Chapter 2. System Overview

Thank-you for purchasing a Güralp Radian digital seismometer system.

This section describes the key components of a full Radian system. The Radian instrument is the main standard product in the system; other components and accessories can be purchased optionally. Please check your order confirmation to see which components were purchased by your organisation.

2.1 Key features

• A slim-line, 55 mm diameter sonde with 750 mm length for rapid post-hole deployment.

• Bluetooth communication via Android App (available for mobile phone and tablet) confirms integrity of the installation without physical disturbance of site.

• State-of-the-art seismic sensor allows full operation over a full tilt range of ±180° by automatically centring the masses;.

• Streaming and storage of instrument response and calibration parameters dramatically simplifies data management (RESP and Dataless SEED formats).

• Instrument orientation and inclination are measured using an internal magnetometer and MEMS accelerometer to store and stream geographically-aligned waveforms.

• Internal MEMS accelerometer extends the head-room (clip level) of the instrument to 4 g, to capture high-amplitude ground motion from local seismic events.

• Triaxial orthogonal (ZNE) instrument with high cross-axis rejection ratio (> 65 dB).

• Velocity and Acceleration responses available - selected at time of order.

• Retractable, three-jaw, motorised hole-locks for optimal coupling to bore-hole casings.

• Frequency response flat to either velocity or acceleration between 120 s and 200 Hz.

• Low-latency outputs available (approx. 0.01 s data packets).

• Robust and water-proof, encased in SAE 316 corrosion-resistant stainless steel to protect the instrument in extreme environments.

• Accurate time-base provided by either surface GNSS, Precision Time Protocol (PTP), Network Timing Protocol (NTP), or internal clock (< 1 ms drift per day without GNSS).

• No mass locking required; automatic mass centring.

• Dual-redundant microSD card data storage.

• Low power consumption (2.1 W): suitable for temporary deployments using batteries and solar panels.

2.2 Main benefits

2.2.1 Post-hole installations

• Faster deployment reduces total field-work costs and/or allows greater station density for high-resolution seismic monitoring.

• Reduced transportation costs compared to traditional instrumentation.

• Can be drilled/cored into bed-rock for exceptional coupling and noise performance.

• Reduced material costs and footprint compared to traditional seismic vault installations.

• High performance in areas of high cultural noise.

• Dramatically improved noise performance (20 dB reduction compared to vault installations - horizontal components; IRIS figures).

2.2.2 Bore-hole installations

• Deep installations allow you to get closer to the source and farther from cultural noise, for better subsurface characterisation

• Ultra-low noise performance at depth

• Excellent coupling with bore-hole casing provided by three-jaw hole-locks

2.3 Typical applications

2.3.1 Post-hole deployments

• Rapid deployment for volcanic unrest monitoring: recording of long-period tremor events and volcanic-tectonic earthquakes using a single instrument.

• Ultra-dense recording arrays for microseismic monitoring in noisy environments.

• Legislative compliance: Suitable for use in "traffic-light" systems for energy extraction or storage.

• Accurate recordings of strong ground shaking caused by local events.

• Fast installation for rapid-response aftershock deployments.

• Permanent regional and global seismic networks.

• Recording of ice-quakes in glaciers.

2.3.2 Bore-hole deployments

• Passive microseismic monitoring.

• Vertical seismic profiling (VSP).

• Monitoring of moderate-strong teleseismic earthquakes.

• Complement dense surface arrays.