And the answer: earthquakes.
The Richter scale measures the strength of earthquakes, and was developed by Charles Richter in a 1935 paper. Initially called the "magnitude scale," the Richter scale uses seismograph data to evaluate an earthquake's intensity. It's sometimes called the Richter magnitude scale or the Gutenberg–Richter scale.
With the introduction of the Richter scale in 1935, humankind had discovered a way to finally and concretely measure earthquakes—an often disastrous phenomenon that has persisted on Earth since the very unstable beginning of our planet. However, although Richter’s scale offered a new tool for understanding magnitude in earthquakes—AKA the amount of energy released by an earthquake—scientists soon began to discover that new measurements were required to understand particular earthquakes, and that Richter’s invention was limited by applicable frequencies and distance ranges. Thus, in order to take advantage of the growing number of globally distributed seismograph stations, an extension of Richter’s original magnitude scales were developed. These scales looked to better measure body wave magnitude (Mb) and surface wave magnitude (Ms). Together, the system came together to become what’s known as the Moment Magnitude scale, which is most widely used today.
Aside from magnitude, earthquakes have a physical impact and often leave behind a wake of destruction. This effect is called intensity, and is measured with the Modified Mercalli scale. The original Mercalli scale dates back to 1902, well before the idea of the seismograph had come along, but got a reboot in 1931 and is still in use today. Rather than seeking to quantify the damage, the Modified Mercalli scale uses an observation-based approach and focuses more on an earthquake’s visible effects.
Learn more about the history of measuring earthquakes here.