Wānaka Sun       

What will trigger the next Alpine Fault earthquake?

Posted at 6:00am Thursday 13 Feb, 2020 | By Francesca Maria Nespolo journalist@thewanakasun.co.nz

“New Zealand does lie on part of the Ring of Fire, which refers to the belt of volcanic and earthquake activity associated with major plate boundaries circumscribing the Pacific Ocean,” explained John Townend, Director in EQC Programme in Seismology and Fault Mechanics at Victoria University of Wellington. Running about 600km up the spine of the South Island, the Alpine Fault is the boundary of the Pacific and Australian tectonic plates.

Townend denied the possibility of that geographical conspiracy theory where an eruption occurring in Hawaii or Japan might cause a disaster in New Zealand; “Hawaii does not lie on the Ring of Fire (it's right in the middle of the Pacific Plate), and there is no connection between volcanism there or in Japan and earthquakes on the Alpine Fault other than that all three areas are geologically active”.

The Alpine fault is considered to be "late" for a big rupture, which tended to occur every 300 years. The last one was about 1717AD. Most of the data used in a study was collected by sensors that have been constantly recording since 2008. They have picked up about 7700 earthquakes, of which 845 were selected for closer analysis. The Alpine fault has an estimated 30 percent probability of rupturing in the next 50 years, and this rupture will produce one of the biggest earthquakes since European settlement of New Zealand.

Dr Caroline Orchiston at the University of Otago, who is an expert in the hazard posed by earthquakes in New Zealand and how best to prepare for and mitigate their effects, led a major study of the hazard posed by the Alpine Fault ("AF8") and works closely with South Island Civil Defence authorities and other government agencies working to address these issues. Townend encourages to be prepared in case of facing a disaster, due to high chances that an earthquake might occur sooner or later; “there are ways to prepare for future earthquakes (but not to predict them), at personal, community, and national scales. Hopefully you and your colleagues and friends have taken measures yourselves to prepare for earthquakes! See https://getthru.govt.nz/earthquake for helpful advice”.



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