Wellington may just have dodged a devastating earthquake.
Scientists estimate that an average of one magnitude-7 quake will strike New Zealand every 10 years and a magnitude 8 once a century. A 7.8 magnitude quake hit Fiordland in July.
If the same quake had struck in a more populated area such as Wellington, its impact could well have resulted in thousands of deaths.
Interestingly, even though instrumental records have been kept in New Zealand only since 1903, Richter ratings have been given to earthquakes prior to that time.
New Zealand has had a "dream run" for the past five decades, with "a remarkably low number of large damaging quakes for a country that has similar earthquake activity to California".
Characteristically it would appear that earthquakes in California are considerably more shallow than in New Zealand (30 cf. 60 Km depth), consequently are considerably more likely to result in damage ... the parallel drawn has to be somewhat specious.
There seems little basis for magnitude 7 and 8 earthquakes being equitably distributed, nor that 'probabilities' deduced from active areas resulting in damage need relate to the local setting .... certainly there is insufficient New Zealand data to deduce a magnitude 8 earthquake will occur here once a century.
Friday, October 16, 2009
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