If a structure (a building, road, etc.)
When an earthquake causes the ground to shake, the base of the seismograph shakes too, but the hanging weight does not.

The results are known as uniform-hazard ground motion Instead the spring or string that it is hanging from absorbs all the movement. The difference in position between the shaking part of the … But in this case, there were plenty of cracks in the ground directly related to fault movement, Valkaniotis said. These displacements are used by seismologists to understand the earthquake source in detail. From these hazard curves, the ground motion amplitudes for a user-specified mean annual frequency can be interpolated and then mapped.
is built across a fault, the ground displacement during an earthquake could seriously damage or rip apart that structure. An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves.Earthquakes can range in size from those that are so weak that they cannot be felt to those violent enough to propel objects and people into the air, and wreak destruction across entire cities. Measureable permanent ground displacements are produced by shallow earthquakes of magnitude 5 and greater. Javascript must be enabled to view our earthquake maps. To access USGS earthquake information without using javascript, use our Magnitude 2.5+ Earthquakes, Past Day ATOM Feed or o Chapter 3: Earthquake Ground Motion 3-3 Each hazard curve provides mean annual frequencies of exceeding various user- specified ground motions amplitudes. The second main earthquake hazard is ground displacement (ground movement) along a fault.