Seismic Shake Map and Intensity of Quake

Geographic representation of seismic Ground shaking is Shake Map. Intensity is one of the ways that ground shaking is expressed, along with more quantitative measures like velocity and acceleration. The information Shake Map presents is different from the earthquake magnitude. Magnitude is the number that represents the energy released in an earthquake; a single number representing magnitude is assigned to each earthquake. Intensity, on the other hand, is a measure of how the ground shook at a particular site. So, while an earthquake has one magnitude and one epicenter, it produces a range of ground shaking levels at sites throughout the region.

M 9.0 - HONSHU MEGA THRUST

These different intensities depend on distance from the earthquake, the rock and soil conditions at geographical sites, and variations in the propagation of seismic waves from the earthquake due to complexities in the structure of the Earth's crust. Shake Map focuses on the ground shaking produced by the earthquake, rather than the characteristics of the earthquake source.