Urban seismic risk



Urban seismic risk is the risk of earthquakes damaging or destroying people and things in towns and cities. Even if a big earthquake is likely urban seismic risk can be minimized with good earthquake construction, and seismic analysis. One of the best ways to deal with the issue is through an earthquake scenario analysis. Earthquake engineering can reduce the risk.

International projects
The IDNDR secretariat launched the RADIUS (risk assessment tools for diagnosis of urban areas against seismic disasters) initiative in 1996 to promote worldwide activities for the reduction of urban seismic risk, which experienced rapid growth particularly in developing countries, by helping to raise public awareness.

Urban risk and planning
One of the disaster risk reduction themes set forth by the United Nations International Strategy for Disaster Reduction project PreventionWeb, is urban risk and planning. This theme refers to the measurement and management of urban hazards and vulnerability in order to improve awareness and local capacity to effectively reduce disaster risk.

Toronto


Cities are a mixture of old and new construction as in this picture. Note the old brick building mixed in with the new highrises, and the famous Toronto CN Tower. Similar to methodologies used in nuclear reactors, a seismic walkdown of the city is the best way to identify vulnerabilities and possible places for improvement.

Toronto is located on the shores of Lake Ontario, the site of much microseismicity. Toronto was struck by a 5.0 magnitude earthquake on June 23, 2010, and a 5.1 magnitude earthquake on May 17, 2013.

There are many places where the risk of seismic damage to older buildings is quite high. Old brick buildings on poor soils are highly vulnerable to earthquake damage, particularly when the mortar holding the bricks together has decayed. Problems increase if there is the possibility for soil or soil liquefaction.

Even in buildings which are capable of withstanding an earthquake without structural failure there may be risk to people due to interior hazards. Items such as suspended ceilings and light fixtures have almost no seismic ruggedness. Warehouse stores where heavy merchandise is stacked are a particular hazard.