NZ landslides more dangerous than quakes
By Will Harvie
Landslides are significantly more dangerous than earthquakes, according to an analysis by GNS Science. It had identified 1800 fatalities over the past 160 years caused by landslides or slips, which is significantly more than earthquake casualties over the same period, said Jo Horrocks, the Earthquake Commission's chief resilience and research officer.
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The cost of landslides and slips often get rolled into damage caused by storms or floods.
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“Gravity always wins,” warns a 2006 Te Ara Encyclopaedia of NZ article on landslides. “Compared to many other countries, New Zealand has a high number of landslides.”
Mountain ranges are still being uplifted and feature steep slopes. Rock is weakened by folding and faulting. Elsewhere, much of the land is hill country formed by rivers cutting into soft and clay rock. The soils are weak because they are derived from volcanic ash or loess. Throw in high rainfall and earthquakes and the risks increase.
To address these dangers, a National Landslide Database is being created to “capture all current and future landslide information from local and regional councils, Crown entities and geotechnical consultants”.
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