Sensors

A seismometer is a very sensitive instrument that can detect movements of Earth's surface. The surface is in constant motion due to natural and man-made phenomena. For example, the solid Earth tide is caused by the gravitational pull of the moon stretching Earth. Tucson slowly rises and falls twice a day about 40 cm due to the moon orbiting overhead. Mining explosions are a source of seismic energy. Ambient seismic noise amplitude is measured in nanometers, and can have a frequency bandwidth from 10s of Hz to days. The impulse response of several sensors used by USArray are given in the figure above.

Very-Broadband Seismometer
Broadband Seismometer
Short-Period Seismometer
High-Frequency Seismometer
Strong-Motion Sensor

Back to Instrumentation

Very-Broadband Seismometer

Streckeisen STS-1

Flat to velocity 0.028 - 10 Hz

Dynamic range > 140 dB

Requires extensive vault facilities

3-orthogonal components, 24-bit digitized at 40 Hz

TOP

Broadband Seismometer

Streckeisen STS-2 and Guralp CMG-3T

Flat to velocity 0.01 to 50 Hz

Dynamic range > 140 dB

Requires simple concrete pad with thermal insulation

3-orthogonal components, 24-bit digitized at 40 Hz

Teledyne-Geotech KS54000

Flat to velocity 0.003 - 16 Hz
Dynamic range > 140 dB
Emplaced in 8" borehole, at a depth of 100m
3-orthogonal components, 24-bit digitized at 40 Hz

TOP

Short-Period Seismometer

Guralp CMG 40T-1Hz

Flat to velocity 1s - 100 Hz response

Dynamic range > 90 db

2000 V/m/s sensitivity

Output 20 V peak-to-peak

No mass locking required

Power consumption = 38 Ma at 12 V DC

Weight = 2.49 Kg

Case diameter = 154 mm

Case height = 207 mm

Operating Temperature = -10 to + 75 deg C

Manufacturer link

TOP

High-Frequency Seismometer

Geospace GS11D

Natural Frequency 4.5 Hz

Coil resistance = 380 Ohms

Sensitivity = 0.32 V/cm/sec

Damping with 380 Ohm coil = 762

Moving mass = 23.6 g

Height = 3.35 cm

Diameter = 3.18 cm

Weight = 111 g

Manufacturer link

TOP

Strong-Motion Sensor

Kinemetrics Episensor ES-T

Dynamic Range > 155 Db

Bandwidth DC to 200 Hz

User selectable full-scale range +- 0.25 g, +-0.5 g, =+-1 g, +-2 g, or +-4 g

Power consumption = 35 mA (Low Noise aAmp) @ 12 V DC

Operating Temperature = -20 deg C to 70 deg C

Physical size = 13.3 cm; diameter = 6.2 cm height

Manufacturer link

TOP

HIGHLIGHTS

EarthScope is a partnership extending throughout the Earth science community, including more than 100 universities, the National Science Foundation, US Geological Survey, National Aeronautics and Space Administration, Department of Energy, regional seismic networks and state geological surveys.



			Sensors A seismometer is a very sensitive instrument that can detect movements of Earth's surface. The surface is in constant motion due to natural and man-made phenomena. For example, the solid Earth tide is caused by the gravitational pull of the moon stretching Earth. Tucson slowly rises and falls twice a day about 40 cm due to the moon orbiting overhead. Mining explosions are a source of seismic energy. Ambient seismic noise amplitude is measured in nanometers, and can have a frequency bandwidth from 10s of Hz to days. The impulse response of several sensors used by USArray are given in the figure above. Very-Broadband Seismometer Broadband Seismometer Short-Period Seismometer High-Frequency Seismometer Strong-Motion Sensor Back to Instrumentation Very-Broadband Seismometer Streckeisen STS-1 Flat to velocity 0.028 - 10 Hz Dynamic range > 140 dB Requires extensive vault facilities 3-orthogonal components, 24-bit digitized at 40 Hz TOP Broadband Seismometer Streckeisen STS-2 and Guralp CMG-3T Flat to velocity 0.01 to 50 Hz Dynamic range > 140 dB Requires simple concrete pad with thermal insulation 3-orthogonal components, 24-bit digitized at 40 Hz Teledyne-Geotech KS54000 Flat to velocity 0.003 - 16 Hz Dynamic range > 140 dB Emplaced in 8" borehole, at a depth of 100m 3-orthogonal components, 24-bit digitized at 40 Hz TOP Short-Period Seismometer Guralp CMG 40T-1Hz Flat to velocity 1s - 100 Hz response Dynamic range > 90 db 2000 V/m/s sensitivity Output 20 V peak-to-peak No mass locking required Power consumption = 38 Ma at 12 V DC Weight = 2.49 Kg Case diameter = 154 mm Case height = 207 mm Operating Temperature = -10 to + 75 deg C Manufacturer link TOP High-Frequency Seismometer Geospace GS11D Natural Frequency 4.5 Hz Coil resistance = 380 Ohms Sensitivity = 0.32 V/cm/sec Damping with 380 Ohm coil = 762 Moving mass = 23.6 g Height = 3.35 cm Diameter = 3.18 cm Weight = 111 g Manufacturer link TOP Strong-Motion Sensor Kinemetrics Episensor ES-T Dynamic Range > 155 Db Bandwidth DC to 200 Hz User selectable full-scale range +- 0.25 g, +-0.5 g, =+-1 g, +-2 g, or +-4 g Power consumption = 35 mA (Low Noise aAmp) @ 12 V DC Operating Temperature = -20 deg C to 70 deg C Physical size = 13.3 cm; diameter = 6.2 cm height Manufacturer link TOP				HIGHLIGHTS

			EarthScope is a partnership extending throughout the Earth science community, including more than 100 universities, the National Science Foundation, US Geological Survey, National Aeronautics and Space Administration, Department of Energy, regional seismic networks and state geological surveys.