FJERNANALYSE

Som en del av et fjernanalyseprosjekt innenfor det samarbeidsprogrammet mellom Norges geologiske undersøkelse og det tidligere sovjetiske (nå russiske) vitenskapsakademiet ble det ervervet digitale radardataer (SAR - Synthetic Aperture Radar) fra Varangerhalvøya, Finnmark, generert av en sensor ombord i den europeiske fjernanalysesatelitten ERS-1. I rapporten blir noen få bilder, eller forstørrede delbilder presentert og en sammenligning gjort med det eksisterende berggrunnsgeologiske kartet og med falskfargete kompositte Landsat TM-bilder tatt fra samme områder på Varangerhalvøya.

Remote sensing technology applied to resource monitoring has been carried out in the Engjebø mountain. These tests combines laboratory measurement of the reflectivity, field measurements and spectral data collected with an airborne hyperspectral scanner. Even though the field measurement on the ground indicted that a spectral separation should be possible, the spectral analyses collected by an aircraft with 10m x 10m resolution, do not give any clear detection of the rock-types. This is mostly thought to be caused by the vegetation in the area.

A map of all lineaments resolvable at 1:100,000 scale on a LANDSAT TM5 image utilizing bands 1,2, and 3 was constructed over the Møre Trøndelag region of central Norway. This onshore fracture lineament map was merged with an offshore lineamnet map constructed from 500 meter grid bathymetric data and with maps of potential field data. Analysis of the fracture lineament map resolved a high density region in the north of the study area and a low density region to the south. NW-SE trending fracture lineaments show the greatest variation in density,followed by NE-SW trending lineaments. Densities of N-S and E-W trend- ing lineaments are unaffected by geography. By combining lineament patterns with lineament density grids, topographic and bathymetric data, marine and onshore magnetic and gravity data, field data, and published apatite fission track (AFT) ages we identified three geotectonic blocks. AFT ages within each block are concordant at the 95% confidence level. The AFT ages of the blocks increase from SE to NW and are statistically discrete. Cross sections show that the blocks define a step function topography descending to the NW. Although not precluding strike slip, the data suggest vertical tectonics were important during the Mesozoic and Cenozoic development of the MTFC. Field studies on Vikna Island and the Fosen Peninsula have shown that several lineaments in mid Norway are faults of more than local importance. Steep dip- slip slickenlines on two NE trending fault planes are accompanied by wide damage zones, and a NS trending fault exhibits low angle (strike slip) slicken- lines, extensive brecciation, and cataclasis. On the lineament map, these faults appear as short (<5km) structures forming rhombic intersections with strongly expressed NE-SW lineaments. We interpret these faults to bound small- scale duplex structures within a larger extensional system that ex

Frie emneord: Urban geology ; Subsidence ; Interferometry Timely identification of subsidence is important in order to ensure that remediation efforts are successful. Even if subsidence cannot be prevented or stopped, it must be accounted for in new construction planning. Identification and monitoring of ground deformation can be accomplished using a number of surveying techniques. Levelling and GPS are both expensive and the number of benchmarks that can be controlled is limited. Since the early 1990's satellite-based radar interferometry has been used to identify large ground movements due to earthquakes and volcanic activity. Data stacking methods that take advantage of a growing archive of radar images, as well as increasing computing power, have led to a large increase in the precision of the technique. Both linear trends and seasonal fluctuations can be identified using the Permanent Scatterers technique. In the current project, standard processing was performed on two independent series of radar images covering the Trondheim region. By processing two sets of images, we obtained two independent datasets that could be compared at a regional and local scale. The pattern of subsidence is identical where the datasets overlap. It is proposed that a more detailed processing be carried out over a smaller area of interes. This will result in an increased data density as well as more accurate velocity field. Future monitoring will be possible with the use of images from the Radarset 1 and 2 satellites.

Forkortet.
Timely identification of subsidence is important in order to ensure that remediation efforts are successful. Even if subsidence cannot be prevented or stopped, it must be accounted for in new construction planning. Identification and monitoring of ground deformation can be accomplished using a number of surveying techniques. Levelling and GPS are both expensive and the number of benchmarks that can be controlled is limited.

Keywords: Sediment classification ; Remote sensing ; Seabed sediments ; Software ; Geophysics ; Seafloor topography ; Backscatter ; Multibeam bathymetry ; Acoustic classification
Summary:
Acoustic classification of sediments using single beam and multibeam echo sounders had been under intense development over the past two decades. In the ACOUSEC project, led by Kongsberg-SIMRAD and co-financed by NFR, the goal had been to improve methods and algorithms for acousitc classification, and try to establish acoustic libraries that could minimise the need for ground truthing. NGU had aquired single beem data, evaluated software for multibeam echo sounder classification, and provided sediment samples and sediment maps for calibration of results. Field data have been aquired from the Sula Reef, the Røst Reef Complex, from the TESI area at Møre, from Harstad, Trondheimsfjorden and around Jøa. The evaluation of classification software reveals that backscatter data quality is a critical factor for acoustic classification. This applies both to calibration during data aquisition, and the software used for processing and intepretation. The report concludes that there are important improvements to be done before semi-automatic classification can be performed on the backscatter data, providing a reasonably reliable sediment map.

På oppdrag fra Jernbaneverket Utbygging har NGU utført en oppgradering av det geologiske og geofysiske grunnlagsmaterialet langs planlagt jernbanetrasé Oslo - Ski og framstilt dette i digital form.