Lauritsen, Nynne Louise Berthou

Et magnetotellurisk feltarbejde er blevet udført i Nordvest Grønland, med formålet at undersøge geologien i undergrunden. Resultatet fra to forskellige databehandlingsteknikkerer præsenteret, en enkelt stations robust databehandling og en fler stationsdatabehandlingsteknik. Fler stations databehandlingsteknikken forsøger at fjerne data,som indeholder signal fra andre kilder end dem, som stammer fra den plane bølge ved at fjerne ikke korreleret støj mellem stationer og udvælge tidsperioder vha. et egenværdikriterium. Teknikken virker for perioder mindre end 55 s, men skal undergå videreundersøgelser for længere perioder. De to teknikker viser tilsvarende resultater, men flerstations teknikken forbedrer data kvaliteten omkring 1 s sammenlignet med enkeltstations teknikken. Forskellige udfordringer er forbundet med feltarbejdets placering iGrønland, hvor havet og fjordene har en stor indflydelse på overførselsfunktionerne. Et3D model studium er præsenteret, som viser fjordenes påvirkning af induktion vektorerne. Resultatet viser vigtigheden af at inkludere fjorde i magnetotellurisk modellering.Denne information er inkluderet i 3D modelleringen af det magnetotelluriske feltarbejde i Grønland, sammen med dybdemålingen af havet. Modelleringen viser, at påvirkningen fra fjordene og havet dominerer signalet, hvilket gør det problematisk at adskille dette signal fra signalet, der stammer fra geologien i undergrunden.A magnetotelluric survey has been conducted in North West Greenland, with the purpose of investigating the subsurface. The results of two processing techniques are presented, a single station robust processing and a multiple station processing. The multiple station processing tries to eliminate data originating from other sources than the plane wave by removing incoherent noise between stations and selecting time periods from an eigenvalue criteria. It is successful for periods below 55 s, but has to undergo further investigation at longer periods. The two processing techniques show similar results, however the multiple station technique improves the data quality around 1 s compared to the single station technique. Different challenges are connected with the survey location, where ocean and fjord systems have a large impact on the transferfunctions. A 3D model study of the impact of fjords on induction arrows is presented, illustrating the importance of including these in magnetotelluric modelling. This informationis included in the 3D modelling of the magnetotelluric survey in Greenland, together with the bathymetry of the ocean. The modelling shows that the impact from the fjords and ocean heavily dominates the signal, making it difficult to differentiate any geology in the subsurface

Online Research Database In Technology

Magnetotelluric investigation in West Greenland - considering the polar electrojet, ocean and fjords

http://orbit.dtu.dk/ws/files/128332827/Rapport_NLauritsen.pdf

Magnetotelluric investigation in West Greenland - considering the polar electrojet, ocean and fjords

Abstract

Similar works

Full text

Available Versions

Online Research Database In Technology