The machine used to measure the intensity of earthquakes is called a seismometer or seismograph. This instrument detects and records the vibrations caused by seismic waves as they travel through the Earth during an earthquake. Seismometers come in various types, including analog and digital, and consist of a mass suspended from a spring to detect ground motion. When an earthquake occurs, the relative movement between the mass and the ground generates a trace on a recording medium, allowing scientists to analyze the quake's magnitude, duration, and location. Such data are crucial for understanding seismic activity and assessing earthquake risks.