Erebus putative seismic tremor infrasound observed at i55us on day 260 2002 sep 17
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Erebus Putative Seismic-Tremor Infrasound observed at I55US on day 260, 2002, Sep.17. Charles R. Wilson, John V. Olson and Daniel L. Osborne, Geophysical Institute, University of Alaska at Fairbanks, Alaska October 17, 2003. Eight sensor array at I55US with Erebus volcano.

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Erebus putative seismic tremor infrasound observed at i55us on day 260 2002 sep 17

Erebus Putative Seismic-Tremor Infrasound observed at I55US on day 260, 2002, Sep.17

Charles R. Wilson, John V. Olson and Daniel L. Osborne, Geophysical Institute, University of Alaska at Fairbanks, Alaska

October 17, 2003



Erebus seismic tremor infrasound 9 17 02
Erebus seismic tremor infrasound 9/17/02 on day 260, 2002, Sep.17

Trace Velocity

0.339 Km/sec

Azimuth

339 deg.

Maximum peak-

To-peak Amp

0.02 Pascal


Abs fft tremor infrasound 05 05 to 05 05 30 260
Abs(fft) tremor infrasound 05:05 to 05:05:30, 260 on day 260, 2002, Sep.17

0.86 sec


Erebus tremor infrasound 9 17 02 05 05 30 05 06 00 ut
Erebus Tremor Infrasound 9/17/02, on day 260, 2002, Sep.1705:05:30-05:06:00 UT

Velocity

0.308 km/sec

Azimuth

341 deg.


Abs fft tremor infrasound 12 25 to 12 26 ut day 260
Abs(fft) tremor infrasound 12:25 to 12:26 UT day 260 on day 260, 2002, Sep.17

0.89 sec


Abs fft erebus infrasound 13 05 to 13 06 day 260
abs(fft) Erebus infrasound 13:05 to 13:06, day 260 on day 260, 2002, Sep.17

1.08 sec


Mccm detector plot erebus infrasound sept 17 2002 12 00 to 13 00 ut
MCCM detector plot Erebus infrasound on day 260, 2002, Sep.17Sept 17,2002 12:00 to 13:00 UT

MCCM

Trace Velocity

340 deg.

Azimuth


Mccm detector plot for random noise on all eight sensors at i55us
MCCM detector plot for random noise on all eight sensors at I55US

Random Noise

Sensor Number 1

MCCM value; 0 to 1

Trace Velocity

Azimuth of arrival

One hour of time


Phase aligned overlay inner three sensors of tremor infrasound day 260 04 01 to 04 10 ut
Phase-aligned overlay inner three sensors of I55UStremor infrasound day 260, 04:01 to 04:10 UT


Uncertainty in velocity and azimuth for tremor infrasound day 260 04 01 to 04 10
Uncertainty in velocity and azimuth for I55UStremor infrasound day 260, 04:01 to 04:10

Velocity = 307 m/sec +/- 1.35 m/sec

Azimuth = 340 +/- 0.25 deg



Mccm detector plot i55us 9 17 02 filtered data 0 7 to 10 hz inner sensors only
MCCM Detector plot, I55US, 9/17/02 for tremor inf. Day 260filtered data (0.7 to 10 Hz) inner sensors only

MCCM

Velocity

340 deg.

Azimuth


Azimuth of arrival for 24 hours 9 17 02 i53us
Azimuth of Arrival for 24 hours 9/17/02 I53US for tremor inf. Day 260

340 deg.


Trace velocity i53us 09 17 02
Trace Velocity I53US 09/17/02 for tremor inf. Day 260

0.350 km/s

0.30 km/s



Mccm plot i55us 6 03 03 filtered 0 70 to 10 hz
MCCM plot I55US 6/03/03 filtered (0.70 to 10 Hz) for tremor inf. Day 260

340 deg.




Co ntinuous type erebus tremor signals
Co for tremor inf. Day 260ntinuous-Type Erebus “tremor” signals

  • During the year 2002 four episodes have been found in the I55US data set of very low amplitude, continuous-type infrasound from an average azimuth of 340 +/- 0.78 deg, with an average trace velocity of 329.50 +/- 3.0 m/sec

  • The average amplitude of these signals is 0.01 Pa, with a duration up to 5 hours


Impulsive signals from strombolian type eruptions from the lava lake in the erebus crater
Impulsive Signals from Strombolian-type eruptions from the lava lake in the Erebus Crater

Phase-aligned overlay of 8 sensor traces


Erebus crater with lava lake eruption
Erebus Crater with lava lake eruption lava lake in the Erebus Crater


Strombolian type erebus signal 8 13 2002
Strombolian type Erebus signal 8/13/2002 lava lake in the Erebus Crater

Seconds


Statistics of impulsive signals
Statistics of impulsive signals lava lake in the Erebus Crater

  • 182 Erebus signals received at I55US

  • Period April 2002 to March 2003

  • Average trace vel = 320.5 +/- 6.32 m/sec

  • Average Azimuth = 336.5 +/- 0.39 deg

  • The impulsive signals were filtered in the passband 0.70 to 10 Hz to eliminate the microbarom background

  • Impulsive signals are coherent over the entire 8 sensor array of aperture 1.9 km.


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