The magnetic field data, which were collected from two sensors, were first screened for electronic spikes and corrected for the diurnal variation of the magnetic field, using refer- ence data from base station magnetometers positioned in the survey area. Tellus data were subject to filtering to remove man-made magnetic noise (Lahti et al., 2007). Tellus Border data were subject to a height correction to allow for significant varying survey height, par- ticularly in areas where the vertical gradient and magnetic intensity were high. Levelling of the two surveys was accomplished by different processes; the Tellus data were levelled by a statistical process (White and Beamish, 2015) while the Tellus Border data were levelled by the conventional process that minimises the differences between measurements at the intersections of survey lines and orthogonal ‘tie-lines’.
As shown by our test study, airbornegeophysicalsurveys, especially due to their relatively low resolution in contrary to the ground-based geophysical methods, bring rather infor- mation on the bedrock properties of broader areas than on the landslides’ internal structures themselves. AEM data re- veal the clay content and water saturation in depth, whereas gamma ray indicated especially the clay content near the ground surface (Thorium and Potassium), or indicate mate- rial removal after 1986 ( 137 Cs). However, in the case of such small areas such as the Stože test site, the airborne geophys- ical data have some interpretational constraints. The integra- tion of the results measured on the landslide body into the geophysical signature of the background of the surrounding area is very difficult. Therefore, proper and detailed com- paring the results to other geological and geomorphic data
2014). As noted by Keisling et al. (2014), the layer continu- ity index is uniformly high in this region except in the ice stream shear margins, with numerous bright internal layers traceable for several hundred kilometres through the central portion of the ice sheet, allowing confident layer tracing. In- ternal layers were identified in and propagated through RES profiles using a semi-automatic algorithm that identifies the peak of the radar wavelet nearest an initial user-identified peak, then automatically selects the flanking changes in con- cavity, and finally follows this wavelet along a radar profile. As occasional user interaction is required, two independent interpreters informed the layer-tracing algorithm to elimi- nate user bias. We were able to identify 27 internal layers at NGRIP; 14 of these layers were continuous in airborne RES profiles between NGRIP and NEGIS (Keisling et al., 2014). Although the deepest continuous layer traceable from NGRIP to NEGIS is only ∼ 51 kyr, there is ∼ 600 m of ad- ditional ice present at NEGIS with many additional coherent internal layers present (Fig. 6; Keisling et al., 2014). Thus, the ice here is likely to be considerably older than ∼ 51 kyr. Although the uncertainty in this layer-tracing approach is sig- nificant, and increases with depth due to increasing uncer- tainty in both layer age and depth calculations, the uncer- tainty in the deepest layers is on the order of only a few thou- sand years. Internal layers in the deepest ice (0–300 m above the bed) are blurry, and although there are traceable packets of energy, clear radar wavelets similar to a Ricker wavelet are not present. It is possible that stratigraphy in this deepest ice has been disturbed due to ice folding and overturning in a similar manner to ice in the deepest sections of the NEEM ice core (NEEM Community members, 2013).
So far hardly any case studies are published concerning gamma ray surveys on landslides. However, since the respec- tive nuclides can be found in different rocks and soils at var- ious concentrations, the results from this study suggest that the spatial distribution of these elements and/or their ratio can provide information about soil parent material and soil and rock properties, such as composition, weathering, leach- ing clay types and others. This information could be used to determine areas with a higher susceptibility to sliding. An- other interesting aspect is the mapping of 137 Cs distribution. Active landslide areas show lower 137 Cs activity due to sur- face water flows, increased soil erosion and covering of the topmost layer that lead to the migration of the nuclides.
Validation of results was undertaken through field observations, global positioning sys- tem (GPS) readings, collection of samples for thin section studies and XRD analysis (to determine the concentrations of clay minerals). The spectra of representative samples from hydrothermal alteration zones were measured using a Field Spec3® spectroradi- ometer. Spectral analysis was carried out for mineral recognition based on reference spectra from the USGS digital spectral library . The methodology is schematically presented in Figure 5.
The advance of the airbornegeophysical data processing techno- logies and the integration with geological data allow to recover useful and valuable information from geophysicalsurveys carried out with older techniques. This information (rock types, structu- res) represents an essential tool to conventional geologic map- ping and characterization of the tectonic evolution of Precambrian terrains, where the stratigraphic and structural relations are usu- ally obliterated by later deformational events or hidden by uncon- solidated sediments.
Nine (9) high-resolution of aeromagnetic and radiometric data of the Benue Trough and adjacent Anambra Basin, were evaluated to understand the subsurface geological structure of the area. Various data enhancement/derivative techniques like analytic signal, first and second vertical derivatives, horizontal derivative and tilt derivative were employed in delineating magnetic lineaments, edges, lithological boundaries, and contact zones within the area. The results obtained revealed magnetic lineaments, shear zones and shallow faults, trending mostly in NE-SW, E-W, and NW-SE directions. The ternary image generated from Radiometric data using oasis Montaj software highlights the lithology of Asu River Group, Eze-Aku Formation, Agwu Shale, Nkporo Shale, Nsukka Formation and Ajali Sandstone. This shows an improved version of the geological mapping of the study area
provinces in Brazil, but lack geological studies at an appropriate scale in its southeastern portion. Fieldwork, petrography, and high-resolution airborne geophysics (magnetometry and gamma spectrometry) allowed us to produce a new map at the 1:100,000 scale. In this study, we identified two new geological units: (1) the volcanic and pyroclastic rocks of the Vila Riozinho Formation, previously attributed to the Iriri Group, including a newly described facies of this formation, which comprises a group of rocks with the highest magnetic contents of the study area, and (2) the Serra Alkali Feldspar Granite, which intruded into the Vila Riozinho Formation. Based on available geochronological information these units can be associated to a volcano-plutonic event that occurred in the Orosirian period, at about 1.98 Ga. In addition, our work allowed us to define better the areas of occurrence of other units. The Parauari Intrusive Suite and Iriri Group areas were strongly reduced, whereas the areas of the Creporizão Intrusive Suite and of the Novo Progresso Formation were increased.
