This 4-Ton Steel Ball Causes Artificial Earthquakes to Help Us Understand the Earth's Crust

An old seismological station in Germany holds the history of the modern geophyics field.
Jessica Miley

If you have ever wanted to experience an earthquake without the danger, then you need to get to Hainberg, near Göttingen, Germany. Hidden away there is an old seismological station full of fascinating instruments and experiments related to the field of geophysics. 

The Wiechert Earthquake Station was built in 1902 by the German physicist and geophysicist, Emil Wiechert. Wiechert used the station as a place to carry out experiments that would become foundation knowledge in the field of geophysics. 

This 4-Ton Steel Ball Causes Artificial Earthquakes to Help Us Understand the Earth's Crust
Source: Instituto Física of the Universidade Federal do Rio de Janeiro/Wikimedia Commons

His experiments included building seismographs to record tremors. Several of these instruments have been recording data uninterruptedly since then, making them the world’s oldest, still functioning seismographs. 

Wiechert was fascinated by learning about what was under the surface of the earth. He hypothesized that the Earth’s interior was a series of shells and in 1896, he published the first verifiable model of this theory. 

He explained that because the density of the rocks found on the Earth’s surface is different to the mean density of the Earth, then it was clear that the earth was made up of layers of rocks with different densities. 


He also argued that the Earth has a heavy iron core. Weichert invited many leading scientists in the field of geophysics to join him at the station. One of particular note was the German physicist named Ludger Mintrop.

Mintrop was a dedicated student of Wiechert, he would also go on to be known as one of the founding figures of modern geophysics. He is most famous for his 1908 invention that can artificially produce earthquakes. 

The collected data can then be used to determine the geological structure underneath the surface. His invention consists of a 14-meter tall steel scaffolding rig, from which a 4-ton steel ball was dropped into the bedrock of shell limestone below. Portable seismographs on site were then used to measure the seismic reactions of the ball dropping at various distances away from the fall site. 

This 4-Ton Steel Ball Causes Artificial Earthquakes to Help Us Understand the Earth's Crust
Source: Stefan Flöper/Wikimedia Commons

The experiment was a big success as it allowed Mintrop the means to develop a three-dimensional image of the immediate area below the surface of the earth. Mintrop proved by creating these small artificial earthquakes it was possible to begin to understand the distinct boundaries between rock layers beneath the surface including the difference in solid and liquid layers. 

The data also allowed him to make a hypothesis about the exact nature of geological structures near the surface. Mintrop developed this technology and used it to form the geological exploration company Seismos GmbH. The company explored tappable deposits of minerals and rock by using seismic waves. 

The iron ball was later replaced by dynamite. This method of geological exploration is still used today by large oil companies to search for deposits of crude oil, natural gas, and other minerals. Mintrop’s original experiment site is still present at Hainberg, albeit with a few modern upgrades. 

The ball is now raised up with an electric motor and has a remote release mechanism. But visitors to the seismic research center can still watch the experiment be carried out.

Via: AtlasObscura

message circleSHOW COMMENT (1)chevron