Property

Seismic

 

Information on Earthquakes

Geonet’s Latest earthquake in New Zealand.

GNS Science is a Crown Research Institute whose purpose is “to understand natural Earth system processes and resources, and to translate these into economic, environmental and social benefits”.

  • Stuff’s gallery of ‘before and after’ photos of Christchurch buildings.

Seismic Assessment Process

Prioritisation

In 2011 all parish buildings were prioritised for investigation according to their known risk factors:

  • Age
  • Site
  • Quake risk
  • Use
  • Building materials

Buildings classified as Priority 1, 2, 3, 4, all churches, and any buildings with a heritage status were then prioritised for assessment by an Initial Evaluation Procedure (IEP).  Some buildings were assessed directly by Detailed Assessment (DA).

Initial Evaluation Procedure

For each building, a team from Clendon Burns & Park:

  • Review local council information about the building and site
  • Review geotechnical information about the site
  • Review information gained from a site visit to take measurements, and confirm the building materials and design against council records

CBP then prepare a report using procedures developed by the New Zealand Society of Earthquake Engineering (NZSEE).

The result is a percentage estimate of how each building compares to the New Building Standard (%NBS).

  • A building between 34% and 66%NBS is classified as “Earthquake Risk”
  • A building below 33%NBS is classified as “Potentially Earthquake Prone”.

For buildings that have been estimated as being below 67%NBS, the Working Group may recommend a Detailed Assessment to confirm a rating and give an indication of how the building’s structure might be improved to an acceptable standard.

Detailed Assessment

Consulting engineers would complete a very detailed, possibly intrusive investigation of the building and its site to understand how it would respond in the event of an earthquake.

The result is a determination of the percentage of how each building compares to the New Building Standard (%NBS).

  • A building between 34% and 66%NBS is then determined to be an “Earthquake Risk”
  • A building below 33%NBS is then determined to be “Earthquake Prone”.

 

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