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PAGER FAQs - 17 Found
The ground motion intensities are calculated using the USGS ShakeMap system. A ShakeMap is a representation of ground shaking produced by an earthquake; it is a combination of observed and estimated shaking values. ShakeMaps are better constrained when numerous seismic stations (triangles) or macroseismic values (circles) provide intensity observations. Global ShakeMaps (GSM) are primarily predictive, so the ground shaking intensities are inherently uncertain. The ground shaking intensity at sites throughout the region depends on the earthquake's magnitude, the geometry, size, and depth of the ruptured fault, the distance from the earthquake fault, the rock and soil conditions at sites, and variations in the propagation of seismic waves from the earthquake due to complexities in the structure of the Earth's crust.