CMG-3 Seismometers

3TD-side

High performance, low noise, compact, broadband seismometers

The Guralp Systems CMG-3 range of compact three-component broadband sensor are suitable for surface vault, subsurface vault, posthole and borehole installations. The instruments are well proven, established design and have been in continuous production since 1987. The CMG-3T is widely used on many National Seismic Networks, with in excess of 3000 triaxial sensors deployed worldwide.. The instruments can be supplied with built in digitisers, acquisition modules and a range of storage and communications options.

Model range

3T – Standard seismometer – Datasheet
3TD – Digital seismometer – Datasheet
3TDE – Digital seismometer with acquisition module
3T Portable – Compact seismometer for rapid deployment – Datasheet
3TB – Borehole seismometer – Datasheet

Key features / Benefits

• Force feedback broadband instrument
• Lifting handle and all connectors on the top of the instrument.
• Waterproof and durable with O-ring seals throughout
• Quick and easy, one-person installation
• Digital output and communication versions available

Typical applications

• Nuclear test ban monitoring
• Monitoring seismic activity
• Measuring the response of the ground to shaking
• Global and regional seismic networks
• Noise surveys
• CO₂ storage monitoring
• Tsunami warning
• Earthquake early warning

Example customers

• National Geophysical Research Institute, GS Canada
• Incorporated Research Institutions for Seismology (IRIS) Program for Array Seismic Studies of the Continental Lithosphere (PASSCAL)
• Kandilli Observatory Turkey and ERD

Specifications

SYSTEM

Configuration / Topology: Triaxial orthogonal
Feedback: Force feedback.

PERFORMANCE

Response: 120s – 50Hz standard(Other options available)
Output sensitivity / Clip Level: 2 x 750 V/ms^-1 (1500 V/ms^-1) (Other options available)
Peak / Full scale output: ±10 V differential
Cross axis rejection: Cross-axis rejection of over 65dB; sensor axes orthogonal to within ±0.05°
Linearity: > 107dB horizontal, > 111dB vertical
Lowest spurious resonance: > 140Hz (vertical)
Self-noise: Measured Self noise below the NLNM from >200s to 20Hz (Vertical)
Dynamic range: > 140dB over the entire passband

CALIBRATION

Type: Pulse, sine wave and broadband
Calibration controls: Independent signal & enable lines exposed on sensor connector

MASS / MASS MONITORING

Locking: Remote or automatic electronic mass locking, unlocking and centring
Mass position output band: DC – 120 seconds
Mass recentring range: ±2.5 ° from horizontal

POWER

Power consumption: 0.744W
Power supply: 10 – 36V DC
Optional low power sensor: 5V DC supply (output ±4.5 V)
Protection: TBC
Current at 12VDC: TBC

ENVIRONMENTAL

Operating temperature: -20 to +75ﾰC (-55°C option)
Operating Temperature sensitivity: <0.8 V per 1°C (<0.8 V per 50°C option)
Storage Temperature: TBC
Instrument Levelling: Integrated bubble level and adjustable feet to compensate for up to 5° of tilt.
Case integrity: IP67 for outdoor use and immersion resistance
Shock: TBC
Humidity: TBC
Auto recovery time: TBC
Alignment: North pointers on lifting handle and instrument base

CONTROL

Mass control / locking: Lock, unlock, centre
Offset zeroing: TBC

PHYSICAL

Dimensions: Ø168mm x 344mm
Enclosure: Stainless steel case.
Weight: TBC
Handling: Fixed Lifting handle or swivel eyebolt
Communication / Connectors: Mil-spec connector (optional 1500 psi waterproof connector or user connector)

ACCESSORIES

Handheld Control Unit