Which instrument measures the magnitude of an earthquake?

1. An earthquake is a sudden vibration of the Earth's surface, caused by movement of molten material or rock within the crust. 2. The magnitude of that vibration is measured on the Richter scale. 3. The other three instruments all record atmospheric conditions instead. 4. A hygrometer measures humidity and a thermometer measures temperature. 5. A wind vane shows wind direction and a barometer measures atmospheric pressure, so none of them concerns the Earth's crust. _Source: NECTA CSEE 2023 Geography 013, Question 1: Multiple Choice Questions, item (v)_