Features: High Performance Broadband Seismometer Low Self-Noise Over a Wide Bandwidth Portable Design Low Power Consumption Force-Balance Electric Feedback Robust Mass Locking Mechanism Easy Installation Applications: Local and Regional Broadband Surface or Posthole Installation GSN Installation

The 151-120 Broadband Seismometer is a force-balance feedback sensor with frequency bandwidth 0.0083 Hz (120 sec) -50Hz flat to velocity. The 151-120 contains three independent sensors (one vertical and two horizontal) with built-in electronic feedback circuit, control and power conversion circuits, featuring low noise, large dynamic range and easy installation and use.

The 151-120 has a built-in leveling and mass lock/unlock facilities. The leveling mechanism includes two bubble levels, three adjustable feet and three locknuts which are located on the seismometer's chassis (see photo below).

The 151-120 has built-in mass zero-position adjusting mechanism to perform automatic mass adjustment. As soon as the seismometer is powered it checks the zero position of each component's mass and automatically adjusts the zero position if needed. Monitoring and adjustment of the mass can also be performed via the 130 family High Resolution Recorders using Sensor Control Board, RT527-B01.

The 151-120 is a low noise seismometer (see below Power Spectral Density plot). The leveling mechanism includes two bubble levels, three adjustable feet and three locknuts which are located on the seismometer's chassis (see PDF of 151-120 brochure above).