Maxwelton GeoSolutions provides subsurface analyses and visualization through geophysics. Microgravity is the specialty service that is offered and is unique compared to many other firms. The gravity method of exploration detects variations in the densities of subsurface materials. It is non-invasive and is often considered to be more reliable than other methods since it is actually measuring something that actually exists, rather than something produced by the technique.

For years, gravity surveys have been cumbersome and time-consuming to conduct, due to many factors that require corrections: tide, elevation, terrain, latitude and longitude, and others. Gravimeters used to be very simple and all corrections had to be solved “by hand.” Technology has finally caught up with this method, and now gravimeters, when combined with the proper software and operator, can perform all the corrections quickly, and can produce more reliable results in a much more timely fashion. Gravimeters have also become much more sensitive through the years and are able to detect features and bodies that are much smaller and potentially deeper than in previous years, thus the term microgravity. A typical gravity survey can now be done in an amount of time similar to or faster than that of electrical resistivity and other geophysical methods, and usually requires less manpower.

A microgravity survey can be extremely useful in a number of geologic settings. Karst landforms introduce a number of scenarios where there can be problems. Most of the problems are going to be related to the fact that karst landforms are regions where there is a great deal of void space beneath the surface, allowing other substances to travel through these void spaces. Water is not always the only thing that does fill these voids. Some can be air-filled voids that are much closer to the surface than expected. Some can be filled with clay or sediment, while others can be avenues for pollutants to travel. A microgravity survey can detect these voids, and through proper modeling, provide insight as to what maybe occupying the voids.

The gravity method was originally developed for exploration. It has been widely used for subsurface exploration for natural gas and oil. But it can also be applied to any other substance that provides a density contrast from the rock or substance surrounding it. This means that minerals, ores, and other economically important substances can be detected with some geologic knowledge of the region where the survey is conducted. Bedrock can be mapped, and lithologic changes and geologic structures can often be identified through proper modeling of gravity data.

Microgravity can also be a useful tool in mine safety. There is constant concern in the mining industry as to the accuracy of some of the older mine maps. A microgravity survey can be conducted in a permitted region that has some mine map data. A map can be made of the subsurface without even entering it, and can then be compared to an available mine map or can be correlated with other maps to provide valuable insight as to the existence of voids (air-filled or water-filled). This method costs considerably less than drilling, is faster than drilling, and can give a more complete picture rather than just a single snap-shot at particular locations.