Measuring and reporting amplitudes and periods



The following instructions were adopted by the Commission on Practice of the International Association of Seismology and Physics of the Earth's interior (IASPEI) at Canberra, in December. They should be used whenever possible in reporting amplitudes and periods.

The determination of earthquake magnitude is based on observations of amplitude A and period T of seismic waves. It is essential for subsequent earthquake studies to report the time that an observation of A and T is made.