Our deepest sympathies go out to everyone in Christchurch. Many of our staff here have families and whanau down there – we’re thinking of you all, and hoping for good news.
I’ve been in touch with our expert Dr Hamish Campbell at GNS. Although he’s at the thick of things, he did dash off this email to me about the geological movement:
“This magnitude 6.3 shallow earthquake (only 5 km), considered to be an aftershoock of the 7.1 Darfield Earthquake, relates to movement on a reverse (thrust) fault. This is another previously unrecognised and hence unnamed fault.
It is very different in character to the Darfield Earthquake which related to E – W transcurrent movement on a vertical plane. This event relates to thrust movement from E to W. So, the east side is trying to climb up over the west side, enabling crustal shortening.
This is classic plate collision tectonics.
The fault is almost certainly oriented NE-SW, in keeping with the general trend of most active faults in NZ, associated with plate collision. “
We’ll keep you posted with updates as they come to hand. GNS’s own GEONET site is one of the best sources of information.