Which term describes the magnitude of an earthquake estimated from the amplitude of body waves?

The term that describes the magnitude of an earthquake estimated from the amplitude of body waves is Body-Wave Magnitude, often denoted as M_b. This measurement specifically focuses on the seismic energy released during an earthquake and is calculated using the amplitude of body waves, which travel through the Earth's interior. Body waves include P-waves and S-waves, and they are crucial for assessing the earthquake's size, especially for events occurring at great depths or distances.

The use of body wave measurements allows for more accurate representations of the earthquake's magnitude than other methods, particularly in regions with varying geological conditions. It provides insights into the earthquake’s magnitude independent of surface effects and allows seismologists to better compare earthquakes that occur across different regions and depths.

Other terms like Moment Magnitude refer to a different method of calculating earthquake size that considers the seismic moment, while the Richter Scale and Surface-Wave Magnitude are based on surface waves and their amplitudes, which can be influenced by local geological conditions and may not always yield consistent results for deeper earthquakes. Thus, Body-Wave Magnitude is the most suitable term for estimating earthquake magnitudes based on the amplitude of body waves.