405 documents found in 345ms
# 1
Del Bello, Elisabetta • Taddeucci, Jacopo • Scarlato, Piergiorgio • Giacalone, Emanuele
Abstract: This data publication includes particle size distribution data of natural volcanic ash samples used as starting material for laboratory experiments simulating the aggregation/disaggregation of colliding volcanic ash particles. Full details of the experimental method can be found in Del Bello et. al. (2015) and in the data description file provided here. Here we report raw particle size distribution data obtained through separation analysis. Two types of volcanic ash were analysed: i) andesitic ash from the Sakurajima volcano (Japan), collected from July 2013 deposits (named Sak sample); ii) phonolitic ash collected from the basal fallout layer of the ~10 ka old Pomici Principali eruptive unit [Di Vito et al., 1999]) of the Campi Flegrei (named Ppa). For both compositions, 3 different starting materials were obtained by hand sieving the natural samples into three main particle size classes: (i) <32 μm, (ii) 32–63 μm, and (iii) 63–90 μm. For the phonolitic composition Ppa two additional starting materials were obtained by mixing the <32 μm and the 32–63 μm classes in known proportions. For each starting material, the grain size distribution of the sample was measured by a multiwavelength separation analyzer (LUMIReader®, https://www.lum-gmbh.com/lumireader_en.html). This device measures space and time resolved profiles of the transmitted light across the water-diluted sample (5% solid content) during sedimentation of particles. The cumulative volume-weighted particle size distribution is obtained from the extinction profiles using the multi-wavelength Particle size Analyser modulus (PSA). Details on the sample preparation procedure can be found in Detloff et al. (2006). For each measurement performed (see Table 1), a pdf file and a excel file are provided. The pdf file lists the analysis summary, including a description of the analysis settings and conditions, materials used, and distribution model adopted for the fit. It also provides graphs of the obtained volume weighted cumulative grain size distribution, and of the measured transmission profiles for each wavelength (870 nm, 630 nm and 470 nm, respectively). The Excel (*.xlsx format) file include 4 datasheets, listing the results (sheet name ending *_R) and the fit data (sheet names ending *_F01,*_F02, *_F03) obtained for the different instrument wavelength. In each datasheet the following data are listed in the columns: particle grain size (x3 in µm), volume weighted distribution (Q3(x) in %), Martin diameter (x3m in µm), volume weighted density distribution (q3(x) in 1/µm). The fit datasheets also include information on the fit such as distribution model used and distribution parameters (quantiles, median, standard deviation, span, etc..). A full list of the files included is given in List_of_files_DelBello et al 2017.pdf.
Measurement name Sample type Size class (µm)* Ppamag32_01 Phonolite (Ppa) 32-63 Ppamag32_03 Phonolite (Ppa) 32-63 Ppamag32_61 Phonolite (Ppa) 32-63Ppamag64_01 Phonolite (Ppa) 63-90Ppamin32_00 Phonolite (Ppa) <32 Ppamin32_02 Phonolite (Ppa) <32 Ppamin32_35 Phonolite (Ppa) <32 Ppamix32_02 Phonolite (Ppa) <32 + 32-63 (1:1) Ppamix32_03 Phonolite (Ppa) <32 + 32-63 (1:10)Ppamix32_04 Phonolite (Ppa) <32 + 32-63 (1:5) Ppamix32_05 Phonolite (Ppa) <32 + 32-63 (1:2) Ppamix32_06 Phonolite (Ppa) <32 + 32-63 (1:1) Ppamix32_70 Phonolite (Ppa) <32 + 32-63 (1:10) Ppamix32_71 Phonolite (Ppa) <32 + 32-63 (1:5) Ppamix32_72 Phonolite (Ppa) <32 + 32-63 (1:2) Ppamix32_73 Phonolite (Ppa) <32 + 32-63 (1:1) Ppamix63_02 Phonolite (Ppa) <32 + 63-90 (1:1) Ppatotal_01 Phonolite (Ppa) total Sakmag32_02 Andesite (Sak) 32-63 Sakmag63_01 Andesite (Sak) 32-63 Sakmag90_01 Andesite (Sak) 63-90 Sakmin32_01 Andesite (Sak) <32 Sakmin32_02 Andesite (Sak) <32 Saktotal_01 Andesite (Sak) total Table 1. List of particle size characterization measurements included in this dataset. *When mixed sample are used, the respective weight proportion of the component classes used are reported in brackets.
