The measurement of surface gravity

Area of Science:

• Geophysics
• Earth Sciences
• Geodesy

Background:

• Ground-based gravimetry is crucial for monitoring time-variable geopotential changes.
• Modern instrumentation and data processing enhance the observation of surface and land-based gravity variations.

Purpose of the Study:

• To review the basic theory, techniques, and modern instrumentation for ground-based gravimetry.
• To explore diverse applications of gravimetry in observing geophysical phenomena.
• To highlight advancements in gravimeter performance and data interpretation.

Main Methods:

• Detailed examination of absolute, superconducting, and spring gravimeter models (e.g., FG5, OSG, CG5).
• Analysis of data processing and interpretation strategies for geopotential change observations.
• Review of measurement techniques for various geophysical applications.

Main Results:

• Identified large signals (hundreds of µGal) like tides and volcanic eruptions are detectable by all gravimeters.
• Subtle signals (0.1-5.0 µGal) require combining different gravimeter types and strategies.
• Recent advancements show dramatic improvements in gravimeter precision, drift, data recording, and ruggedness.

Conclusions:

• Gravimetry is a sophisticated tool for detecting subtle geophysical signals with improved performance.
• Careful selection of instrumentation and measurement strategies is key to characterizing diverse signals.
• Modern gravimetry routinely contributes to understanding coseismic displacements, post-glacial rebound, hydrology, and sea level changes.