Sensitivity, Accuracy and Limits of the Lightweight Three-Component SmartSolo Geophone Sensor (5 Hz) for Seismological Applications

Martin Zeckra , Koen Van Noten, Thomas Lecocq 

The use of Nodal systems based on autonomous geophone-based instruments entered the field of Seismology only recently. These lightweight solutions revolutionized seismological fieldwork through lightweight and wholistic instruments that are faster to deploy and easier to handle. The IGU-16HR series of SmartSolo® is one example, but yet lacking a thorough lab-based performance analysis. Here, we fill the knowledge gap, by performing a series of lab and field-based tests that focus on the sensors performance. The investigated parameters are the instruments transfer function, self-noise and overall performance to classical seismometer-based instruments. In the real-world application we show examples of H/V measurements of ambient vibrations in urban environments and the performance ranges with teleseismic waveform recordings. Under lab conditions, the nodal systems perform equally well as standard seismometers (e.g., Lennartz 3D/5s), even in the frequency range down to 0.2Hz, way below their natural frequency. The restitution can be carried out correctly with manufacturer given transfer function. At least for the vertical component, the instruments self-noise reaches the lower boundary of the global minimum noise level, confirming the ability to properly record teleseismic phases down to 0.1 Hz. In ambient noise studies the instrument limits are already reached at 0.8 Hz, but still resolve the fundamental frequencies within the methods uncertainty ranges, based on classical instrument data. These versatile and easy-to-use nodal systems are useful and reliable for a wide range of seismological applications. In addition, their installation is faster and reduced prices open the doors towards Large N installations and research studies for groups that face limited financial budgets.