# Geophysics an Introduction

“The pounding in my head is compounded exponentially by each bounce of the truck. The drive between stations is only 20 km but it might as well be 100. Once we arrive to our site we find a local farmer who is able to help us find a spot to bury the sensors that will record electromagnetic data from the earths crust for the next 36 hours. Lucky for us we have a native Setswana speaker. It takes 2.5 hours to set up the next station, and most of that time is spent digging in the ground to bury the sensors. On our return to the lodge, we upload the data for later analysis, ready the truck for tomorrow, recharge the batteries on the equipment, and finally, relax to the sight of a fantastic African sunset.”

Geophysics applies the laws of physics to the dynamics of the earth through the study of the seismic waves, gravity, heat flows, magnetism, and electro-conductivity. The earth is made up of the crust, mantle and core. While studying the rocks on the surface of the earth tells us much about the crust, it reveals very little about the remaining 99% of the planet. Drilling has reached at most, a depth of about 12 km (7 miles) which barely taps the maximum 50 km (30 miles) depth of the core. The much hotter mantle is at an additional depth of 2900 km (1,740 miles) and the core thickness is 7,000 km (4,200 miles) in diameter.

The field of geophysics allows the scientists to interpret the inner workings of our planet by applying the laws of physics to the outer crust. The collection and analysis of field data requires the use of computers and complex mathematical formulas. The data is used to produce maps in a detailed image that allows the geophysicist to extrapolate the location of petroleum traps located far below the surface of the earth.

Studies in geology and physics are required to become a geophysicist. Geophysicists are commonly mathematicians, physicists, and computer specialists. They often work in the field of oil and gas exploration. Where a geologist studies the earth in a single location for long periods of time, the geophysicist may be called upon to travel to remote locations to study the earth in flux for a much shorter time.

We have barely punched the surface of our planet. Since we currently have no way to reach the deeper layers, we must gather what information we can from its surface and use that to draw conclusions about what may lie below. In that realm of science, the geophysicist is our expert.