Seismic Wave Travel Path velocity models, needed to locate earthquakes. Site Effects site amplification of ground motion by sediments or topography. Regional Earthquake Catalogue activity rate, the proportion of small to large events, maximum credible magnitudes for particular structures or areas. The response of a structure is found by comparing motion on the structure and at its foundation with nearby bedrock motion. Structure response is highly frequency-dependent.
Horizontal motion is more important than vertical.
Translational ground motion can induce torsion in an asymmetric structure. When seismic monitoring is used for emergency response purposes, all parties involved should understand what is possible and what is not. Although earthquake prediction is highly unreliable, other useful information can be provided, both before and after an earthquake. Misunderstandings can be avoided by careful definition of terms. The following terms apply to hazards in general, including fire, flood, cyclones, and earthquakes.