# 2
Brunke, Heinz-Peter • Widmer-Schidrig, Rudolf • Korte, Monika
Abstract: For frequencies above 30 mHz the instrument intrinsic noise level of typical fluxgate magnetometers used at geomagnetic observatories usually masks ambient magnetic field variations on magnetically quiet days. Natural field variations referred to as pulsations (Pc-1, Pc-2, Pi-1) fall in this band. Usually their intensity is so small that they rarely surpass the instrumental noise of fluxgate magnetometers. INTERMAGNET has set a minimum quality standard for definitive 1 s data (Turbitt, 2014) which can actually hardly be met by fluxgate magnetometers in use by magnetic observatories. Brunke et al. (2017) propose a method to improve 1Hz observatory data by merging data from the proven and tested fluxgate magnetometers currently in use with induction coil magnetometers into a single data stream. This data publication includes the according MATLAB software package implementing the merging of both data sets. The content of the software package and the functionality of each module is described in the content.txt file that is also included in the zip folder. The resulting data are in line with the INTERMAGNET format for 1 s magnetic data, but surpasses the INTERMAGNET 1 s standard by far. The long term stability of the fluxgate data is not affected. The changes to the fluxgate data remain within the range of the instrument intrinsic noise. In addition to the Matlab software, we provide test datasets of one day length kindly provided by the magnetic observatories Niemegk, Conrad and Eskdalemuir.
# 3
Hunfeld, Luuk • Niemeijer, André • Spiers, Christopher
Abstract: We investigated the frictional properties of simulated fault gouges derived from the main lithologies present in the seismogenic Groningen gas field (NE Netherlands), employing in-situ P-T conditions and varying pore fluid salinity. Direct shear experiments were performed on gouges prepared from the Carboniferous Shale/Siltstone underburden, the Upper Rotliegend Slochteren Sandstone reservoir, the overlying Ten Boer Claystone, and the Basal Zechstein anhydrite-carbonate caprock, at 100 ºC, 40 MPa effective normal stress, and sliding velocities of 0.1-10 µm/s. As pore fluids, we used pure water, 0.5-6.2 M NaCl solutions, and a 6.9 M mixed chloride brine mimicking the formation water. Our results show a mechanical stratigraphy, with a maximum friction coefficient (µ) of ~0.65 for the Basal Zechstein, a minimum of ~0.37 for the Ten Boer claystone, ~0.6 for the reservoir sandstone, ~0.5 for the Carboniferous, and µ-values between the end-members for mixed gouges. Pore fluid salinity had no effect on frictional strength. Most gouges showed velocity-strengthening behavior, with little effect of pore fluid salinity on (a-b). However, Basal Zechstein gouge showed velocity-weakening at low salinities and/or sliding velocities, as did 50:50 mixtures with sandstone gouges, tested with the 6.9 M reservoir brine. From a Rate-and-State-Friction viewpoint, our results imply that faults incorporating Basal Zechstein anhydrite-carbonate material at the top of the reservoir are the most prone to accelerating slip, i.e. have the highest seismogenic potential. The results are equally relevant to other Dutch Rotliegend fields and to similar sequences globally. The data is provided in a .zip folder with 29 subfolders for 29 experiments/samples. Detailed information about the files in these subfolders as well as information on how the data is processed is given in the explanatory file Hunfeld-et-al-2017-Data-Description.pdf
# 4
Ritter, Malte Christian • Santimano, Tasca • Rosenau, Matthias • Leever, Karen • Oncken, Onno
Abstract: This dataset is supplementary to the article of Ritter et al. (2017). In this article, a new experimental device is presented that facilitates precise measurements of boundary forces and surface deformation at high temporal and spatial resolution. This supplementary dataset contains the measurement data from two experiments carried out in this new experimental device: one experiment of an accretionary critical wedge and one of Riedel-type strike-slip deformation. For a detailed description of the set-up and an analysis of the data, please see Ritter et al. (2017). The data available for either experiment are:• A video showing deformation in top view together with the evolution of boundary force. This file is in AVI-format.• A time-series of 2D vector fields describing the surface deformation. These vector fields were obtained from top-view video images of the respective experiment by means of digital image correlation (DIC). Each vector field is contained in a separate file; the files are consecutively numbered. The vector fields are stored in *.mat-files that can be opened using e.g. the software Matlab or the freely available GNU Octave. They take the form of Matlab structure arrays and are compatible to the PIVmat-toolbox by Moisy (2016) that is freely available. The most important fields of the structure are: x and y, that are vectors spanning a coordinate system, and vx and vy, which are arrays containing the actual vector components in x- and y-direction, respectively.• A file containing the measurements of the boundary force applied to drive deformation. This file is also a *.mat-file, containing a structure F with fields force, velocity and position. These fields are vectors describing the force applied by the indenter, the indenter velocity and the indenter position
# 5
Quinteros, Javier
Abstract: This service provides routing information for distributed data centres, in the case where multiple different seismic data centres offer access to data and products using compatible types of services. Examples of the data and product objects are seismic timeseries waveforms, station inventory, or quality parameters from the waveforms. The European Integrated Data Archive (EIDA) is an example of a set of distributed data centres (the EIDA „nodes“). EIDA have offered Arclink and Seedlink services for many years, and now offers FDSN web services, for accessing their holdings. In keeping with the distributed nature of EIDA, these services could run at different nodes or elsewhere; even on computers from normal users. Depending on the type of service, these may only provide information about a reduced subset of all the available waveforms. To be effective, the Routing Service must know the locations of all services integrated into a system and serve this information in order to help the development of smart clients and/or services at a higher level, which can offer the user an integrated view of the entire system (EIDA), hiding the complexity of its internal structure. The service is intended to be open and able to be queried by anyone without the need of credentials or authentication.
