BOREHOLE AND SUB-SURFACE INSTRUMENTS

Borehole installations offer excellent performance for low-noise detection of weak seismic signals such as from local microseismic events or from regional/teleseismic earthquakes.

We offer a range of options to assist you in achieving measurement at depth, allowing you to get closer to the seismic event and improve the accuracy of sub-surface velocities and event depths.

Our ‘very broadband’ borehole (VBB) system can house a weak-motion seismometer, a strong motion accelerometer, or a combination of the two.

If the borehole deviates from the vertical path we recommend our Radian system which can be installed at any angle.

Our Very Broadband Borehole Systems brochure introduces you to the Güralp borehole systems that are available and the considerations that will help you to select the most appropriate system for your project.
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If you are considering procuring a borehole instrument we also recommend you review our borehole questionnaire early on in your planning as it will help you understand the key information that we require in order to design an effective borehole system.

Through experience, we have learnt that there is a high level of complexity in designing and installing borehole systems. For this reason, we strongly recommend that one of our field engineers manages the installation, particularly for a first deployment.

Radian Posthole and Borehole

High performance sub-surface broadband seismometer with maximum versatility and operational at any angle

The Güralp Radian is a triaxial, force-feedback, broadband, digital seismometer designed for posthole and borehole deployments.

The ultra-wide frequency response between 120 s and 200 Hz makes the Radian ideal for seismic monitoring at all scales, particularly in areas of high cultural noise. For increased flexibility, the high-pass frequency corner can be remotely configured to suit the deployment environment.

At just 55 mm diameter the Radian is the ideal sub-surface digital seismometer and, depending on your intended application, the Radian can be built with either an acceleration or a velocity response.

A velocity response increases long-period gain for monitoring long-period, weak ground motion.

An acceleration response increases gain with frequency for applications such as microseismic monitoring or detection of induced seismicity.

The Radian’s active feedback sensor ensures consistent amplitude and phase response across the bandwidth of the instrument.

The Radian system includes a surface interface unit that delivers advanced data-processing capability and software communications. Data is saved locally in industry standard miniSEED format and streamed remotely using a number of standard protocols - such as SEEDlink, GDI-link and GCF.

Integrated network connectivity allows the surface interface unit to be controlled remotely using our free Güralp Discovery software, or via a standard web browser.

The Radian Posthole is operational at any angle, meaning it can be deployed in uncased holes up to 100 m deep.

The pilot cone at the end of the Radian Posthole is designed to aid direct burial.

  • 120 s to 200 Hz
  • Active feedback sensor for consistent amplitude & phase response up to 200 Hz
  • Velocity or acceleration response available (select at time of ordering)
  • Internal 24-bit digitiser
  • STA/LTA triggering
  • Stainless steel enclosure
  • Remote mass centring
  • Windows, Linux and macOS compatible
  • Internal MEMS accelerometer and magnetometer
  • Select from GNSS (GPS, GLONASS or BeiDou) or PTP (Precision Time Protocol) timing sources
  • Bluetooth (Android and iOS) App for installation integrity checking
  • Data output in multiple file format options
  • IP68 – Protection against effects of permanent immersion under pressure to 2000 m depth (deployment at depths of over 100 m requires optical cable)

The Radian Bore-hole is designed for installations in cased bore-holes of between 60 mm and 100 mm diameter, up to depths of 2000 m.

The instrument has the same modules as the Radian Post-hole, but instead of a pilot cone, it has two three-jaw hole-lock systems, one at each end of the instrument.

The Radian’s hole-lock system is designed to maintain a positive pressure on the bore-hole casing over a prolonged period of time and to fix the instrument in place whilst avoiding the transmission of any stresses. 120 s to 200 Hz

  • 120 s to 200 Hz
  • Active feedback sensor for consistent amplitude & phase response up to 200 Hz
  • Velocity or acceleration response available (select at time of ordering)
  • Internal 24-bit digitiser
  • STA/LTA triggering
  • Stainless steel enclosure
  • Remote mass centring
  • Windows, Linux and macOS compatible
  • Internal MEMS accelerometer and magnetometer
  • Select from GNSS (GPS, GLONASS or BeiDou) or PTP (Precision Time Protocol) timing sources
  • Bluetooth (Android and iOS) App for installation integrity checking
  • Data output in multiple file format options
  • IP68 – Protection against effects of permanent immersion under pressure to 2000 m depth (deployment at depths of over 100 m requires optical cable)



