In September 2010, a Richter 7.1. earthquake ripped through Christchurch, New Zealand, causing considerable building damage but fortunately only injuring two people. Earthquakes aren't news in New Zealand - in fact, the country's strong building codes probably saved many lives in this incident alone. What was new was the cause - which some analysts at the time thought was a new and previously unknown fault line.
New Zealand lies on the so-called Ring of Fire, the horse-shoed zone around the Asian, Australasian, and American Pacific coasts along which volcanoes and earthquakes are unusually common. New Zealand alone has more than ten thousand earthquakes each year, although at most a few hundred can be felt without the aid of a seismometer, and only a few of those will be strong enough to be genuinely dangerous to human life or property. The country has long been careful about building codes, so fortunately - as in this case - fatalities are minimal. The most serious earthquake in the country's history happened in 1931 at Hawke's Bay, when 256 people died.
The Christchurch earthquake of 2010, also known as the Canterbury earthquake, occurred at about 4:30 a.m. on September 4, early enough in the morning that most people were at home in bed (another factor which is believed to have saved many lives). The earthquake lasted about forty seconds and originated at an epicenter just 25 miles from Christchurch. Christchurch has a population of nearly 400,000, so obviously the damage and loss could have been far worse. As it was, billions of dollars of property damage have occurred, much of which will be paid by the Earthquake Commission.
One of the most intriguing outcomes for analysts was the discovery that, in the words of one Canterbury University geologist, a "new fault" had been opened up. The quake shifted the Earth by eleven feet along the line - in comparison to the most serious earthquake last year, which pushed New Zealand about one foot closer to Australia than it had been before. The most active zone in New Zealand is the Alpine Fault Line, which stretches through South Island. Geologists were unsure initially whether the new fault line reflected new activity on the Greendale fault or the Alpine fault, or whether it might have implications for the Wellington fault line in North Island. The latest TV New Zealand reports indicated that the country's Institute of Geological and Nuclear Sciences (commonly known as GNS Science) believed a new fault line was indeed the culprit.