Terra-Scope: a MEMS-based vertical seismic array

Steven D. Glaser; Min Chen; Tom E Oberheim

doi:10.1117/12.605242

17 May 2005 Terra-Scope: a MEMS-based vertical seismic array

Steven D. Glaser, Min Chen, Tom E Oberheim

Proceedings Volume 5765, Smart Structures and Materials 2005: Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems; (2005) https://doi.org/10.1117/12.605242
Event: SPIE Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring, 2005, San Diego, California, United States

Abstract

The Terra-Scope system is an affordable 4-D down-hole seismic monitoring system based on independent, microprocessor-controlled sensor Pods. The pods are nominally 50 mm in diameter, and about 120 mm long. They are expected to cost approximately $6000 each. An internal 16-bit, extremely low power MCU controls all aspects of instrumentation, eight programmable gain amplifiers, and local signal storage. Each pod measures 3-D acceleration, tilt, azimuth, temperature, and other parametric variables such as pore water pressure and pH. The following parameters are independently controllable at each pod: pre-trigger length, post-trigger length, trigger time stamp, sampling rate, trigger level, trigger parameters, non-volatile storage, and calibration and self-evaluation. Each Pod communicates over a standard digital bus (e.g. RS-485) through a complete web-based GUI interface, and has a power consumption of less than 400mW. Three-dimensional acceleration is measured by pure digital force-balance MEMS-based accelerometers. These accelerometers have a dynamic range of more than 115 dB and a frequency response from DC to 1000 Hz. The accelerometer chip uses a 5th order delta-sigma feedback loop to yield a noise floor of less than 30 ngrms/√Hz. Accelerations above 0.2 g are measured by a second set of MEMS-based accelerometers, giving a full 160 dB dynamic range. The prototype of the device is currently undergoing evaluation. The first array will be installed in the fall of 2005.

Citation Download Citation

Steven D. Glaser, Min Chen, and Tom E Oberheim "Terra-Scope: a MEMS-based vertical seismic array", Proc. SPIE 5765, Smart Structures and Materials 2005: Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems, (17 May 2005); https://doi.org/10.1117/12.605242

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