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Scene of destruction caused by earthquake, 16 Nov. 1901 : a 2.5ft deep fissure on the road between Cheviot and Port Robinson. |
One article even suggests that the moon caused the quake. Others report ministerial visits. The similarity with the Kaikoura Earthquake is uncanny.
However, it is of concern that the Cheviot earthquake led to the almost total abandonment of that rural town. While the Christchurch Star would not have reported each and every aftershock, it does report many for almost a year after the initial 6.9 earthquake. The last report I found was in September - 10 months later - and this reports 6 severe aftershocks in quick succession. It seems that the main reason damage to buildings in Cheviot reduced was because settlers stopped using cob and brick - instead using corrugated iron and wood - even for chimneys. Light buildings are more robust in a sharp earthquake.
From what I've learned about earthquakes, the best predictor of earthquake behaviour today, is to know how the same geological system behaved when it last moved. There are patterns to earthquakes. If Cheviot is anything to go by, Kaikoura and environs will be subject to severe aftershocks for about a year.
2 comments:
Nice work Joel – digging out the Cheviot event. There may be more historical information around this event that could be useful to assessing when the next major event occurs in the upper South Island – another 50 years or ???? I recall a DSIR report published in 1976 that caused a flutter at Parliament where I was then working. The DSIR assessed that the next ‘big’ Pacific-Australasian continental plate movement of global scale affecting NZ could occur in the upper South Island, affecting areas to the north (Wellington) and south (Canterbury and Southern Alps). Most of those scientists have probably move on, but the question I would want to ask them (and today’s geo-scientists familiar with NZ seismic history) is whether this latest event was in fact that ‘big’ plate movement earlier data seemed to forecast, or was it an indicator that the ‘big’ plate adjustment they forecast is still to come?
GeoNet and GNS don't show the 1901 Cheviot shake on its map of NZ's largest earthquakes, despite it being rated: severe, located shallow at 12 kms depth, and of magnitude 6.8. Located between Cheviot and Kaikoura it was powerful enough to knock the top off Christchurch Cathedral. The map also doesn't show the severe 1922 Motunau earthquake (depth 20 kms, magnitude 6.4) which also damaged the Cathedral. The impression given by the map is that the 2010 and 2011 Christchurch quakes, and the Kaikoura quake were a surprise. San Andreas fault experts mostly argue that the best predictor of a future earthquake is past events. NZ's public can be better informed and warned by its institutions.
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