Active Seismics on Sorsdal Glacier 2015-2016

Full description

The active seismics are all part of a survey of the Sorsdal Glacier. They are designed to measure ice thickness, and the thickness of the water column underneath the ice shelf where the ice is floating. This was part of an investigation to determine the location of the grounding line on Sorsdal Glacier.

Sorsdal Glacier site S04 - 14/12/2015
Timing: 2000 - 2150
Coordinates: S68 42.006, E78 09.439
Team: Sue Cook, James Hamilton, Marty Benavente
Weather: Some high cloud, low wind, good visibility
Site notes: Crevasses greater than 2 m wide running in along flow direction (parallel to geophone cables). Surface very thin layer of icy/hard packed snow with blue ice underneath.
Equipment: Geometrics Geode Seismograph communicating with a laptop via ethernet cable using Geometrics Seismodule Controller Software Version 11.1.69.0 (Geometrics Inc., 2014)
Sampling: 4-second records at 4000 samples/second
Geophones: 40 Hz Blue/yellow geophones used.
Seismic survey layout: 2 x 36 m cables (3 m spacing)
Geophones all set into surface by drilling small hole with handheld drill. Bearing of seismic line: 338 degrees (on compass, no magnetic declination applied)
Geophones 1-12 to East, 13-24 to West
Hammer blows began from East end of line (geophone 1), moving every 6 m towards West end of line. 10 blows at each location.

Sources:
Geophone,File,Hammer swinger
1, 2.dat, JH
3, 3.dat, JH
5, 4.dat, JH
7, 5.dat, JH
9, 6.dat, JH
11, 7.dat, JH
24, 8.dat, MB
22, 9.dat, MB
20, 10.dat, MB
18, 11.dat, MB
16, 12.dat, MB
14, 13.dat, MB
centre, 14.dat, MB

Lineage

Progress Code: completed

Statement: Data are very noisy - thought to be caused by reverberations from nearby crevasses. No thickness measurement could be made, so raw data are all that is available.

Notes

Purpose
Active seismics to measure ice thickness and depth of water column below floating ice.