The Seismic Spectrum
Jonathan Berger
Institute of Geophysics and Planetary Physics
Scripps Institution of Oceanography
University of California San Diego
Earthscope - Permanent Array
Model
STS-1
KS36000I
KS5400
Type
Force Feedback
Force Feedback
Force Feedback
Geometry
1-component
3-component (ortho)
3-component (ortho)
Orientation
accuracy
±2˚ (with care)
±3˚
±3˚
Output
velocity
velocity
velocity
Sensitivity
±1200 v/ms-1
±1200 v/ms-1
±1200 v/ms-1
Bandwidth
360 sec - 5 Hz
360 sec - 4.2 Hz
330 sec - 4.2 Hz
Full Scale (V)
±20 V differential
±20 V differential
±20 V differential
Full Scale (Vel)
±8e-3 ms-1
±1.2e-2 ms-1
±1.2e-2 ms-1
Full Scale (Acc)
±2.5e-3 ms-2
±1.9e-2 ms-2
±1.9e-2ms-2
GSN “Long-Period” Sensors
Model
STS-2
CMG-3T
GS-13
Type
Force Feedback
Force Feedback
Moving Coil
Geometry
Triaxial
3-component (ortho)
3-component (ortho)
Orientation
accuracy
±0.3˚ at 6 sec
±3˚
±2˚ (with care)
Output
velocity
velocity
velocity
Sensitivity
±750 v/ms-1
±1200 v/ms-1
±1090 v/ms-1
Bandwidth
120 sec - 50 Hz
100 sec - 50 Hz
10 Hz (Brick Amp)
Full Scale (V)
±20 V differential
±20 V differential
±20 V differential
Full Scale (Vel)
±1.3e-2 ms-1
Full Scale (Acc)
±9.2e-2 ms-1
±2e-2 ms-2
GSN “Short-Period” Sensors
Model
FBA-23
Episensor
Type
FBA
FBA
Geometry
Triaxial
Triaxial
Orientation
accuracy
±3˚ (with care)
±3˚ (with care)
Output
Acceleration
Acceleration
Sensitivity
±0.25 v/ms-2
±2 v/ms-2
Bandwidth
50 Hz
50 Hz
Full Scale (V)
±2.5 V differential
±20 V differential
±10 ms-2
±10 ms-2
Full Scale (Vel)
Full Scale (Acc)
GSN “Strong-Motion” Sensors
STS1 with bell jar
KS54000 ready to go
down WRAB Borehole
CMG-3T
STS-2
Paroscientific
Micro-barometer
FBA23
EpiSensor
The GSN Station RAYN
Solar powered, Borehole Seismometer
The GSN Station AAK
The tunnel entrance
The GSN Station AAK
One of the vaults
DGAR - Vault under construction
DGAR - The finished product
DGAR - Inside the Vault
GSN Noise Analysis
118 GSN Stations of the IU and II
networks for the year July 2001 through
June 2002.
Each station-channel data segmented
into hourly, 1 to 11 hour segments.
noise estimated in 50% overlapping 1/7
decade (∂f/f=0.33, ~1/2 octave) bands.
Normal Modes
Sources: ~ 20˚
Period: 0.5 to 10 x 10-3 Hz
Amplitudes: to ~10-5 ms-2
Teleseismic Signals
Sources: >~ 3000 km
Period: 3600 sec to several sec
Amplitudes: to ~10-3 ms-2
Regional Signals
Sources: >~ 100 km
Bandwidth: ~30 sec to 10 Hz
Amplitudes: to ~10 -1 Ms-2
Local Signals
Sources: <~10 km
Bandwidth: several seconds to ~30 Hz
Amplitudes: to ~10 ms-2
Normal
Modes
180 dB
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