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