A Nineteen Day Earth Tide Measurement with a MEMS Gravimeter

Abstract

The measurement of tiny variations in local gravity enables the observation of subterranean features. Gravimeters have historically been extremely expensive instruments, but usable gravity measurements have recently been conducted using MEMS (microelectromechanical systems) sensors. Such sensors are cheap to produce, since they rely on the same fabrication techniques used to produce mobile phone accelerometers. A significant challenge in the development of MEMS gravimeters is maintaining stability over long time periods, which is essential for long term monitoring applications. A standard way to demonstrate gravimeter stability and sensitivity is to measure the periodic elastic distortion of the Earth due to tidal forces -the Earth tides. Here we present a nineteen day measurement of the Earth tides, with a correlation coefficient to the theoretical signal of 0.979. The estimated bias instability of the proposed gravimeter is 8.18 µGal for