<
https://theconversation.com/clues-left-by-the-alpine-faults-last-big-quake-reveal-its-direction-this-will-help-nz-prepare-for-the-inevitable-next-rupture-240879>
"One of the world’s most anticipated earthquakes is the next major surface
rupture of the Alpine Fault in the South Island of New Zealand.
With a 75% chance of it happening within the next 50 years, there is justified
interest in the likely magnitude, extent and intensity of ground shaking and
impacts on the landscape, infrastructure and buildings.
A key – and so far unanswered – question is which direction the fault rupture
will take.
Our new research reveals for the first time that the Alpine Fault ruptured from
south to north in the great magnitude 8+ earthquake of 1717.
We developed our technique to determine rupture direction based on the
Kekerengu Fault after the 2016 Kaikōura earthquake. But our method is globally
applicable for use in realistic earthquake scenarios and thus can contribute to
better societal preparedness.
In an Alpine Fault earthquake, there’s no direction that’s good news for the
West Coast of the South Island. But a north-to-south rupture would send excess
seismic energy into the relatively unpopulated region of Fiordland and the
Tasman Sea.
A south-to-north rupture on the other hand is forecast to cause higher
intensity shaking in the populated regions of Canterbury, Marlborough, Tasman
and the northern West Coast.
In the Kaikōura earthquake, Wellingtonians experienced this influence of
rupture direction on shaking intensity. The south-to-north rupture meant more
seismic energy was focused towards the capital city than, for example,
Christchurch.
So, while rupture direction has been observed to make a big difference in
modern earthquakes, it is not something geologists have been able to directly
determine for past earthquakes."
Cheers,
*** Xanni ***
--
mailto:xanni@xanadu.net Andrew Pam
http://xanadu.com.au/ Chief Scientist, Xanadu
https://glasswings.com.au/ Partner, Glass Wings
https://sericyb.com.au/ Manager, Serious Cybernetics