# 6
Trippetta, Fabio • Carpenter, Brett M • Mollo, Silvio • Scuderi, Marco M. • Scarlato, Piergiorgio • (et. al.)
Abstract: Here we report the raw data of the physical properties of carbonate samples collected along the Monte Maggio normal Fault (MMF), a regional structure (length ~10 km and displacement ~500 m) located within the active system of the Apennines (Italy). In particular, we report results coming from large cores (100 mm in diameter and up to 20 cm long) drilled perpendicular to the fault plane made of Calcare Massiccio (massive limestone) and Bugarone fm (limestone with 8.3 % of clay). From these large cores, we obtained smaller cores, 38 mm in diameter both parallel and perpendicular to the fault plane, that have been used for experiments. We have divided the rock samples in four categories following the fault architecture. The four structural domains of the fault are:1) the hangingwall (HW) made of Bugarone fm that is still preserved in some portions of the fault, 2) a Cemented Cataclasite (CC) and 3) a Fault Breccia (FB) that characterize the cataclastic damage zones and 4) the correspondent undeformed protolith of the footwall block made of Calcare Massiccio. Raw data reported here are those used for drawing Figures 5, 6, 8 and 9 of the paper “Physical and transport property variations within carbonate- bearing fault zones: Insights from the Monte Maggio Fault (central Italy)”, http://doi.org/10.1002/ 2017GC007097 by Trippetta et al. Dataset_Fig05.txt reports P- and S-wave velocities (in km/s) of the described samples at pressure from 0.1 MPa (ambient pressure) up to 100 MPa at ambient temperature in dry conditions and the corresponding Vp/Vs ratio. Experiments have been performed by using the permeameter at the HP-HT Laboratory of experimental Volcanology and Geophysics at INGV (Rome). Dataset_Fig06.txt reports permeability data (in m^2) on the same type of samples of fig05 for the same range of confining pressure at ambient temperature. Pore pressure values athletes each confining pressure step are indicated in the file. Data have been again acquired with the permeameter. Dataset_Fig08.txt reports P-wave velocity data (in km/s) vs depth (in m), recorded on the portion that crossed the Calare Massiccio fm of three boreholes drilled in the Apennines: Varoni 1, Monte Civitello 1 and Daniel1. Data have been obtained by digitalizing each pdf file of the boreholes mentioned above, that are available at http://unmig.sviluppoeconomico.gov.it/videpi/videpi.asp. Once digitalized, respect to the original pdf file, velocity data have been simply converted from um/f to km/s. Dataset_Fig09.txt reports values of the maximum, minimum and average values of Critical fault nucleation length (in m) at each corresponding depth (in m) and applied confining pressure (in MPa). Critical nucleation lengths have been calculated by using the equations described in the text of the Trippetta et al paper and by using the elastic parameters calculated from data reported here. Data on earthquakes-depth distribution of the 2009 L'Aquila sequence can be found on Chiaraluce et al. (2011).
# 7
van den Ende, Martijn
Abstract: Intergranular pressure solution creep is an important deformation mechanism in the Earth’s crust. The phenomenon has been frequently studied and several analytical models have been proposed that describe its constitutive behavior. These models require assumptions regarding the geometry of the aggregate and the grain size distribution in order to solve for the contact stresses, and often neglect shear tractions. Furthermore, analytical models tend to overestimate experimental compaction rates at low porosities, an observation for which the underlying mechanisms remain to be elucidated. Here we present a conceptually simple, 3D Discrete Element Method (DEM) approach for simulating intergranular pressure solution creep that explicitly models individual grains, relaxing many of the assumptions that are required by analytical models. The DEM model is validated against experiments by direct comparison of macroscopic sample compaction rates. Furthermore, the sensitivity of the overall DEM compaction rate to the grain size and applied stress is tested. The effects of the interparticle friction and of a distributed grain size on macroscopic strain rates are subsequently investigated. Overall, we find that the DEM model is capable of reproducing realistic compaction behavior, and that the strain rates produced by the model are in good agreement with uniaxial compaction experiments. Characteristic features, such as the dependence of the strain rate on grain size and applied stress, as predicted by analytical models, are also observed in the simulations. DEM results show that interparticle friction and a distributed grain size affect the compaction rates by less than half an order of magnitude. The zip-file Van-den-Ende_2017.018.zip contains several folders with raw data from the laboratory experiments, output data from Discrete Element Method simulations, and Python 2.7 script files that read and process these data. All data are stored in ASCII format.
