anche il GeoNet ipotizza una faglia di thrust in quella zona con la medesima (o circa) direzione della mia. Quello che non fa il GeoNet è dare una spiegazione di tipo Tettonico. Ma questo esula dal suo compito almeno per il momento.
Stanno aumentando i dati sugli aftershock che delineano il piano di faglia:
ma la spiegazione (onestamente) non viene tentata:
A GNS Science image shows the fautline from the September earthquake running through the Canterbury countryside.
The Greendale fault, which caused the September 4 Darfield quake, was unknown to earthquake geologists. Officially, GNS Science won't even name the new fault which ruptured in the Port Hills because it has no surface expression. Some experts, including Canterbury University geologist Mark Quigley, say Christchurch could be vulnerable to further unknown faults and extensive and expensive seismic mapping should take place before rebuilding is contemplated.
Others say while data-gathering should inform long-term planning, it need not delay work to get Christchurch back on its feet. Better seismic data will help longer-term decision making about building design, building codes, standards of infrastructure construction and the location of future development.
GNS Science natural hazards manager Kelvin Berryman says wide-ranging studies need to be commissioned, including mapping to identify other potential faults. Historical patterns will help to gauge the likelihood of future events. He says it's also important to understand the reasons for building failures.
"[But] we can move on without knowing everything that needs to be known."
Berryman says aftershock patterns ease concerns that there could be another large aftershock in the gap between the two faults.
"It's all crystal ball-gazing but the aftershock activity tends to make us think that a lot of the energy has been released in there. It tends to make us think that there is not a big through-going structure that's still waiting to produce a really big earthquake."
