Abstract:

Earthquake hazards comprise any natural phenomenon associated with
earthquakes. Earthquakes are known as the shaking of the Earth’s surface,
producing significant impacts on both physical and urban environments with
severe socioeconomic aspects. Most of the earthquakes are generated at the
boundaries of the lithospheric plates, which float over the mantle’s asthenosphere, converging or diverging. Friction caused by the plates interaction builds up stresses that, when released, produce ground faulting that radiates through the lithosphere producing complex seismic waves, which, in turn, can affect the near built environment.

Although earthquakes mainly control the morphology of the Earth’s surface,
they would unlikely be considered of major significance in the absence of their
effects on the anthropogenic environment, primary and secondary. Primary
earthquake hazards at a site regard the ground shaking due to the passage of the
seismic waves (dynamic deformation) and/or the ground displacements (static
deformation) in the vicinity of the causative fault. Secondary earthquake hazards
are the after-earthquake effects caused by the primary ones and may often be
more catastrophic. Such hazards are ground failures, fire, landslides, rock and
snow avalanches, liquefaction, flooding, tsunamis and seiche that have been
frequently reported to follow the occurrence of strong earthquakes. The measure
of earthquake hazards at a site mainly depends on the size and type of the seismic rupture, its distance from the site and the geological structure between the source and the site’s surface that may impact the seismic energy.

Given that earthquake prediction is still infeasible, the major task in seismological
research is the understanding of earthquake phenomena and their consequences on 

the natural and anthropogenic environment, with the purpose of mitigating them
by providing valid and timely information, to be used for effective earthquake
planning and decision-making processes. Primary and secondary effects are
related with vulnerability, which is defined as a set of prevailing or consequential
physical and sociopolitical conditions that affect a community’s ability to mitigate,
prepare for, or respond to an earthquake hazard (ADCP, 2003). Earthquake
hazards, structural vulnerabilities and exposed values, when combined, yield a
region’s exposure to seismic risk.

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