# 8
Wu, Hu • Müller, Jürgen • Brieden, Phillip
Abstract: IfE_GOCE05s is a GOCE-only global gravity field model, which was developed at the Institut für Erdmessung (IfE), Leibniz Universität Hannover, Germany. The observations with a time span from 1 November 2009 to 20 October 2013 are used for the model recovery. The GOCE precise kinematic orbit with 1-s sampling rate is processed for the gravity field up to degree/order 150, while the three main diagonal gravity gradients are down-sampled to 2 s and used to recover the model up to degree/order 250. With two additional Kaula’s regularizations, the combined model “IfE_GOCE05s” is derived, with a maximum degree of 250. To develop IfE_GOCE05s, the following GOCE data (01.11.2009 - 20.10.2013) was used: * Orbits: SST_PKI_2, SST_IAQ_2; * Gradients: EGG_GGT_2, EGG_IAQ_2. None any priori gravity field information was used.
Processing procedures: Gravity from orbits (SST): * Acceleration approach was applied to the kinematic orbit data; * PKI data was at 1 s sampling rate; * Model was derived up to d/o (degree/order) 150; * VCM (Variance-Covariance Matrix) was derived arc-wisely from the post-fit residuals. Gravity from gradients (SGG): * Gradients Vxx, Vyy and Vzz in the GRF (Gradiometer Reference Frame) were used; * Gradients were down-sampled to 2 s; * Model was derived up to d/o 250; * VCM was estimated arc-wisely from the post-fit residuals. Regularization: * A strong Kaula-regularization was applied to constrain the (near-)zonal coefficients that are degraded by the polar gap problem; * A slight Kaula-regularization was applied to improve the signal-to-noise ratio of the coefficients between d/o 201 and 250; * The regularization parameters were empirically determined. Combined solution: * The normal equations for SST and SGG were summed wih proper weighting factors; * Weighting factors for SST and SGG were determined from variance component estimation; * A direct inversion was applied on the final normal equation.
# 9
Lu, Biao • Barthelmes, Franz • Petrovic, Svetozar • Pflug, Hartmut • Förste, Christoph • (et. al.)
Abstract: The dataset contains the results of airborne gravimetry realized by the GEOHALO flight mission over Italy in 2012. The intention was to show whether and how an efficient airborne gravity field determination is feasible in wide areas when using a fast jet aircraft like HALO at higher altitudes. Here, unlike in airborne gravimetry for exploration purposes, the aim is not primarily to reach the highest spatial resolution by flying as low and slowly as possible. A challenge for HALO would be to map areas (e.g., Antarctica) where only insufficient or no terrestrial gravity data are available to achieve a resolution which is better than that of satellite-only gravity field models. This is beneficial for the generation of global gravity field models which require a uniform, high spatial resolution for the gravity data over the entire Earth. The raw gravimetry recordings were recorded by the GFZ air-marine gravimeter Chekan-AM. Kinematic vertical accelerations were calculated from Doppler observations which were derived by GNSS carrier phase measurements (1 Hz). To remove the high-frequency noise, a low-pass filter with a cut-off wavelength of 200 s (corresponding to a half-wavelength resolution of approximately 12 km) was applied to both the Chekan-AM measurements and GNSS kinematic accelerations. To investigate how future airborne gravity campaigns using jet aircraft could be optimized, a dedicated flight track was repeated two times which shows that the equipment worked well also at higher altitude and speed. For the accuracy analysis 17 crossover points could be used. This analysis yielded a RMS of the gravity differences of 1.4 mGal which, according to the law of error propagation, implies an accuracy of a single measurement to be 1 mGal. The dataset is provided in as ASCII text (Lu-et-al_2017-001_Tracks_GEOHALO.txt) and is described in the README. For a detailed description of the set-up and analysis of the data, please see Biao et al. (2017, http://doi.org/10.1002/2017JB014425).
# 10
Bernd Schurr • Anke Dannowski • Branislav Glavatovic • Llambro Duni • Heidrun Kopp • (et. al.)
Abstract: Raw-, SEG-Y and other supplementary data of the landside deployment from the amphibious wide-angle seismic experiment ALPHA are presented. The aim of this project was to reveal the crustal and lithospheric structure of the subducting Adriatic plate and the external accretionary wedge in the southern Dinarides. Airgun shots from the RV Meteor were recorded along two profiles across Montenegro and northern Albania.
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