I hate to say this, but it just needs to be pointed out: New Zealand is a very seismically active place, both for earthquakes and volcanoes. 6.3 Richter is a big quake, but far from a colossal one.
I live in a similar seismic hotbed, and we haven't had a really big shake in nearly half-a-century. We're due. I'm concerned.
200 miles north of us, back in 2002, there was a 6.7 Richter shake that we felt where I live. That occurred in a very sparsely populated area with little infrastructure. Three weeks later, there was a 7.9 Richter shake centered just a few miles eastward. We REALLY felt that one here, but were far enough away that no significant damage resulted. That 7.9 tremor was the most powerful quake in the world that year.
The Sumatra 2004 quake that produce the calamitous Indian Ocean tsunami is rated at something in excess of Richter 9.0. The Richter scale measures physical energy release, and is logarithmic. A 9.0 quake is ten times more powerful than an 8.0 quake, a hundred times more powerful than a 7.0. You just had a 6.3.
Yes, that's all very true. However, a 6.3 km earthquake only 5 kms beneath the surface can do just as much (or more) damage as a 7.3 or even an 8.3 centered a lot deeper. And an earthquake located just outside a city will be a lot more damaging than one that strikes a sparsely populated area.
The earthquake Christchurch had back in September was of a similar magnitude (7.1) as the one in Haiti (7.0), but nowhere near as damaging (property or lifewise) as Haiti's thanks to better infrastructure and the fact it struck while most were asleep. It was also situated 40 kms outside of the city, whereas this one is centered right in Lyttelton, one of Christchurch's suburbs, and happened during the day. There has already been a lot more significant damage from this quake than the last.
Interestingly, prior to September's earthquake, the faultline in question wasn't even known. The last big quake to hit the Canterbury area was back in 1888, and wasn't near Christchurch. All the major known faultlines run along the opposite coast and through northern Canterbury, well above Christchurch city.
Anyway, regardless of the cold facts of the matter, people in the city have lost loved ones, or are anxiously awaiting news of loved ones trapped. On top of that, many who were just beginning to get back on their feet after the last earthquake have been hit badly again.
Really, the size on the Richter scale of the quake is irrelevant. What the people of Christchurch are suffering through, on the other hand, is much more relevant.
