced vary greatly with respect to the maximum compression direction in the two loading configurations. The normals to the Mohr–Coulomb failure envelopes do not predict the orientations of the fault planes eventually produced. Frictional sliding on variously inclined sawcuts and failure surfaces produced in intact rock samples was also investigated. Friction coefficient is not affected by fault plane orientation in a given loading configuration, but friction coefficients in extension were systematically lower than in compression for both rock types and could be reconciled by a variant on the Mogi (1967) failure criterion. Friction data for these and other porous sandstones accord well with the Byerlee (1977) generalization about rock friction being largely independent of rock type. For engineering and geodynamic modelling purposes, the stress-state dependent friction coefficient should be used for sandstones, but it is not known to what extent this might apply to other rock types.

Description: Estimations of soil fertility in physically degraded agricultural soils through selective accounting of fine earth and gravel fractions Mavinakoppa S. Nagaraja, Ajay Kumar Bhardwaj, G. V. Prabhakara Reddy, Chilakunda A. Srinivasamurthy, and Sandeep Kumar Solid Earth, 7, 897-903, doi:10.5194/se-7-897-2016, 2016 Three nutrient stock estimation methods, generalized soil mass (GSM), bulk-density-based soil mass (BDSM) and the proportion of fine earth volume (FEV) method, were compared to estimate organic C and major available nutrient stocks in physically degraded agricultural soils of southern India. The stocks were lowest using FEV method followed by GSM and BDSM method. The study highlights the importance of estimation methods to obtain realistic estimates for the development of degraded land areas.

Description: Desertification of forest, range and desert in Tehran province, affected by climate change Hadi Eskandari, Moslem Borji, Hassan Khosravi, and Tayebeh Mesbahzadeh Solid Earth, 7, 905-915, doi:10.5194/se-7-905-2016, 2016 Climate change has been identified as a leading human and environmental crisis of the twenty-first century. Drylands throughout the world have always undergone periods of degradation due to naturally occurring fluctuation in climate. Persistence of widespread degradation in arid and semiarid regions of Iran necessitates monitoring and evaluation. This paper aims to monitor the desertification trend in three types of land use, including range, forest and desert, affected by climate change in Tehran province for the 2000s and 2030s. For assessing climate change at Mehrabad synoptic station, the data of two emission scenarios, including A2 and B2, were used, utilizing statistical downscaling techniques and data generated by the Statistical DownScaling Model (SDSM). The index of net primary production (NPP) resulting from Moderate Resolution Imaging Spectroradiometer (MODIS) satellite images was employed as an indicator of destruction from 2001 to 2010. The results showed that temperature is the most significant driving force which alters the net primary production in rangeland, forest and desert land use in Tehran province. On the basis of monitoring findings under real conditions, in the 2000s, over 60 % of rangelands and 80 % of the forest were below the average production in the province. On the other hand, the long-term average changes of NPP in the rangeland and forests indicated the presence of relatively large areas of these land uses with a production rate lower than the desert. The results also showed that, assuming the existence of circumstances of each emission scenarios, the desertification status will not improve significantly in the rangelands and forests of Tehran province.