What instrument is used to measure the peak ground acceleration during an earthquake?

The instrument used to measure the peak ground acceleration during an earthquake is an accelerometer. An accelerometer is specifically designed to detect and measure the acceleration of ground motion, which includes the immediate effects of seismic activity. It provides critical information about how rapidly the ground accelerates during an earthquake, which is vital for understanding the intensity and potential impact of the seismic event.

Seismometers, while also used in earthquake measurement, are generally designed to detect and record ground motion in terms of velocity and displacement rather than acceleration. This makes them valuable for broader seismic analysis but not specifically tailored for peak ground acceleration measurement. Other instruments, such as strain gauges, measure deformation or strain in materials, and magnetometers are used for detecting magnetic fields, neither of which are suitable for measuring ground acceleration during seismic events.