Measuring Earthquake Magnitude and Intensity

Earthquake magnitude and earthquake intensity measure two fundamentally different things, a distinction that is often blurred in casual usage but is fundamental to seismology. Magnitude is a single number describing the total energy released at an earthquake's source, independent of where it is felt, while intensity describes the strength of shaking and the resulting damage at a specific location, which can vary enormously across a single earthquake depending on distance from the epicenter, local soil conditions, and building construction. A single earthquake therefore has only one magnitude but many different intensity values, one for each place affected.