Quote: The faults that have been rupturing in the recent Christchurch earthquakes are very old faults that have been reactivated.

I’m intrigued by this statement. What were the 1869 Christchurch Earthquake and the 1870 “Lake Ellesmere” Earthquake but not reactivation of these same or very similar fault lines. Possibly slightly smaller events, but from the same essential locations.

Surely stating any other case as above is but a splitting of hairs.

When is this issue to be addressed by the various professions, for up to now there seems to be a consistent effort to almost deny the very existence of these historical earthquakes.

http://www.geonet.org.nz/earthquake/historic-earthquakes/top-nz/quake-13.html

June 5 1869, “Christchurch” earthquake1
Since 1853, when organised European settlement of Christchurch and Lyttelton began, ten or so earthquakes are known to have shaken Christchurch city strongly enough to cause chimney and minor building damage and/or significant contents damage (i.e. caused shaking intensities of MM 6 or more). Among these are large earthquakes, centred some distance from Christchurch.
Only one earthquake is known to have caused pervasive building and chimney damage throughout the CBD and nearby suburbs, encompassing Avonside, Linwood, Fendalton and Papanui. This event was the 1869 June 5 8:00 am (local time).
The highest intensity of shaking was clearly confined to within a few kilometres of Christchurch CBD. Contents damage occurred in many shops and homes, and many chimneys and chimney tops fell or were cracked. The stone spire of St John’s church in Latimer Square was cracked from top to bottom, reportedly the worst damage in the city. In the Government buildings, the tops of two chimneys came down, plaster was cracked, and several stones displaced. Similar damage occurred in some other brick and stone buildings, including Matson’s building, the NZ Loan & Trust building and the NZ Insurance building. Avonside and more generally, the area north of the Avon River and east of and along Papanui Road, were most affected with many chimneys damaged or down. The side of one brick house collapsed in Manchester Street. The relatively low level of masonry damage in the city is consistent with MM 7 rather than the MM 7 Р8 assigned by Dibble et al. (1980).
Outside the city intensities rapidly decreased, reaching MM 5 at Kaiapoi and Halswell. However, a few chimneys and household contents were damaged at Lyttelton.
The short duration of shaking, small spatial extent of MM 7, the occurrence of aftershocks and the rapid attenuation are consistent with an earthquake at very shallow depth within a few kilometres of the CBD.
August 31 1870, “Lake Ellesmere” earthquake1
The 1870 earthquake, on August 31 at 6:53 pm (local time) was more widely felt than the 1869 earthquake, with the highest intensities around Christchurch, at locations on Banks Peninsula and South Canterbury, but felt at least as far south as Dunedin, on the West Coast and North Canterbury.
In Christchurch city, there was damage to household and shop contents as well as isolated chimney damage, e.g. one or two chimneys fell in Avonside, one in Chester Street and another in Papanui Road. The upper parts of several chimneys were rotated near the railway station. There was also isolated minor structural damage. At St John’s church in Latimer Square the stone cross fell, causing damage to several roof slates, and some old cracks opened in the stonework. Old cracks in the Town Hall also moved. The damage is consistent with MM 6 at most. Several chimneys, as well as household goods, were damaged at Lyttelton, about Banks Peninsula and in South Canterbury as far south as Timaru, the intensity not exceeding MM 6, except possibly at Temuka, and the eastern side of Lyttelton Harbour.
The spatial distribution of intensities indicates an earthquake at greater depth than the 1869 earthquake. This is consistent with the reported longer duration of strong shaking, the occurrence of only one or two slight aftershocks and observations of the two shocks separated by a short interval that are almost certainly P and S waves.
1extracts courtesy of Downes & Yetton (in prep.)

I have being a little concerned about the risk of a offshore quake. If you look at the aftershocks you’ll note that they tend to (by large) stop at the beach, it’s almost like they have hit a ‘wall’. It will be great to get some data on it!