Databank

Workreport 1997-42

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Name:

Geofysikaaliset lentomittaukset Loviisan alueella v. 1997

Writer:

Jukka Multala; Heikki Hautaniemi

Language:

Finnish

Page count:

30

Summary:

Working report: AEROGEOPHYSICAL SURVEYS IN LOVIISA AREA 1997




ABSTRACT




Geological Survey of Finland did aerogeophysical surveys 25.9 - 26.9.97 in Loviisa/Hästholmen
area. The aerogeophysical methods used were measuring of total intensity of earth’s magnetic
field with Cesium-magnetometer, EM dual frequency (3125,14368 Hz) with dipole source in
vertical coplanar coil configuration,in which coil separation is 21.36 m, and natural gamma
radiation (total radiation,K,Th,U). Primary method was high resolution mapping of earth’s
magnetic total field.


The purpose of this study is to produce more detailed information about bedrock in the survey
area . By means of aerogeophysical surveying the aim is to map different types of granitoids and
create basis for 3-dimensional interpretation. By electromagnetic measurements we can get
information about conductivity and structure of bedrock and further clarify structural
boundaries.

Totally 1084 line kilometers were surveyed, of which 736 km in the main area, 88 km in the
dense main area, and 260 km to measure sparse lines. In the main area line separation was 200
m, in the dense area 100 m, and 1000 m between those sparse lines. The normal flight lines
were measured in N-S direction, and the sparse lines in E-W direction. Nominal flight altitude
was 30 m, and flight velocity 50 m/s, so distance between measuring points was 6 meters in
magnetic, 12 meters in electromagnetic and 50 meters in radiometric measurements.

The measurements were processed to drift and altitude corrected data. The results were
composed to maps , main area in scale 1:20 000, dense area in scale 1:5000, and the sparse lines
in scale 1:50 000. The maps of main and dense area are presented in color maps and the sparse
lines are in profile form. A first vertical derivate was calculated from the magnetic data using
continueing of the field and apparent resistivity from EM data on both frequencies. In the
apparent resistivity maps variation of flight altitude does not effect to the results as it does in
real and imaginary components.


Keywords: geophysics, airborne geophysics,high level nuclear waste disposal
AEROGEOPHYSICAL SURVEYS IN LOVIISA AREA 1997




ABSTRACT




Geological Survey of Finland did aerogeophysical surveys 25.9 - 26.9.97 in Loviisa/Hästholmen
area. The aerogeophysical methods used were measuring of total intensity of earth’s magnetic
field with Cesium-magnetometer, EM dual frequency (3125,14368 Hz) with dipole source in
vertical coplanar coil configuration,in which coil separation is 21.36 m, and natural gamma
radiation (total radiation,K,Th,U). Primary method was high resolution mapping of earth’s
magnetic total field.


The purpose of this study is to produce more detailed information about bedrock in the survey
area . By means of aerogeophysical surveying the aim is to map different types of granitoids and
create basis for 3-dimensional interpretation. By electromagnetic measurements we can get
information about conductivity and structure of bedrock and further clarify structural
boundaries.

Totally 1084 line kilometers were surveyed, of which 736 km in the main area, 88 km in the
dense main area, and 260 km to measure sparse lines. In the main area line separation was 200
m, in the dense area 100 m, and 1000 m between those sparse lines. The normal flight lines
were measured in N-S direction, and the sparse lines in E-W direction. Nominal flight altitude
was 30 m, and flight velocity 50 m/s, so distance between measuring points was 6 meters in
magnetic, 12 meters in electromagnetic and 50 meters in radiometric measurements.

The measurements were processed to drift and altitude corrected data. The results were
composed to maps , main area in scale 1:20 000, dense area in scale 1:5000, and the sparse lines
in scale 1:50 000. The maps of main and dense area are presented in color maps and the sparse
lines are in profile form. A first vertical derivate was calculated from the magnetic data using
continueing of the field and apparent resistivity from EM data on both frequencies. In the
apparent resistivity maps variation of flight altitude does not effect to the results as it does in
real and imaginary components.


Keywords: geophysics, airborne geophysics,high level nuclear waste disposal

Keywords:

geofysiikka; lentomittaukset; aerogeofysiikka; korkea-aktiivisen uraanipolttoaineen loppusijoitus

File(s):

Geofysikaaliset lentomittaukset Loviisan alueella v. 1997 (pdf) (1.3 MB)


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