Experts Find Positives For NZ After Big Quake

NEWS RELEASE from NZ Society of Earthquake Engineering

9 September 2007

Experts Find Positives For NZ After Big Quake In Peru

Earthquake experts who have returned from studying the after-effects of last month’s big quake in Peru found a number of positives for New Zealand, and some puzzles as well.

The six-person New Zealand Society of Earthquake Engineering team, who were sponsored by the Earthquake Commission, spent a week inspecting the damage from the magnitude 8 quake that occurred 150km south of Lima on 15 August.

The quake resulted in more than 500 deaths and extensive damage to many thousands of buildings and structures.

Team leader David Hopkins said Lima, the capital city of 8 million people, was not seriously affected, but the towns of Pisco, Ica, Chincha and Paracas suffered extensive damage and major disruption.

An unusual feature of the earthquake was the extended duration of shaking; buildings were rocked for two minutes.

In the worst-affected areas, ground-shaking was comparable to what could be expected in a major earthquake along the eastern part of the North Island. This provided the team with an indication of likely performance of buildings and infrastructure in New Zealand.

Relevant points for New Zealand noted by the team included:

- The good performance of buildings that were well designed and well built
- Good performance of water towers, bridges and grandstands
- The importance of communications immediately following an event
- The importance of response planning – the four R’s: Reduction, Readiness, Response and Recovery.

- The wisdom of special protection for hospitals, such as the base isolation used recently in Wanganui and Wellington. Ica Regional Hospital was extensively damaged and put out of commission.
- The value in having a comprehensive network of instruments to measure the strength of ground shaking and building response
- The need to plan the co-ordination of international response and aid
- The survival with minimal disruption of industrial facilities, including a steel mill, did much to mitigate economic effects
- The need to better understand the mechanics of earthquake shocks and their propagation outwards from the source
- The value of an effective building controls regime.

“A puzzling feature of the earthquake was the good performance of unreinforced masonry (brick) buildings,” Dr Hopkins said.

“ The variation of the effects on similar buildings in the same area was extreme. Some buildings showed no signs of having been through two minutes of strong shaking.”

“This could be taken to mean that masonry buildings will perform better than we think, or that the soil characteristics affected the nature of the shaking. Unfortunately, there is little information available to solve the puzzle.”

Dr Hopkins said the performance of buildings was of particular interest in the context of recent New Zealand legislation on earthquake-prone buildings. This enables territorial authorities to require quake-prone buildings be strengthened or demolished.

NZSEE President, Professor Michael Pender of Auckland University, said the team hoped New Zealand agencies would consider providing technical support to Peru.

“In 2001, the Ministry of Foreign Affairs and Trade supported the rebuilding of a hospital in Bhuj in India, following its total loss in an earthquake,” he said.

“Peruvian agencies visited by the team indicated interest in New Zealand’s base isolation technology, New Zealand-made seismic instruments, and in our building controls regime.”

The technical reconnaissance mission was conducted by the NZSEE, supported from its own funds and with generous support from the Earthquake Commission and the Department of Building and Housing. Other contributing organisations were GNS Science, Greater Wellington, Transit NZ, and Connell Wagner.

NZSEE and EQC have a long record of sending information-gathering teams to countries where large earthquakes have occurred.

ENDS

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