the seismic spectrum

The Seismic Spectrum

The Seismic Spectrum

Jonathan Berger

Institute of Geophysics and Planetary PhysicsScripps Institution of OceanographyUniversity of California San Diego

Jonathan Berger

Institute of Geophysics and Planetary PhysicsScripps Institution of OceanographyUniversity of California San Diego

Earthscope - Permanent Array

Model STS-1 KS36000I KS5400

Type Force Feedback Force Feedback Force Feedback

Geometry 1-component3-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 Triaxial3-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 ±9.2e-2 ms-1

Full Scale (Acc) ±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

Full Scale (Vel)

Full Scale (Acc) ±10 ms-2 ±10 ms-2

GSN “Strong-Motion” Sensors

KS54000 ready to go down WRAB Borehole

STS1 with bell jar

CMG-3T STS-2

ParoscientificMicro-barometer

FBA23

EpiSensor

The GSN Station RAYNSolar 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 Analysis118 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 secAmplitudes: 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

NormalModes

180 dB

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