Technique: Airborne Scanning Lidar Altimeter. It is common practice in airborne lidar surveys to use GNSS both to position the instrument very precisely, and to assist an inertial navigation system (INS) to obtain the orientation of the aircraft in space; as both position and orientation are needed to interpret the data properly. Figure 1 illustrates the relationship between the sensors used for airborne lidar surveys. The aircraft utilizes a GNSS antenna combined with an INS to “georeference” its trajectory. The bore-sight calibration process aligns the individual sensor orientations and standardizes the range measurements. However, if the survey is to achieve the now expected high level of vertical accuracy (±15 cm, 1 sigma), then the position of the GNSS/INS-derived aircraft trajectory for each laser swath must be determined with a relative precision in the order of just a few centimeters. This is achieved via differential GNSS post- processing of the kinematic airborne data together with static observations collected on precisely surveyed ground reference stations. The GNSS positions are then blended with high-frequency measurements taken by the onboard INS to produce the final trajectory and reference orientations.
In total there were 413 responses to the survey. The majority of responses (65%) were from parents of school children, although 26% of responses (108 in total) were from secondary school children themselves – This is a good response rate which gives validity to the results for both groups. The full breakdown of response by respondent type was as follows:
The project brief was to develop a pilot study to help “establish new and untested approaches” to making information accessible to citizens in the light of advances in data visualization and to “push out the boat” in terms of the approaches used in so-doing (CLG 2008). As the term ‘citizens’ refers to a large and diverse group of individuals in terms of access to web technology, technical ability and interest, it was important for our design to accommodate some of this diversity, supporting both the casual browser and the citizen with a more in-depth interest in the results, whilst employing novel ap- proaches to information presentation and access. We established high-level requirements using a visualisation awareness session (Koh et al. 2011), followed by a combination of brainstorming and structured exercises as described by Dykes et al. (2010). These in- cluded a discussion and prioritisation of needs, forms of innovation that could be used and a post-workshop exercise in which LCC participants were asked to develop user sto- ries based upon their areas of expertise, to enable us to ground the development of the application in valid use cases.
Post-processing of the ALS survey flight trajectory data used the PosPac Mobile Mapping Suite (Applanix), with Trimble CenterPoint RTX with vertical and horizontal positional un- certainties that were typically better than ± 15 cm (1σ ). We post-processed point clouds and exported data into LAS (li- dar data exchange file) files, a binary file format that can be efficiently processed with LAStools (https://rapidlasso.com/ lastools/, last access: 30 May 2017, Isenburg, 2014). We used the LAStools las2dem algorithm to create 1 m resolution dig- ital elevation models (DEMs). Las2dem triangulates ground classified ALS points from LAS files into a temporary tri- angulated irregular network (TIN). A DEM is then created from this using nearest-neighbor interpolation. Given an av- erage point density of greater than 2 points m −2 (Table 2), little interpolation was required. We coregistered all DEMs following the method detailed in Nuth and Kääb (2011). For late summer surveys, one master DEM was chosen and all other late summer DEMs were coregistered to that DEM for stable terrain (e.g., off-glacier) only. Stable terrain was iden- tified in satellite imagery and excluded forests, lakes, and ice- and snow-covered areas. For winter DEMs, the previ- ous late summer DEM was used as the master DEM to mit- igate against any surface height changes in areas defined as stable terrain, due to processes such as rockfall or vegeta- tion height change. During the spring surveys, there was little to no snow-free terrain, except rocky features with extreme slopes which are not used in the coregistration (slope > 40 ◦ excluded). We thus did not apply any vertical shift during coregistration of winter DEMs.
ABSTRACT: the composition and ecology of the millipede fauna of Victoria remain poorly understood. We collected millipedes as part of a series of ecological arthropod surveys across south-eastern australia, focusing mainly on Victoria. these samples almost exclusively contained millipedes from the introduced order Julida. We pursued species identification of the julids when it became apparent there were species other than the well-recorded Ommatoiulus moreleti (lucas, 1860) (portuguese millipede) in the samples. the majority of specimens were O. moreleti, but we also detected at least one species of Cylindroiulus Verhoeff, 1894, as well as an Ophyiulus Berlese, 1884, species, specimens of which have been identified as Ophyiulus cf. targionii. these are the first Ophyiulus records for Victoria to our knowledge. We present preliminary data on the abundance through the year of Ophyiulus. this is the first study to examine this species in Victoria and little is currently known about its likely impact on agriculture or on native species. Monitoring and research of the species in the future is therefore warranted.
To help nonprofits better understand how their current practices compare to similar organiza- tions and where there are opportunities for improvement, Tate & Tryon is conducting a three-part series on accounting best practices that entails (1) collecting information on the accounting practices of nonprofits and (2) providing survey results with recommendations for improving financial process performance and efficiency.