New Zealand's 7.8M Earthquake Really Messed Up The Environment


Robin Andrews

Science & Policy Writer

One of the scars generated by the 7.8 quake. Dr Kate Pedley, University of Canterbury

New Zealand was rocked by a powerful and peculiar earthquake this month, registering as a 7.8M. Occurring at the boundary between two different types of tectonic boundary, scientists are still unsure what type of earthquake it was, what caused it, and whether it was one or two closely spaced quakes.

Either way, the damage to the region was extensive and dramatic – in one striking example, the seafloor off the eastern coast was found to have risen by as much as 2 meters (6.6 feet). Now, as reported by the New Zealand Herald, scientists have managed to photograph some of the fresh fractures that were caused by this incredibly powerful earthquake.


Looking around Kaikoura – a highly damaged town near the epicenter – Dr Kate Pedley, a geologist at the University of Canterbury found a 3-kilometer-wide (1.86 miles) zone full of ruptures, rock falls, slumps, collapses, and crevasses. It’s safe to say that any hypothetical city situated in the countryside near Kaikoura would have been damaged fairly significantly by the 7.8M quake.


Dr Ursula Cochran, a geoscientist working at GNS Science, has also written a blog post related to the quake. She speaks of the Kekerengu Fault, the fastest slipping fault within 100 kilometers (62 miles) from the capital city Wellington, and attached to a key subduction zone wherein part of the Pacific Plate is destructive sliding beneath the Indo-Australian Plate.

Geologists had calculated that three major earthquakes had taken place on this fault line within the last 1,250 years, and that a powerful tremor would be expected once every 300 to 400 years.

“Then, two weeks ago, as if to say, ‘Don’t underestimate me!’ the fault ruptured right through those same trenches,” Cochran writes.


“When the Kekerengu Fault moved as part of the 7.8M Kaikoura earthquake the impacts on the landscape were dramatic,” she adds, noting that “one side of the fault has moved as much as 11 meters [36 feet] with respect to the other side.”

Although the Kekerengu Fault slipping wasn’t the cause of the 7.8M earthquake, the mainshock on November 13 was powerful enough to cause this particular fault to rupture. In fact, it was one of seven others that simultaneously activated when the primary fault slipped. To date, it is still unclear as to which particular fault is the triggering one.


New Zealand continues to be rocked by aftershocks of magnitudes up to 4.5M. As of November 29, there have been 6,580 of them.

Although it’s unlikely there will be another 7.8M quake or greater in the next few years in the same place, some experts have suggested that there is as much of a 32 percent chance of a 7.0M aftershock taking place within the next couple of weeks.


[H/T: New Zealand Herald]


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