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Discovery is our software platform for the Radian surface interface unit. It dramatically simplifies instrument and data management with a suite of powerful tools operated via a web interface. Find out more:

Applications

  Posthole deployments:

  • Rapid deployment for aftershocks and volcanic unrest monitoring
  • Microseismic monitoring in noisy environments
  • Legislative compliance monitoring for energy extraction or storage
  • Accurate recordings of strong ground shaking caused by local events
  • Permanent regional and global seismic networks
  • Recording of ice-quakes in glaciers

  Borehole deployments:

  • Passive microseismic monitoring
  • Vertical seismic profiling (VSP)
  • Monitoring of moderate-strong teleseismic earthquakes
  • Complement dense surface arrays

3T Borehole

The 3T borehole system designed for borehole diameters of 99 to 203 mm

The 3T Borehole (3TB) offers reliable, high quality performance in long period monitoring applications.
  • Covers the complete seismic spectrum with a single transfer function
  • 120 s to 50 Hz or 360 s to 50 Hz, other bespoke options available on request
  • Hybrid velocity-acceleration responses available offering unrivalled dynamic range
  • Single-jaw hole lock for inner borehole diameters of 99 to 203 mm, or backfill with sand to minimise convection
  • Waterproof and durable with O-ring seals throughout
  • Built-in inclinometer option for attitude checking at depth
  • Operates with a tilt tolerance of up to 2.5 º with an option to increase this to 12.5 º
  • Strain relief mechanism fully isolates the sensors from any motions in the load-bearing cable

Applications

  • Vertical seismic profiling
  • Microseismic monitoring
  • Robust velocity subsurface modelling
  • Teleseismic earthquake monitoring
  • Nuclear test ban treaty monitoring

5T Borehole

The 5TB houses an accelerometer that is designed for strong-motion borehole studies. in cased holes with diameters of 99 to 203 mm

The 5T Borehole (5TB) accelerometer is designed for capturing strong motion and high intensity shaking.
  • Flat acceleration output from DC to 100 Hz (200 Hz option)
  • In addition to the borehole instrument with single jaw hole-lock, there is a 76 mm diameter option suitable for posthole installation with sand backfill to minimise convection
  • Waterproof and durable with O-ring seals throughout
  • Dual output (high and low gain) and optional high/low pass filters
  • Optional electronic compass module to determine downhole attitude
  • Remote DC offset zeroing
  • Strain relief mechanism fully isolates the sensors from any motions in the load-bearing cable

Applications

  • Vertical arrays
  • Earthquake Early Warning systems
  • Strong motion seismic hazard modelling
  • Studies of ground amplification / attenuation

3T/5T Borehole

Achieve exceptional dynamic range with this hybrid 3T/5T borehole package.

The 3T/5T Borehole (3T/5TB) seismometer offers exceptional dynamic range achieved with this dual sensor 3T/5T instrument, designed specifically for borehole applications.
  • Total realised dynamic range of over 200 dB with exceptionally low noise floor
  • Single-jaw hole lock for inner borehole diameters of 99 to 203 mm, or backfill with sand to minimise convection
  • Operates with a tilt tolerance of up to 2.5 º with an option to increase this to 12.5 º
  • Waterproof and durable with O-ring seals throughout
  • Built-in inclinometer option for attitude checking at depth
  • Hole-lock units with cable pass-through available, allowing installation in boreholes already containing an instrument
  • Strain relief mechanism fully isolates the sensors from any motions in the load-bearing cable

Applications

  • Vertical arrays
  • Earthquake Early Warning systems
  • Strong motion monitoring and modelling

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Güralp Systems Ltd.
3 Midas House, Calleva Park
Aldermaston, Reading
RG7 8EA
United Kingdom

Tel: +44 1189 819056
Email: sales@guralp.com
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