The emerging field of gravitational-wave astronomy has provided us with a wealth of new information about our universe. In the near future, the sensitivity of terrestrial gravitational-wave detectors will become limited by the effects of Newtonian noise (gravity gradient noise). A novel sensor for measuring fluctuations in local gravity has been constructed at the ANU. This sensor is designed to measure the influence of Newtonian noise, and could be used to help develop future noise cancellation schemes for gravitational-wave detectors. These cancellation schemes require an accurate characterisation of Newtonian noise, which is yet to be measured. In this seminar I will discuss the development of this sensor and present recent measurements and progress. This instrument is versatile and has other applications outside of the world of gravitational waves. The feasibility of using this sensor to detect gravitational forces produced by earthquakes will also be discussed in this seminar. Since gravitational information travels at the speed of light, these signals will arrive at a remote location significantly faster than any seismic waves. Detection of these signals would allow our sensor to operate as part of an early warning system for imminent seismic waves from earthquakes.