Figure 1
(A) Snapshots of an elastic plane wave originated at a remote source at SW, reaching the Earth’s surface with a velocity at an incidence angle . (B) The wavefront traverses the array horizontally with a horizontal velocity at a BAZ . The point 0 is the reference origin for the array, and the position vector to sensor 5, , has an angle with the wave propagation.
Figure 2
Processing flow of beamforming.
Figure 2
Processing flow of beamforming.
Figure 3
Panel A shows the location of the two experiments reported here on a map of Antarctica from the SCAR’s Antarctic Digital Database (https://www.add.scar.org). Panel B shows an aerial view of C-I aligned with the prevailing SN wind. Panel C shows a photo of the Ajax glacier front with a helicopter (circled in red) for the sake of scale. Panel D gives a closer view C-I with its four wind turbines and the AWS on its roof. The responsible for the data collection, Dr. Aquino, is standing in front of the module.
Figure 4
Field layout at 84S, showing the two co-linear gathers, and , running southward from the C-I. The circles are the geophones , laid along a length of . The first geophone is at from C-I baricenter. There is a gap of between geophones of and of .
Figure 5
Spectrogram of geophone 6 of file 4600, showing the energy well distributed over the entire time window and limited to .
Figure 6
Spectral lines from the F-test on geophone 6 of file 4600. Panel A shows the spectral lines for the whole frequency range. Panel B shows spectral lines for . In this figure and all F-Test plots herein, the dashed red line shows the 99% critical threshold.
Figure 7
The multitaper reshaped PSD to the F-test spectral lines of geophone 6 in range .
Figure 8
Panel A shows the trace of geophone 6 with a band-pass of . Panel B shows the difference between the original data and the low-frequency version shown in A.
Figure 9
Panel A gives a depiction of the gather G on Ulmann Point. Panel B gives a map of Martel Inlet with the main landmarks addressed in this work. The location of the gather on Ulmann Point is marked G. E and S are the locations of the EACF Station and the ship position, respectively. Aj, Go, Do and Kr are Ajax, Götel, Dobrowolski, and Krak glaciers.
Figure 10
Spectrogram of geophone 9 of file 503, showing significantly higher amplitudes than at 84S, and repeating time bands of .
Figure 11
Multitaper spectrum of file 503 reshaped to the spectral F-lines with cut-off values . Note the effect of notching the influence of the power inverter at .
Figure 12
Seismogram of wind activity of file 503. The event onsets at each geophone have a conspicuous S-shape due to the relatively lower wind speeds and gather’s 2-D geometry.
Figure 13
Spectrogram of a calving event at geophone 7 of file 1000. Most of the energy lies within the range .
Figure 14
Panel A shows the spectral F-lines of file 1001 with cut-off values , clustering at . Panel B shows the spectral F-lines after band-pass filtering with corners at .
Figure 15
Multitaper spectrum of file 1001 reshaped to the spectral F-lines with cut-off values . Note also the effect of notching the influence of the power inverter at .
Figure 16
A calving event recorded at geophone 7 with a full trace duration. The event onset is at , followed by a detachment or crumbing phase . The fall of the main mass with the water is seen at , followed by some minor activity at .
Figure 17
Spectrogram of geophone 7 of file 1700 showing the ship’s and AC-DC converter’s harmonic lines and their respective multiples.
Figure 18
The PSD of file 1700 shown in the range of . The two peaks are due to the ship’s generator anchored at point S in Figure 9.
Figure 19
Trace of geophone 7 of file 1700. Panel A shows the ship’s signature after band-pass filtering in . Panel B shows the same trace with the ship notched, i.e., without the ship.
Figure 10
Spectrogram of geophone 9 of file 503, showing significantly higher amplitudes than at 84S, and repeating time bands of .
Figure 11
Multitaper spectrum of file 503 reshaped to the spectral F-lines with cut-off values . Note the effect of notching the influence of the power inverter at .
Figure 12
Seismogram of wind activity of file 503. The event onsets at each geophone have a conspicuous S-shape due to the relatively lower wind speeds and gather’s 2-D geometry.
Figure 13
Spectrogram of a calving event at geophone 7 of file 1000. Most of the energy lies within the range .
Figure 14
Panel A shows the spectral F-lines of file 1001 with cut-off values , clustering at . Panel B shows the spectral F-lines after band-pass filtering with corners at .
Figure 15
Multitaper spectrum of file 1001 reshaped to the spectral F-lines with cut-off values . Note also the effect of notching the influence of the power inverter at .
Figure 16
A calving event recorded at geophone 7 with a full trace duration. The event onset is at , followed by a detachment or crumbing phase . The fall of the main mass with the water is seen at , followed by some minor activity at .
Figure 17
Spectrogram of geophone 7 of file 1700 showing the ship’s and AC-DC converter’s harmonic lines and their respective multiples.
Figure 18
The PSD of file 1700 shown in the range of . The two peaks are due to the ship’s generator anchored at point S in Figure 9.
Figure 19
Trace of geophone 7 of file 1700. Panel A shows the ship’s signature after band-pass filtering in . Panel B shows the same trace with the ship notched, i.e., without the ship.
Figure 20
Seismogram of file 1550 for showing a calving event in followed by wind-related events at . Refer to Figure 9 for geophone positions.
Figure 21
Polar plot of event within time window in file 1550. In this and the following polar plots, the BAZ is counted clockwise from N, the slowness is shown along the radial distance, and the color scale corresponds to the relative power.
Figure 22
Seismogram of file 1001 for . Refer to Figure 9 for geophone positions.
Figure 23
Polar plot of event within time window in file 1001.