How often does your job take you beyond your comfort zone. How often do you stand in the ski hut at the bottom of the hill putting on your boots and imagine swooshing down the infamous Kamikaze $\blacklozenge$ run. And then when you get there and look over the edge you say to yourself “What was I thinking, I must be out of my mind to do this”.
My previous post that began this series of articles on surveys introduced the idea of solving the gravity response of a sphere mathematically and how this is well within the capability of detecting geologic anomalies below the surface with instruments. In this article we will take a deeper look into how we can reason about the physical phenomenon of a gravity response and using this to model simple geometric objects.
Geophysics has to do with physics of the earth. There are academic reasons for studying the shape and behavior of the earth, as well as commercial ones. The US Geological Survey USGS, and the Geological Survey of Canada GSC, as well as mapping agencies related to both of them are involved in geophysical surveys. A lot of data is available from these agencies for use by the public. We shall see later how to obtain gravity network control points and GPS survey control points from the GSC. Similar data is available in many other countries.
